Variability in the distance from the end of the gray matter to the end of the conus medullaris: a case-triggered histological investigation

Maximilian Scheer Department of Neurosurgery,

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Bruno Griesler Institute of Anatomy and Cell Biology, Medical Faculty, and

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Elisabeth Ottlik Institute of Anatomy and Cell Biology, Medical Faculty, and

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Christian Strauss Department of Neurosurgery,

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Christian Mawrin Department of Neuropathology, University Magdeburg, Germany

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Christian Kunze Department of Radiology, Martin Luther University Halle-Wittenberg, Halle; and

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Julian Prell Department of Neurosurgery,

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Stefan Rampp Department of Neurosurgery,

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Sebastian Simmermacher Department of Neurosurgery,

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Jörg Illert Department of Neurosurgery,

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Heike Kielstein Institute of Anatomy and Cell Biology, Medical Faculty, and

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Christian Scheller Department of Neurosurgery,

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OBJECTIVE

The background for this investigation was the dramatic course of a 14-year-old girl with a spontaneous hemorrhage in the area of the conus medullaris resulting in a complete cross-sectional syndrome with bladder and bowel dysfunction. Despite immediate surgical treatment, the patient showed close to no postoperative improvement. Subsequent histopathological examination of the removed masses revealed a cavernoma. To better understand the link between the site and symptoms of conus medullaris lesions, the authors performed a literature search and then histological examination of the conus medullaris of 18 cadaveric specimens from body donors.

METHODS

After a literature search regarding the histological features of the structure of the conus medullaris did not lead to satisfying results, the authors performed histological examination of the conus medullaris in 18 cadaveric specimens from body donors. The largest (a) and smallest (b) diameters of the conus medullaris were measured, noting individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter were analyzed.

RESULTS

Gray matter displayed in the form of a butterfly figure was found along almost the entire length of the conus medullaris. The specific slide containing the end of the gray matter was noted. The distance between the caudal ending of the gray matter in the conus and the macroscopical end of the conus medullaris was defined as the gray matter to cone termination (GMCT) distance. There were great individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Analysis of the correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter showed no significant sex-specific differences in the GMCT distance. Patient body height and transverse diameter at the end of the gray matter were found to be correlated positively with the GMCT distance. Moreover, greater height also correlated positively with the cross-sectional area at the end of the gray matter.

CONCLUSIONS

This report is, to the authors’ knowledge, the first published description of the histological structure of the conus medullaris and can serve as the basis for a better understanding of neurological deficits in patients with a conus medullaris syndrome. Findings that gray matter can be detected far into the conus medullaris, with large individual differences in the endpoint of the gray matter, are important for operative care of intramedullary masses and vascular malformations in this area. It is therefore important to use electrophysiological monitoring during these operations.

ABBREVIATIONS

GMCT = gray matter to cone termination.

OBJECTIVE

The background for this investigation was the dramatic course of a 14-year-old girl with a spontaneous hemorrhage in the area of the conus medullaris resulting in a complete cross-sectional syndrome with bladder and bowel dysfunction. Despite immediate surgical treatment, the patient showed close to no postoperative improvement. Subsequent histopathological examination of the removed masses revealed a cavernoma. To better understand the link between the site and symptoms of conus medullaris lesions, the authors performed a literature search and then histological examination of the conus medullaris of 18 cadaveric specimens from body donors.

METHODS

After a literature search regarding the histological features of the structure of the conus medullaris did not lead to satisfying results, the authors performed histological examination of the conus medullaris in 18 cadaveric specimens from body donors. The largest (a) and smallest (b) diameters of the conus medullaris were measured, noting individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter were analyzed.

RESULTS

Gray matter displayed in the form of a butterfly figure was found along almost the entire length of the conus medullaris. The specific slide containing the end of the gray matter was noted. The distance between the caudal ending of the gray matter in the conus and the macroscopical end of the conus medullaris was defined as the gray matter to cone termination (GMCT) distance. There were great individual variations in the distance from the caudal ending of the gray matter to the macroscopically visible end of the conus medullaris. Analysis of the correlations of these differences with sex, body height, gray matter transverse diameter, and cross-sectional area at the end of the gray matter showed no significant sex-specific differences in the GMCT distance. Patient body height and transverse diameter at the end of the gray matter were found to be correlated positively with the GMCT distance. Moreover, greater height also correlated positively with the cross-sectional area at the end of the gray matter.

CONCLUSIONS

This report is, to the authors’ knowledge, the first published description of the histological structure of the conus medullaris and can serve as the basis for a better understanding of neurological deficits in patients with a conus medullaris syndrome. Findings that gray matter can be detected far into the conus medullaris, with large individual differences in the endpoint of the gray matter, are important for operative care of intramedullary masses and vascular malformations in this area. It is therefore important to use electrophysiological monitoring during these operations.

In Brief

Because of the unusual course of a spontaneous hemorrhage in the area of the conus medullaris, the authors performed histological examination of the conus medullaris in the case patient and 18 cadaveric specimens and found great individual variation in the distance from the caudal ending of the gray matter to the macroscopic end of the conus medullaris. Awareness of the gray matter to cone termination (GMCT) length and use of electrophysiological monitoring are important for operative care in the area of the conus medullaris.

The dramatic case of a 14-year-old girl who presented with a sudden onset of severe lumboischialgia (sciatica) led us to the present investigation. MRI showed a spontaneous hemorrhage in the area of the conus medullaris resulting in a complete cross-sectional syndrome with bladder and bowel dysfunction along with other deficits appearing within a few hours. Despite immediate care, the patient had close to no postoperative improvement. This dramatic and rather unusual case showed us the necessity for further research of the conus medullaris and surrounding structures.

The spinal cord consists of white and gray matter. The latter comprises the nerve cell bodies. These form a structure shaped like a butterfly that can be seen from the cervical to the lumbar spinal levels.1,2 Histological examination of whether and to what extent this structure continues distally has, to our knowledge, not yet been reported. The conus medullaris is the distal end of the spinal cord,3 and many descriptions of syndromes associated with damage to the cauda equina or the conus medullaris have been reported.4 Symptoms of conus medullaris syndrome include sudden onset of back pain, perianal numbness, symmetric lower-extremity motor weakness with hyperreflexia, and early-onset bowel and bladder dysfunction.3–5 Conus medullaris syndrome may be caused by compression (e.g., disc herniation, fracture, or tumor), infection (e.g., abscess), ischemia, hemorrhage, or inflammation (e.g., transverse myelitis).3,6

A search for information revealed that neither established textbooks of anatomy and neurosurgery nor PubMed provided information regarding the histological structure of the conus medullaris. However, knowledge of the histological structure is the basis of and essential for understanding pathologies and operative care. For neurosurgeons, these findings are relevant to the surgical treatment of intramedullary tumors (such as astrocytoma, ependymoma, and metastases)6 and vascular malformations such as cavernomas and arteriovenous malformations in the area of the conus medullaris.7

We found only two publications reporting investigations of the arterial basket of the conus medullaris and the intradural microanatomy of the sacral nerve roots at their origin from the conus medullaris,8,9 although the level of conus medullaris termination has been reported several times.10–12 In an MRI-based examination, the location of the termination of the conus medullaris varied between T12 and L3, with the highest incidence at the lower end of L1.11 Interestingly, histological examination showing that the filum terminale contains axons and ependymal cells has already been reported.13,14

To investigate the possible connection between the site and symptoms of conus medullaris injuries, we examined the histological structure of the conus medullaris in 18 cadaveric specimens from body donors.

Methods

Case Report

The case of a 14-year-old girl who presented a sudden onset of severe lumboischialgia prompted this investigation. Within a few hours, the patient developed a complete cross-sectional syndrome below the level of T12, with bladder and bowel dysfunction. MRI showed a hemorrhage of 8 × 6 mm in the area of the conus medullaris (Fig. 1A). Immediate surgical treatment was provided via laminectomy at the level of T11. After the opening of the dura, a typical intramedullary cavernoma was found. The posterior spinal artery was identified in the surgical corridor and spared (Fig. 2). After the opening of the arachnoid, CSF with coagulated blood was released, followed by a complete microscopic removal without coagulation. The histological examination confirmed the diagnosis of a cavernoma (Fig. 3). The patient’s neurological status remained unchanged immediately after the intervention. There was a timely transfer to a rehabilitation facility. In the clinical follow-up 12 months postoperatively, the flaccid paralysis with bladder and bowel dysfunction remained, while sensitivity levels were slightly improved. Postoperative MRI did not reveal any suspicious findings of residual cavernoma (Fig. 1B).

FIG. 1.
FIG. 1.

A: Preoperative sagittal T2 turbo spin echo (TSE) MR image showing hemorrhage in the area of the conus medullaris and a full bladder. B: Postoperative sagittal T2 TSE MR image showing complete removal of the cavernoma.

FIG. 2.
FIG. 2.

Photographs of intraoperative findings showing the spinalis posterior above the hemorrhage (upper left) and the cauda equina below the hemorrhage. Figure is available in color online only.

FIG. 3.
FIG. 3.

Histological examination of the cavernoma. A and B: Sections with H&E stain showing blood vessels with thickened walls and irregular shape. C: Old hemorrhages (blue iron stain) are present in the lesion. D: Elastica van Gieson stain demonstrating the irregular structure of blood vessel convolutions. Figure is available in color online only.

Sample Acquisition

Eighteen donated bodies conserved with ethanol (containing 3% formaldehyde) were investigated. Written informed consent for scientific investigations was given by all body donors prior to death at the Institute of Anatomy and Cell Biology of the Martin Luther University Halle-Wittenberg. A laminectomy was performed with a rongeur. To obtain the part of interest of the spinal cord, a transverse dissection was executed at the intervertebral level between T10 and T11 as well as approximately 2 cm below the macroscopic end of the conus medullaris. For each specimen, it was noted on which level the spinal cord ended.

The filum terminale was removed while sparing the conus medullaris. Each sample was distinctly labeled and stored in Falcon tubes. Because of damage dealt to the spinal cords during prior preparation that affected the transverse diameter or the cross-sectional area at the end of the gray matter, 7 samples could not be included in analyses (see the Results section on comparison of the gray matter to cone termination [GMCT] distance and cross-sectional area of the conus medullaris).

Fixation

The samples were stored in a 4% formaldehyde solution for 24 hours. Afterward, the tissue was washed in purified water for 12 hours. Until dehydration, the samples were kept in 70% ethanol.

Dehydration was performed with a Thermo Scientific Citadel 2000 tissue processor. The tissues were placed in cassettes. An ascending alcohol series was performed by embedding in xylene. The samples were then embedded in paraffin with great attention to their cranio-caudal orientation.

Tissue Sectioning and Klüver-Barrera Staining

From the caudal to the cranial end of the conus medullaris, 10-µm-thick slices were taken in 1-mm intervals. Sections were carefully transferred to a water bath (37°C) for straightening. Afterward, sections were mounted on glass slides (Thermo Scientific SuperFrost Plus adhesion slides) and dried overnight at 40°C.

For Klüver-Barrera staining, the slides were deparaffinated. Afterward, the slides were incubated in warm 1% Luxol fast blue solution (60°C overnight). Specimens were rinsed in 96% ethanol and subsequently in purified water. Slides were submerged in 0.05% lithium carbonate solution for 20 seconds. Afterward, they were differentiated in 70% ethanol and rinsed in purified water until the desired staining intensity was obtained. Nucleus staining was performed with Harris’ hematoxylin solution (Sigma-Aldrich). After this, slides were blued under flowing water and specimens were dehydrated afterward. Finally, slides were incubated in xylene, mounted with Eukitt mounting medium (Sigma-Aldrich), and covered with coverslips.

Microscopical Analysis

Stained slides were examined systematically by three independent observers. Starting from the most caudal slice taken from the conus medullaris, specimens were analyzed for the existence of organized gray matter. The specific slide containing the ending point of the gray matter was noted separately by all three observers and later discussed for each sample. With this evidence, the distance between the caudal ending of the gray matter in the conus and the macroscopical end of the conus medullaris could be defined as the gray matter to cone termination (GMCT) distance (Fig. 4).

FIG. 4.
FIG. 4.

Schematic depiction of the GMCT distance.

Based on the agreement of all three observers, the ending point of gray matter was determined and the greatest (a) and smallest (b) diameters of the conus medullaris were measured. With the help of these data, the elliptical area (A) of the cross section of the ending point of gray matter in the conus medullaris was calculated (A = π × 0.5a × 0.5b).

The microscopic images were generated with a NanoZoomer-SQ digital slide scanner (C13140-01; Hamamatsu Photonics). Microscopy was performed with manual review of set focus points and ×40 magnification. Later, the images were viewed with the NDP.view2 viewing software (U12388-01; Hamamatsu Photonics)15 and analyzed with open-source photo imaging software (ImageJ).

Statistical Analysis

Statistical analysis was performed using SigmaPlot 12.0 software. The individual GMCT distances were arithmetically averaged and the standard error of the mean was calculated. Attention was paid to sex-specific differences. We also searched for correlations between GMCT distances and individual body heights of donors, as well as the calculated areas at the level of the ending of the gray matter. These correlations were calculated with the help of Pearson’s correlation coefficient. The strength between the two variables was graded with three different r values. For r ≥ 0.1 the effect was small, if r ≥ 0.3 the effect was moderate, and if r ≥ 0.5 the effect was large.

Results

Samples from 18 body donors (12 female and 6 male, age range 66–93 years, height range 1.50–1.90 m) were examined. The GMCT distance and the diameters at the end of the gray matter as well as the macroscopic end of the medullary cone were determined. The results were categorized by the end of the conus medullaris being in area T12–L1 versus L1–2.

Microscopic pictures were taken, which show the typical butterfly figure of the gray matter until the far distal portion. Figure 5 shows representative pictures at different levels of the conus medullaris. The ratios of gray matter to white matter changed from level to level. Further distally, the gray matter took up more space than the white matter.

FIG. 5.
FIG. 5.

Microscopic images of focal points of the conus medullaris and its termination prepared with a digital slide scanner at ×40 magnification with Klüver-Barrera staining. Gray matter appears as a typical butterfly figure at 5 mm to cone termination (A), 2 mm to cone termination (B), and 1 mm to cone termination (C), whereas no gray matter can be seen at 0 mm to cone termination (D). Figure is available in color online only.

The mean value of the GMCT distance of the donated cadavers was 4 mm (Fig. 6A), and the GMCT distances ranged between 0 and 8 mm (Fig. 6B). The majority of the examined donors showed a macroscopic cone end at level L1–2 (n = 15). Eleven of the 12 women and 4 of the 6 men showed a macroscopic cone end at level L1–2. Only 2 men and 1 woman showed an end at level T12–L1 (n = 3) (Fig. 6C).

FIG. 6.
FIG. 6.

Macroscopic and microscopic properties in examined cadaveric specimens. A: GMCT distance (mean ± SEM, n = 18). B: Interindividual differences in the GMCT distances (n = 18). C: Distribution of the different macroscopic terminations of the cadaveric spinal cords (n = 18). D: Sex-specific GMCT distances (mean ± SEM, 12 females and 6 males).

The GMCT distance was also examined on a sex-specific basis. Mean values of 3.8 mm (women) and 4.5 mm (men) were determined (Fig. 6D). The difference was not found to be significant. A positive correlation between GMCT distance and body height could be shown. With an increasing body height, the GMCT distance also increased slightly (Fig. 7A). However, the effect was small (r = 0.18).

FIG. 7.
FIG. 7.

Analysis of the data from cadaveric specimens. A: Correlation analysis for height of donor bodies and GMCT distance (n = 18). B: Correlation analysis for the area at the end of the gray matter and GMCT distance (n = 11). C: Correlation analysis for body height and area at the end of the gray matter (n = 11). D: Correlation analysis for the transverse diameter of the conus medullaris at the end of the gray matter and GMCT distance (n = 11).

A comparison of the GMCT distance and cross-sectional area of the conus medullaris at the level of the end of the gray matter presented a slightly negative correlation. An r value of −0.11, indicating a small effect, could be detected (Fig. 7B). Seven samples could not be used for this particular investigation due to damage during preparation.

The cross-sectional area of the conus medullaris was also compared with the body height of the donors. Here we found a moderate positive correlation with an r value of 0.33. With increasing body height, the cross-sectional area of the conus medullaris at the end of the gray matter gets larger (Fig. 7C). Here as well, 7 samples could not be used for this investigation due to damage during preparation.

The comparison of GMCT distance and transverse diameter at the end of the gray matter also showed a moderate positive correlation (r = 0.44). This means that with increasing GMCT distance a larger transverse diameter of the conus medullaris at the end of the gray matter could be measured (Fig. 7D). As mentioned above, 7 samples could not be used for this particular investigation due to damage during preparation.

Discussion

Hemorrhages in the area of the conus medullaris caused by a cavernoma are extremely rare as cavernomas are predominantly located intracranially and much less often in an intramedullary location.16 The localization in the area of the conus medullaris is probably the rarest localization.17 Despite the relatively small hemorrhage and immediate surgical treatment, the preoperative cross-sectional syndrome did not improve in the presented patient. This is very unusual as other case reports with acute onset of symptoms and timely surgical treatment report a good recovery.17,18 The primary symptoms in our case were typical for diseases in the area, also known as conus medullaris syndrome.19 Gross-total resection of the cavernoma was achieved and documented on MRI. Thus, the risk of rebleeding events as may occur in subtotal resection was very small.18

In the clinical follow-up 12 months after surgery, the patient’s flaccid paralysis below the level of T12, also known as anterior horn syndrome, remained.20,21 Anterior horn syndrome occurring in a case with a dorsal hemorrhage can possibly be explained by an effect on interneurons, which as part of the pyramidal tract connect the corticospinal tract with alpha motor neurons.2,22,23 In addition to our case, only 2 similar case descriptions of children24,25 and 18 case reports of adults exist.17,18,24,26–30

It is recommended to treat symptomatic findings surgically, because symptoms usually improve or at least do not deteriorate postoperatively.18 Only one case description was published of a patient with an acute paraplegia due to a cavernoma in the area of the conus medullaris. In this case, a complete recovery within 3 months without any surgical procedure was reported.27

In addition to vascular processes, intramedullary spinal cord tumors are also of neurosurgical relevance. About 10% of all intramedullary tumors are located in the conus medullaris.31,32 These central nervous system tumors are rare and extremely challenging for the surgeon.33 Surgeries in the area of the conus medullaris may lead to severe complications, such as bowel and bladder disorder, erection problems, and paresis.34 The use of intraoperative neurophysiological monitoring and intraoperative ultrasound may help to optimize the extent of resection with minimal damage to normal tissue.33,34

The results of our investigation showed that the gray matter extends far distally through the conus medullaris while presenting the familiar butterfly figure of the gray matter in almost the entire length of the conus medullaris. The butterfly figure in the upper part of the conus medullaris was shown in MRI studies.35,36 In the present investigation, the butterfly figure was still visible far distally, whereby the ratio of gray and white substance changed. Going further distally, the gray matter took up more space in relation to the white matter. The distance between the caudal ending of gray matter in the conus and the macroscopical end of the conus medullaris was defined as the GMCT distance. The mean GMCT distance value for all body donors was 4 mm. However, these observations have to be treated with caution, since a more precise examination using more specific stains is not possible in conserved cadaveric donor specimens. A marked variability in the range of GMCT distances (0–8 mm) could be found. Because of these interindividual variations, it is possible to have different neurological deficits due to an identical process. For example, in the presented case, the described hemorrhage might have caused milder symptoms in a different patient.

The termination of the conus medullaris at level L1–2 was also found in other studies11,37 and is in line with our results. Liu et al. showed that in women the termination of the conus medullaris was further distal than in men.11 In our examination, 11 of 12 women showed a macroscopic cone end at this level. However, the number of men (n = 6) was too small to make a valid general observation. A correlation between the termination of the conus medullaris and age in adults was not found.11 Other investigations have already shown that the end of the conus medullaris is further distal in children.10 Sonographic studies have demonstrated the rostral migration of the conus medullaris level in early infancy.12 Thus, the older age of the examined body donors, who therefore had completed spinal ascension, explains our finding of the mean termination of the conus medullaris at the level of T12–L1.

We found sex-specific differences in the GMCT distances, although they were not significant. With a mean value of 4.5 mm, men showed a higher GMCT distance than women, who had a mean value of 3.8 mm. This result could possibly be related to the differences in height between the sexes. Since we were able to examine only 12 female and 6 male body donors, we can merely speculate as to whether sex differences influence the GMCT distance in a relevant matter.

Our results show that the GMCT distance increases with greater body height. A larger GMCT distance did not directly correlate with the cross-sectional area at the end of the gray matter but with the transverse diameter at this level. These observations may be explained by the interindividual rostral migration of the conus medullaris, possibly due to differences in body growth.2,12 Partial damage of the conus medullaris restricted the sample size for analysis of correlations between the cross-sectional area and, respectively, the transverse diameter and the GMCT distance. Thus, the data of the presented study are insufficient to explain these observations conclusively, and it can only be speculated that the differences in migration distance have a multifactorial etiology.

Our study shows that the conus medullaris is a relevant structure in spinal pathologies and that we need larger investigations regarding the possible variations of this entity as well as the origin of those variations. With further studies, a better understanding and ultimately an improvement in the therapy of uncommon cases such as the case presented here could be achieved. The lack of consistency in the GMCT distance underlines the importance of interoperative neurophysiological monitoring. In two different patients, a similarly located spinal lesion could lead to entirely different symptoms. For individualized treatment, intraoperative neurophysiological screening is needed to provide important guidance for surgeons. To get a better overview of the operating area, thin-slice MRI may be useful for visualizing the distribution of white and gray matter within the conus medullaris, a technique that should be further researched and evaluated.

Conclusions

This description of the histological structure of the conus medullaris, which to our knowledge is the first to be reported, can serve as the basis for a better understanding of neurological deficits occurring in patients with conus medullaris syndrome. Gray matter was detected far into the conus medullaris, and we found a great variability in the GMCT distance, from the end of the gray matter to the macroscopic end of the conus medullaris. These findings are important for operative care of intramedullary masses and vascular malformations in this area. The great variability of the GMCT distance suggests that similar lesions at the same location may cause heterogenous symptoms. Therefore, it is important to use electrophysiological monitoring during operation in this region. In the future, a thin-slice MRI scan before surgery may be helpful to plan a surgical approach.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Scheer, Scheller. Acquisition of data: Griesler, Ottlik, Mawrin, Kunze, Rampp. Analysis and interpretation of data: Griesler, Ottlik, Prell. Drafting the article: Scheer. Critically revising the article: Griesler, Ottlik, Strauss, Mawrin, Kunze, Prell, Rampp, Simmermacher, Illert, Kielstein, Scheller. Study supervision: Strauss, Kielstein, Scheller.

References

  • 1

    Lüllmann-Rauch R. Taschenlehrbuch Histologie. 2nd ed. Thieme; 2006.

  • 2

    Trepel M. Neuroanatomie: Struktur und Funktion. 5th ed. Elsevier Urban & Fischer; 2012.

  • 3

    Nene Y, Jilani TN. Neuroanatomy, conus medullaris. In: StatPearls. StatPearls Publishing; 2020. Accessed February 3, 2021. https://www.ncbi.nlm.nih.gov/books/NBK545227/

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Rider IS, Marra EM. Cauda equina and conus medullaris syndromes. In: StatPearls. StatPearls Publishing; 2020. Accessed February 3, 2021. https://www.ncbi.nlm.nih.gov/books/NBK537200/

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Brouwers E, van de Meent H, Curt A, et al. Definitions of traumatic conus medullaris and cauda equina syndrome: a systematic literature review. Spinal Cord. 2017;55(10):886890.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Burton MR, De Jesus O, Mesfin FB. Conus and cauda equina tumors. In: StatPearls. StatPearls Publishing; 2020. Accessed February 3, 2021. https://www.ncbi.nlm.nih.gov/books/NBK441878/

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7

    Boström A, Kanther NC, Grote A, Boström J. Management and outcome in adult intramedullary spinal cord tumours: a 20-year single institution experience. BMC Res Notes. 2014;7:908.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Hauck EF, Wittkowski W, Bothe HW. Intradural microanatomy of the nerve roots S1–S5 at their origin from the conus medullaris. J Neurosurg Spine. 2008;9(2):207212.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Martirosyan NL, Kalani MYS, Lemole GM Jr, et al. Microsurgical anatomy of the arterial basket of the conus medullaris. J Neurosurg Spine. 2015;22(6):672676.

  • 10

    Jung JY, Kim EH, Song IK, et al. The influence of age on positions of the conus medullaris, Tuffier’s line, dural sac, and sacrococcygeal membrane in infants, children, adolescents, and young adults. Paediatr Anaesth. 2016;26(12):11721178.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Liu A, Yang K, Wang D, et al. Level of conus medullaris termination in adult population analyzed by kinetic magnetic resonance imaging. Surg Radiol Anat. 2017;39(7):759765.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Rozzelle CJ, Reed GT, Kirkman JL, et al. Sonographic determination of normal conus medullaris level and ascent in early infancy. Childs Nerv Syst. 2014;30(4):655658.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Kural C, Guresci S, Simsek GG, et al. Histological structure of filum terminale in human fetuses. J Neurosurg Pediatr. 2014;13(4):362367.

  • 14

    Picart T, Barritault M, Simon E, et al. Anatomical and histological analysis of a complex structure too long considered a simple ligament: the filum terminale. World Neurosurg. 2019;129:e464e471.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Deroulers C, Ameisen D, Badoual M, et al. Analyzing huge pathology images with open source software. Diagn Pathol. 2013;8:92.

  • 16

    Awad IA, Polster SP. Cavernous angiomas: deconstructing a neurosurgical disease. J Neurosurg. 2019;131(1):113.

  • 17

    Badhiwala JH, Farrokhyar F, Alhazzani W, et al. Surgical outcomes and natural history of intramedullary spinal cord cavernous malformations: a single-center series and meta-analysis of individual patient data: clinic article. J Neurosurg Spine. 2014;21(4):662676.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Balasubramaniam S, Mahore A. Cavernoma of the conus medullaris mimicking transverse myelitis. Singapore Med J. 2013;54(2):e24e27.

  • 19

    Han IH, Kuh SU, Chin DK, et al. Surgical treatment of primary spinal tumors in the conus medullaris. J Korean Neurosurg Soc. 2008;44(2):7277.

  • 20

    Diaz E, Morales H. Spinal cord anatomy and clinical syndromes. Semin Ultrasound CT MR. 2016;37(5):360371.

  • 21

    Garg N, Park SB, Vucic S, et al. Differentiating lower motor neuron syndromes. J Neurol Neurosurg Psychiatry. 2017;88(6):474483.

  • 22

    Drenckhahn D, ed. Benninghoff - Drenckhahn Taschenbuch Anatomie. Elsevier, Urban & Fischer; 2011.

  • 23

    Gertz SD, Liebman M. Basiswissen Neuroanatomie: Leicht verständlich - Knapp - Klinikbezogen. 4th ed. Georg Thieme; 2003.

  • 24

    Khalatbari MR, Hamidi M, Moharamzad Y. Pediatric intramedullary cavernous malformation of the conus medullaris: case report and review of the literature. Childs Nerv Syst. 2011;27(3):507511.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Odom GL, Woodhall B, Margolis G. Spontaneous hematomyelia and angiomas of the spinal cord. J Neurosurg. 1957;14(2):192202.

  • 26

    Hernández D, Moraleda S, Royo A, et al. Cavernous angioma of the conus medullaris as a cause of paraplegia. Spinal Cord. 1999;37(1):6567.

  • 27

    Kasliwal MK, Naik V, Kale SS, Sharma BS. Conus cavernoma: a rare cause of spontaneously resolving paraplegia. Surg Neurol. 2008;69(1):103104.

  • 28

    Montano N, Signorelli F, Tufo T, et al. Teaching NeuroImages: extralesional bleeding of conus medullaris cavernoma. Neurology. 2010;75(1):e1.

  • 29

    Obermann M, Gizewski ER, Felsberg J, Maschke M. Cavernous malformation with hemorrhage of the conus medullaris and progressive sensory loss. Clin Neuropathol. 2006;25(2):9597.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 30

    Winkler EA, Lu A, Rutledge WC, et al. A mini-open transspinous approach for resection of intramedullary spinal cavernous malformations. J Clin Neurosci. 2018;58:210212.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 31

    Sandalcioglu IE, Gasser T, Asgari S, et al. Functional outcome after surgical treatment of intramedullary spinal cord tumors: experience with 78 patients. Spinal Cord. 2005;43(1):3441.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Shrivastava RK, Epstein FJ, Perin NI, et al. Intramedullary spinal cord tumors in patients older than 50 years of age: management and outcome analysis. J Neurosurg Spine. 2005;2(3):249255.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Juthani RG, Bilsky MH, Vogelbaum MA. Current management and treatment modalities for intramedullary spinal cord tumors. Curr Treat Options Oncol. 2015;16(8):39.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 34

    Taskiran E, Ulu MO, Akcil EF, Hanci M. Intraoperative neuromonitoring in surgery of cauda equina and conus medullaris tumors. Turk Neurosurg. 2019;29(6):909914.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Rossi C, Boss A, Steidle G, et al. Water diffusion anisotropy in white and gray matter of the human spinal cord. J Magn Reson Imaging. 2008;27(3):476482.

  • 36

    Yiannakas MC, Liechti MD, Budtarad N, et al. Gray vs. white matter segmentation of the conus medullaris: reliability and variability in healthy volunteers. J Neuroimaging. 2019;29(3):410417.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 37

    Nasr AY. Clinical relevance of conus medullaris and dural sac termination level with special reference to sacral hiatus apex: anatomical and MRI radiologic study. Anat Sci Int. 2017;92(4):456467.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • Collapse
  • Expand
  • FIG. 1.

    A: Preoperative sagittal T2 turbo spin echo (TSE) MR image showing hemorrhage in the area of the conus medullaris and a full bladder. B: Postoperative sagittal T2 TSE MR image showing complete removal of the cavernoma.

  • FIG. 2.

    Photographs of intraoperative findings showing the spinalis posterior above the hemorrhage (upper left) and the cauda equina below the hemorrhage. Figure is available in color online only.

  • FIG. 3.

    Histological examination of the cavernoma. A and B: Sections with H&E stain showing blood vessels with thickened walls and irregular shape. C: Old hemorrhages (blue iron stain) are present in the lesion. D: Elastica van Gieson stain demonstrating the irregular structure of blood vessel convolutions. Figure is available in color online only.

  • FIG. 4.

    Schematic depiction of the GMCT distance.

  • FIG. 5.

    Microscopic images of focal points of the conus medullaris and its termination prepared with a digital slide scanner at ×40 magnification with Klüver-Barrera staining. Gray matter appears as a typical butterfly figure at 5 mm to cone termination (A), 2 mm to cone termination (B), and 1 mm to cone termination (C), whereas no gray matter can be seen at 0 mm to cone termination (D). Figure is available in color online only.

  • FIG. 6.

    Macroscopic and microscopic properties in examined cadaveric specimens. A: GMCT distance (mean ± SEM, n = 18). B: Interindividual differences in the GMCT distances (n = 18). C: Distribution of the different macroscopic terminations of the cadaveric spinal cords (n = 18). D: Sex-specific GMCT distances (mean ± SEM, 12 females and 6 males).

  • FIG. 7.

    Analysis of the data from cadaveric specimens. A: Correlation analysis for height of donor bodies and GMCT distance (n = 18). B: Correlation analysis for the area at the end of the gray matter and GMCT distance (n = 11). C: Correlation analysis for body height and area at the end of the gray matter (n = 11). D: Correlation analysis for the transverse diameter of the conus medullaris at the end of the gray matter and GMCT distance (n = 11).

  • 1

    Lüllmann-Rauch R. Taschenlehrbuch Histologie. 2nd ed. Thieme; 2006.

  • 2

    Trepel M. Neuroanatomie: Struktur und Funktion. 5th ed. Elsevier Urban & Fischer; 2012.

  • 3

    Nene Y, Jilani TN. Neuroanatomy, conus medullaris. In: StatPearls. StatPearls Publishing; 2020. Accessed February 3, 2021. https://www.ncbi.nlm.nih.gov/books/NBK545227/

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Rider IS, Marra EM. Cauda equina and conus medullaris syndromes. In: StatPearls. StatPearls Publishing; 2020. Accessed February 3, 2021. https://www.ncbi.nlm.nih.gov/books/NBK537200/

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Brouwers E, van de Meent H, Curt A, et al. Definitions of traumatic conus medullaris and cauda equina syndrome: a systematic literature review. Spinal Cord. 2017;55(10):886890.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Burton MR, De Jesus O, Mesfin FB. Conus and cauda equina tumors. In: StatPearls. StatPearls Publishing; 2020. Accessed February 3, 2021. https://www.ncbi.nlm.nih.gov/books/NBK441878/

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7

    Boström A, Kanther NC, Grote A, Boström J. Management and outcome in adult intramedullary spinal cord tumours: a 20-year single institution experience. BMC Res Notes. 2014;7:908.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Hauck EF, Wittkowski W, Bothe HW. Intradural microanatomy of the nerve roots S1–S5 at their origin from the conus medullaris. J Neurosurg Spine. 2008;9(2):207212.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Martirosyan NL, Kalani MYS, Lemole GM Jr, et al. Microsurgical anatomy of the arterial basket of the conus medullaris. J Neurosurg Spine. 2015;22(6):672676.

  • 10

    Jung JY, Kim EH, Song IK, et al. The influence of age on positions of the conus medullaris, Tuffier’s line, dural sac, and sacrococcygeal membrane in infants, children, adolescents, and young adults. Paediatr Anaesth. 2016;26(12):11721178.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Liu A, Yang K, Wang D, et al. Level of conus medullaris termination in adult population analyzed by kinetic magnetic resonance imaging. Surg Radiol Anat. 2017;39(7):759765.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Rozzelle CJ, Reed GT, Kirkman JL, et al. Sonographic determination of normal conus medullaris level and ascent in early infancy. Childs Nerv Syst. 2014;30(4):655658.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Kural C, Guresci S, Simsek GG, et al. Histological structure of filum terminale in human fetuses. J Neurosurg Pediatr. 2014;13(4):362367.

  • 14

    Picart T, Barritault M, Simon E, et al. Anatomical and histological analysis of a complex structure too long considered a simple ligament: the filum terminale. World Neurosurg. 2019;129:e464e471.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Deroulers C, Ameisen D, Badoual M, et al. Analyzing huge pathology images with open source software. Diagn Pathol. 2013;8:92.

  • 16

    Awad IA, Polster SP. Cavernous angiomas: deconstructing a neurosurgical disease. J Neurosurg. 2019;131(1):113.

  • 17

    Badhiwala JH, Farrokhyar F, Alhazzani W, et al. Surgical outcomes and natural history of intramedullary spinal cord cavernous malformations: a single-center series and meta-analysis of individual patient data: clinic article. J Neurosurg Spine. 2014;21(4):662676.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Balasubramaniam S, Mahore A. Cavernoma of the conus medullaris mimicking transverse myelitis. Singapore Med J. 2013;54(2):e24e27.

  • 19

    Han IH, Kuh SU, Chin DK, et al. Surgical treatment of primary spinal tumors in the conus medullaris. J Korean Neurosurg Soc. 2008;44(2):7277.

  • 20

    Diaz E, Morales H. Spinal cord anatomy and clinical syndromes. Semin Ultrasound CT MR. 2016;37(5):360371.

  • 21

    Garg N, Park SB, Vucic S, et al. Differentiating lower motor neuron syndromes. J Neurol Neurosurg Psychiatry. 2017;88(6):474483.

  • 22

    Drenckhahn D, ed. Benninghoff - Drenckhahn Taschenbuch Anatomie. Elsevier, Urban & Fischer; 2011.

  • 23

    Gertz SD, Liebman M. Basiswissen Neuroanatomie: Leicht verständlich - Knapp - Klinikbezogen. 4th ed. Georg Thieme; 2003.

  • 24

    Khalatbari MR, Hamidi M, Moharamzad Y. Pediatric intramedullary cavernous malformation of the conus medullaris: case report and review of the literature. Childs Nerv Syst. 2011;27(3):507511.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Odom GL, Woodhall B, Margolis G. Spontaneous hematomyelia and angiomas of the spinal cord. J Neurosurg. 1957;14(2):192202.

  • 26

    Hernández D, Moraleda S, Royo A, et al. Cavernous angioma of the conus medullaris as a cause of paraplegia. Spinal Cord. 1999;37(1):6567.

  • 27

    Kasliwal MK, Naik V, Kale SS, Sharma BS. Conus cavernoma: a rare cause of spontaneously resolving paraplegia. Surg Neurol. 2008;69(1):103104.

  • 28

    Montano N, Signorelli F, Tufo T, et al. Teaching NeuroImages: extralesional bleeding of conus medullaris cavernoma. Neurology. 2010;75(1):e1.

  • 29

    Obermann M, Gizewski ER, Felsberg J, Maschke M. Cavernous malformation with hemorrhage of the conus medullaris and progressive sensory loss. Clin Neuropathol. 2006;25(2):9597.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 30

    Winkler EA, Lu A, Rutledge WC, et al. A mini-open transspinous approach for resection of intramedullary spinal cavernous malformations. J Clin Neurosci. 2018;58:210212.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 31

    Sandalcioglu IE, Gasser T, Asgari S, et al. Functional outcome after surgical treatment of intramedullary spinal cord tumors: experience with 78 patients. Spinal Cord. 2005;43(1):3441.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Shrivastava RK, Epstein FJ, Perin NI, et al. Intramedullary spinal cord tumors in patients older than 50 years of age: management and outcome analysis. J Neurosurg Spine. 2005;2(3):249255.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Juthani RG, Bilsky MH, Vogelbaum MA. Current management and treatment modalities for intramedullary spinal cord tumors. Curr Treat Options Oncol. 2015;16(8):39.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 34

    Taskiran E, Ulu MO, Akcil EF, Hanci M. Intraoperative neuromonitoring in surgery of cauda equina and conus medullaris tumors. Turk Neurosurg. 2019;29(6):909914.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Rossi C, Boss A, Steidle G, et al. Water diffusion anisotropy in white and gray matter of the human spinal cord. J Magn Reson Imaging. 2008;27(3):476482.

  • 36

    Yiannakas MC, Liechti MD, Budtarad N, et al. Gray vs. white matter segmentation of the conus medullaris: reliability and variability in healthy volunteers. J Neuroimaging. 2019;29(3):410417.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 37

    Nasr AY. Clinical relevance of conus medullaris and dural sac termination level with special reference to sacral hiatus apex: anatomical and MRI radiologic study. Anat Sci Int. 2017;92(4):456467.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation

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