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R. Shane Tubbs, Isaiah Tubbs, Marios Loukas and Aaron A. Cohen-Gadol

OBJECT

Additional distal sites for placement of CSF diversionary shunts may be necessary in some patients. The present study aimed to investigate the marrow space of the ilium as a potential receptacle for CSF in patients with hydrocephalus.

METHODS

Cannulation of the marrow space of the ilium was performed in 5 fresh human cadavers less than 4 hours from time of death. Tap water was infused via a metal trocar for approximately 60 minutes.

RESULTS

A total of 30 L of water was easily injected into all cadaveric specimens without overflow from the infusion site or noticeable edema of the body. Upon inspection of the thoracic and abdominal cavities, no fluid accumulation was identified, ensuring that all infused fluid had gone into the vascular system.

CONCLUSIONS

Based on this cadaveric study, the ilium appears to be an ideal location for placement of the distal end of a CSF diversionary shunt when other anatomical receptacles are not an option. In vivo human studies are now required to verify these findings.

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R. Shane Tubbs, Mohammadali M. Shoja, Marios Loukas, W. Jerry Oakes and Aaron Cohen-Gadol

William Henry Battle (1855–1936) practiced medicine in England > 1 century ago and is primarily remembered for his description of ecchymosis over the mastoid, which indicates fracture of the skull base. Although Mr. Battle made many contributions to medicine, almost nothing exists in the literature regarding his life and findings, especially in regard to head injury. The following is a review of Battle's background and his contributions to medicine, specifically his observations associated with basilar skull fractures.

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R. Shane Tubbs, Marios Loukas, Joshua Dixon and Aaron A. Cohen-Gadol

Object

Occasionally, the internal carotid artery (ICA) may be symptomatically compressed in the neck by an elongated styloid process. The authors are unaware, however, of any study to date in which the aim was to describe the compression of this part of the ICA by surrounding muscles extending from the styloid process.

Methods

In 20 adult cadavers (40 sides), dissection of the cervical ICA was performed, with special attention given to the relationship between this artery and the stylopharyngeus muscle. In addition, rotation of the head was performed while observing for any compression of the ICA by this muscle. Last, the segment of the ICA immediately adjacent to the stylopharyngeus was excised and evaluated for signs of gross compression.

Results

Five sides (12.5%) were found to have an ICA that was grossly compressed by the neighboring stylopharyngeus muscle, and this was confirmed on excised ICA specimens. Moreover, such compression was increased with ipsilateral rotation of the head. Effacement of the lumen of the ICA by the stylopharyngeus ranged from approximately 30 to 50%. Such compression was increased by approximately 25% with ipsilateral rotation of the head.

Conclusions

To the authors' knowledge, compression of the cervical ICA by the stylopharyngeus muscle has not been previously described. Such a relationship should be appreciated by the clinician who treats patients with symptoms of ICA stenosis or occlusion as a potential extracranial site of compression. Based on this study, a subset of patients with occlusion of the cervical ICA but without elongation of the styloid process should be included within the definition of Eagle syndrome.

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R. Shane Tubbs, Marios Loukas, Mohammadali M. Shoja, Ghaffar Shokouhi and W. Jerry Oakes

✓François Magendie lived during a tumultuous period in French history. Although this early medical pioneer made significant contributions to the fields of neuroanatomy, physiology, and pharmacology, little information is found in the non-French literature regarding this significant person in history. Based on this review, one could also consider this trained surgeon as an early pioneer of neurosurgery. For example, he is known to have used Galvanic current to treat various neuralgias, described a technique for extracting cerebrospinal fluid and quantitated and described its characteristics in normal and pathological specimens, and elucidated the functions of the the cranial nerves using vivisection. Additionally, he accurately described the functions of the dorsal and ventral rootlets using vivisection, and realized that the exposed meninges were susceptible to painful stimuli. Our current knowledge is based on the early contributions of scientists such as François Magendie.

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R. Shane Tubbs, Matthew R. Levin, Marios Loukas, Eric A. Potts and Aaron A. Cohen-Gadol

Object

To date, only scant descriptions of the cluneal nerves are available. As these nerves, and especially the superior group, may be encountered and injured during posterior iliac crest harvest for spinal arthrodesis procedures, the present study was performed to better elucidate their anatomy and to provide anatomical landmarks for their localization.

Methods

The superior and middle cluneal nerves were dissected from their origin to termination in 20 cadaveric sides. The distance between the posterior superior iliac spine (PSIS) and superior cluneal nerves at the iliac crest and the distance between this bony prominence and the origin of the middle cluneals were measured. The specific course of each nerve was documented, and the diameter and length of all cluneal nerves were measured.

Results

Superior and middle cluneal nerves were found on all sides. An intermediate superior cluneal nerve and lateral superior cluneal nerve were not identified on 4 and 5 sides, respectively. The superior cluneal nerves always passed through the psoas major and paraspinal muscles and traveled posterior to the quadratus lumborum. The mean diameters of the superior and middle cluneal nerves were 1.1 and 0.8 mm, respectively. From the PSIS, the superior cluneal branches passed at means of 5, 6.5, and 7.3 cm laterally on the iliac crest. At their origin, the middle cluneal nerves had mean distances of 2 cm superior to the PSIS, 0 cm from the PSIS, and 1.5 cm inferior to the PSIS. In their course, the middle cluneal nerves traversed the paraspinal muscles attaching onto the dorsal sacrum.

Conclusions

Knowledge of the cutaneous nerves that cross the posterior aspect of the iliac crest may assist in avoiding their injury during bone harvest. Additionally, an understanding of the anatomical pathway that these nerves take may be useful in decompressive procedures for entrapment syndromes involving the cluneal nerves.

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R. Shane Tubbs, Anand N. Bosmia, Marios Loukas, Eyas M. Hattab and Aaron A. Cohen-Gadol

Object

Although it is often visualized surgically, details regarding the inferior medullary velum are lacking in the literature. The present study is intended to better elucidate this neuroanatomical structure using microsurgical and immunohistochemical analyses.

Methods

To study the inferior medullary velum, the authors performed microdissection in 15 adult cadavers. Following gross study, specimens were examined histologically.

Results

The inferior medullary velum extended from the flocculus to the middle cerebellar peduncle and stretched between the inferior cerebellar peduncle and the nodule and pyramid. The average thickness of the velum was found to be 0.5 mm (range 0.35–0.8 mm) and the average length was found to be 6 mm (range 5.5–7.2 mm). Arterial branches were identified in all specimens that arose from medullary branches of the posterior inferior cerebellar artery and supplied the inferior medullary velum. Histologically and from internal to external, a choroid plexus epithelium as a single cell layer was adjacent to a cuboidal layer of ependymal cells with no visible cilia. The next layer contained scattered glia in single cells or small clusters. The most external layer was composed of flat spindle cells resembling fibroblasts. No neurons of any type were identified. Only rare axons traversed the thin hypocellular zone that disappeared toward the midline.

Conclusions

Based on this cadaveric study, the authors conclude that division of the inferior medullary velum should be relatively harmless as no neuronal cells were identified in this structure, which appears to be a vestigial bridge of tissue between the left and right sides of the cerebellum.

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R. Shane Tubbs, Marios Loukas, Michael Hill, Mohammadali M. Shoja and Aaron A. Cohen-Gadol

Richard Lower (1631–1691), an anatomist and physician, was born in St. Tudy, Cornwall, England, and became an avid follower of William Harvey and a pupil to Sir Thomas Willis. Unfortunately, little is written of his contributions to the study of the nervous system despite his successful medical career and his regard as one of the most significant English physiologists of the 17th century. Lower was best known for his remarkable studies within the cardiovascular and respiratory disciplines. However, although not as well documented and thus often overlooked, Lower produced noteworthy advancements within the field of neuroscience such as studying the hindbrain innervation of the heart, CSF formation and circulation, cranial nerve function, and the structural sources of seizures. Some have even attributed the results of Willis' anatomical and physiological studies to Lower rather than to Willis himself. Lower has not received the recognition he is owed as a highly skilled and trained anatomist and physician. In this paper, the neurological contributions, with a brief mention of challenges, delivered during the 17th century by this influential historical physician will be highlighted with an emphasis on the impact each contribution made.

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R. Shane Tubbs, Marios Loukas, Mohammadali M. Shoja, John C. Wellons and Aaron A. Cohen-Gadol

Object

Cadavers are often used in the teaching of various neurosurgical procedures. One aspect of this resource that has not been previously explored is the postmortem dilation of the ventricular system, which is often collapsed, for the purpose of training neurosurgeons in the use of intraventricular endoscopy.

Methods

Nine adult cadavers without a history of hydrocephalus or other known intracranial pathology were used for this study. Four specimens were obtained post embalming, and 5 specimens were fresh (time from death until the procedure < 5 hours). In all cadavers catheters were placed into the lateral ventricles; saline and then air were injected into the ventricles through the catheters. Ventriculostomy sites were filled with rubber stoppers, and in fresh specimens, formal embalming was performed with cadavers in the Trendelenburg position. Lastly, serial horizontal sectioning of the cranium was performed in all cadavers to verify ventricular dilation.

Results

None of the 4 embalmed specimens were found to have ventriculomegaly following injection. However, this condition was found in 4 of the 5 fresh specimens. In the single fresh cadaver without ventriculomegaly, the cause of death had been massive intracranial subarachnoid hemorrhage, which distorted the ventricular system. This may have prevented cannulation of the ventricle and ventricular expansion in this specimen.

Conclusions

The ventricular system of fresh human cadavers can be dilated postmortem. The method described herein may be useful to neurosurgical trainees or those trained neurosurgeons wishing to practice intraventricular endoscopy.

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R. Shane Tubbs, Joshua Dixon, Marios Loukas and Aaron A. Cohen-Gadol

Object

The foramen ovale and its neighboring vascular structures may be seen via external approaches to the skull base. More commonly, however, transcutaneous approaches to the foramen ovale are performed. Although complications with this latter technique are uncommon, studies of the distances to the surrounding extracranial vascular structures are lacking in the literature. The present study aimed to elucidate such anatomical relationships.

Methods

Twenty adult cadavers (40 sides) underwent dissection of the region surrounding the foramen ovale at the external skull base. Measurements between the external surface of the foramen ovale and surrounding vascular structures were made.

Results

From the nearest aspect of the undersurface of the foramen ovale, the authors found that the mean distances to the middle meningeal artery, maxillary artery, superior bulb of the internal jugular vein, and internal carotid artery at its entrance to and exit from the carotid canal were 3, 19, 20, 9, and 12 mm, respectively. Distances tended to be shorter in females, but this did not reach statistical significance. On the basis of these data, the authors also determined a safe zone while approaching the undersurface of the foramen ovale.

Conclusions

Additional knowledge of the neurovascular relationships surrounding the foramen ovale may be useful to the neurosurgeon and may help decrease the potential for complications.

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R. Shane Tubbs, Mark Hill, Marios Loukas, Mohammadali M. Shoja and W. Jerry Oakes

Object

Many authors have concluded that the Chiari malformation Type I (CM-I) is due to a smaller than normal posterior cranial fossa. In order to establish this smaller geometry as the cause of hindbrain herniation in a family, the authors of this paper performed volumetric analysis in a family found to have this malformation documented in 4 generations.

Methods

Members from this family found to have a CM-I by imaging underwent volumetric analysis of their posterior cranial fossa using the Cavalieri method.

Results

No member of this family found to have CM-I on preoperative imaging had a posterior fossa that was significantly smaller than that of age-matched controls.

Conclusions

The results of this study demonstrate that not all patients with a CM-I will have a reduced posterior cranial fossa volume. Although the mechanism for the development of hindbrain herniation in this cohort is unknown, this manifestation can be seen in multiple generations of a familial aggregation with normal posterior fossa capacity.