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  • Journal of Neurosurgery: Spine x
  • By Author: Tubbs, R. Shane x
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R. Shane Tubbs, Marios Loukas, Mohammadali M. Shoja, Mohammad Ardalan and W. Jerry Oakes

The 11th century was culturally and medicinally one of the most exciting periods in the history of Islam. Medicine of this day was influenced by the Greeks, Indians, Persians, Coptics, and Syriacs. One of the most prolific writers of this period was Ibn Jazlah, who resided in Baghdad in the district of Karkh. Ibn Jazlah made many important observations regarding diseases of the brain and spinal cord. These contributions and a review of the life and times of this early Muslim physician are presented.

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R. Shane Tubbs, Marios Loukas, Mohammadali M. Shoja, Mohammad R. Ardalan, Nihal Apaydin, Candice Myers, Ghaffar Shokouhi and W. Jerry Oakes

Object

The intradural contributions of the C-4 nerve rootlets have not been previously evaluated for their connections to the brachial plexus. The authors undertook a cadaveric study to evaluate the C-4 contributions to the upper trunk of the brachial plexus.

Methods

The posterior cervical triangles from 60 adult cadavers were dissected. All specimens that were found to have extradural C-4 contributions to the upper trunk of the brachial plexus were excluded from further study. In specimens found to have no extradural C-4 contributions to the brachial plexus a C1–T1 laminectomy was performed. Observations were made of any neural communications between adjacent spinal rootlets, specifically between C-4 and C-5.

Results

Nine (15%) of the 60 sides were found to have extradural C-4 contributions to the upper trunk of the brachial plexus. These sides were excluded from further study. No specimen was found to have a postfixed brachial plexus. Of the remaining 51 sides, 11 (21.6%) were found to have intradural neural connections between C-4 and C-5 dorsal rootlets and 1 (1.96%) had a connection between the ventral roots of C-4 and C-5. Communications between these 2 adjacent dorsal cervical cord levels were of 3 types. Type I was a vertical communication between the more horizontally traveling dorsal roots. Type II was a forked communication between adjacent C-4 and C-5 dorsal rootlets. The Type III designation was applied to connections between ventral rootlets. Although communications were slightly more frequent on left sides, this did not reach statistical significance.

Conclusions

In ~ 20% of normally composed brachial plexuses (those with extradural contributions from only C5–T1) we found intradural C4–5 neural connections. Such variations may lead to misinterpretation of spinal levels in pathological conditions of the spinal axis and should be considered in surgical procedures of this region, such as rhizotomy.

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R. Shane Tubbs, Robert G. Louis Jr., Christopher T. Wartmann, Robert Lott, Gina D. Chua, David Kelly, Cheryl Ann Palmer, Mohamadali M. Shoja, Marios Loukas and W. Jerry Oakes

Object

To the best of the authors' knowledge, no report exists that has demonstrated the histopathological changes of neural elements within the brachial plexus as a result of cervical rib compression.

Methods

Four hundred seventy-five consecutive human cadavers were evaluated for the presence of cervical ribs. From this cohort, 2 male specimens (0.42%) were identified that harbored cervical ribs. One of the cadavers was found to have bilateral cervical ribs and the other a single right cervical rib. Following gross observations of the brachial plexus and, specifically, the lower trunk and its relationship to these anomalous ribs, the lower trunks were submitted for immunohistochemical analysis. Specimens were compared with two age-matched controls that did not have cervical ribs.

Results

The compressed plexus trunks were largely unremarkable proximal to the areas of compression by cervical ribs, where they demonstrated epi- and perineurial fibrosis, vascular hyalinization, mucinous degeneration, and frequent intraneural collagenous nodules. These histological findings were not seen in the nerve specimens in control cadavers. The epineurium was thickened with intersecting fibrous bands, and the perineurium appeared fibrotic. Many of the blood vessels were hyalinized. The nerve fascicles contained frequent intraneural collagenous nodules in this area, and focal mucinous degeneration was identified.

Conclusions

Cervical ribs found incidentally may cause histological changes in the lower trunk of the brachial plexus. The clinician may wish to observe or perform further evaluation in such patients.

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R. Shane Tubbs, Ake Hansasuta, William Stetler, David R. Kelly, Danitra Blevins, Rita Humphrey, Gina D. Chua, Mohammadali M. Shoja, Marios Loukas and W. Jerry Oakes

Object

Few have described the relationship between arachnoid protrusions (villi) and adjacent spinal radicular veins, and the descriptions that do exist are conflicting. Some authors have even denied the presence of spinal arachnoid villi, suggesting that they play no role in cerebrospinal fluid (CSF) absorption.

Methods

To further elucidate these structures, laminectomies from C-2 inferiorly to S-2 were performed in 10 fresh human adult cadavers. Following removal of the laminae, the dural nerve sleeves were identified and the spinal nerves excised 1 cm lateral and medial to the intervertebral foramina. Samples were submitted for histological and immunohistological analysis.

Results

The authors identified arachnoid villi in all specimens. The length of these structures was approximately 50 to 170 μm. Regionally, these villi were more concentrated in the lumbar region, but they were not present at every vertebral level, with observed skip zones. Occasionally, more than one villus was identified per vertebral level. The majority of villi were intimately related to an adjacent radicular vein. There was a direct relationship between the size of the adjacent radicular vein, and the presence and number of arachnoid villi.

Conclusions

Findings in the present study have demonstrated that arachnoid villi exist and are morphologically associated with radicular veins. These data support the theory that CSF absorption occurs not only intracranially but also along the spinal axis. Further animal studies are necessary to prove that CSF traverses these villi and is absorbed into the spinal venous system.

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Sharad Rajpal, M. Shahriar Salamat, R. Shane Tubbs, David R. Kelly, W. Jerry Oakes and Bermans J. Iskandar

Object

The goal of the present study goal was to systematically confirm the previously recognized nomenclature for tethering tracts that are part of the spectrum of occult spinal dysraphic lesions.

Methods

The tethering tract in 20 patients with spina bifida occulta underwent histological examination with H & E staining and epithelial membrane antigen (EMA) immunolabeling, and additional selected specimens were stained with Masson trichrome.

Results

All tethering tracts contained fibrous connective tissue. Four tracts were lined with epithelial cells and either originated within a dermoid cyst, terminated at a skin dimple/sinus opening, or had both of these characteristics. No tethering tracts exhibited EMA positivity or meningeal elements. Although all tethering tracts originated in juxtaposition to the spinal cord, their termination sites were variable.

Conclusions

Based on histological findings and presumed embryological origin, the authors broadly classified tethering tracts terminating within the dura mater, epidural space, or lamina as “short tethering tracts” (STTs). The STTs occurred mostly in conjunction with split cord malformations and had a purely fibrous composition. Tethering tracts terminating superficial to the overlying lamina were classified as “long tethering tracts” (LTTs), and the authors propose that these are embryologically distinct from STTs. The LTTs were of two varieties: epithelial and nonepithelial, the former being typically associated with a skin dimple or spinal cord (epi)dermoid cyst. In fact, analysis of the data suggested that not every tethering tract terminating in or on the skin should be classified as a dermal sinus tract without histological confirmation, and because no evidence of meningeal tissue–lined tracts was detected, the use of the term “meningocele manqué” may not be appropriate.

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Sharad Rajpal, R. Shane Tubbs, Timothy George, W. Jerry Oakes, Herbert E. Fuchs, Mark N. Hadley and Bermans J. Iskandar

Object

Children with spina bifida occulta require early surgery to prevent neurological deficits. The treatment of patients with a congenitally tethered cord who present in adulthood remains controversial.

Methods

The authors studied the medical records of 61 adult patients who underwent surgical untethering for spina bifida occulta at three institutions between 1994 and 2003. Patients who had undergone prior myelomeningocele repair or tethered cord release surgery were excluded.

The most common intraoperative findings were lipomyelomeningocele (41%) and a tight terminal filum (36%). The follow-up duration ranged from 10.8 to 149.5 months. Of the 34 patients with back pain, status improved in 65%, worsened in 3%, remained unchanged in 18%, and improved and later recurred in 15%. Lower-extremity pain improved in 16 patients (53%), remained unchanged in 23%, improved and then recurred in 17%, and worsened in 7%. Lower-extremity weakness improved in 47%, remained unchanged in 47%, and improved and then recurred in 5%. Finally, of the 17 patients with lower-extremity sensory changes, status improved in 35%, remained unchanged in 35%, and the information on five patients was unavailable. Surgical complications included three wound infections, one cerebrospinal fluid leak, and two pseudomeningoceles requiring surgical revision. One patient developed acute respiratory distress syndrome and sepsis postoperatively and died several days later.

Conclusions

Adult-age presentation of a congenital tethered cord is unusual. Despite a slight increase in postoperative neurological injury in adults, surgery has relatively low risk and offers good potential for neurological improvement or stabilization. As they do in children, the authors recommend early surgery in adults with this disorder. The decision to undertake surgery, however, should be modulated by other factors such as a patient's general medical condition and risk posed by anesthesia.

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R. Shane Tubbs, Philip C. Johnson, Mohammadali M. Shoja, Marios Loukas and W. Jerry Oakes

Object

The neurosurgical literature is lacking information on the so-called foramen arcuale. When this foramen is present, the vertebral artery (VA) travels through it after exiting the transverse foramen of the atlas and prior to entering the cranium.

Methods

The authors performed a study in 60 cadavers to determine the incidence of the foramen arcuale and ascertain morphometric information on its anatomy. In specimens in which the foramen arcuale was observed, the authors studied the relationship between it and the VA.

The authors identified a foramen arcuale in 5% of specimens. The mean length and thickness of the osseous struts that converted the groove for the VA into the foramen arcuale were 7.0 and 2.0 mm, respectively. The mean area of the identified foramina was 14.2 mm2. The mean area of the ipsilateral C-1 transverse foramina was 18 mm2 in specimens with a foramen arcuale. The mean measurements of the proximal, intraforaminal (foramen arcuale), and distal diameter of the V3 segment of the VA at the level of the foramen arcuale were 6, 4, and 5 mm, respectively. In all specimens the authors noted that the intraforaminal part of the V3 segment was grossly compressed.

Conclusions

The authors found that the foramen arcuale may compress the V3 segment of the VA. Based on their postmortem study, however, they cannot conclude that compression at this location results in symptomatic VA insufficiency. Based on their review of the literature, it seems that symptomatic compression of the VA at this location may be alleviated in some patients with decompressive procedures.

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R. Shane Tubbs, Marios Loukas, Mohammadali M. Shoja, E. George Salter, W. Jerry Oakes and Jeffrey P. Blount

Object

The authors describe a technique in which the cervical portion of the vagus nerve is exposed during procedures such as neuroma resection or, more commonly, during the placement of a vagus nerve stimulator.

Methods

To test their hypothesis that a posterolateral approach to the vagus nerve may be feasible and efficacious, the authors performed dissection of the left-sided vagus nerve in 13 adult cadavers. The carotid sheath was exposed via the posterior cervical triangle, and the vagus nerve was identified posterolaterally. Measurements were made of the length of available nerve, and the anatomical approach was documented. As part of a comparison study regarding the available length of nerve, the authors exposed the left vagus nerve in five additional adult cadavers via a standard anterior approach to the carotid sheath, and compared the results obtained with each technique.

A mean length of 12 cm of the vagus nerve was isolated when using the posterior approach to the carotid sheath, whereas a mean length of 11 cm of the nerve was documented when using the anterior approach. With the aforementioned posterior approach, no obvious injury occurred to the vagus nerve or other local neurovascular structures such as the spinal accessory nerve.

Conclusions

Evaluation of the findings obtained in the present cadaveric study showed that a posterior approach to the vagus nerve is feasible. The technique for posterior exposure of the carotid sheath may prove useful in surgical exposures of the vagus nerve when a standard anterior method is not possible.

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R. Shane Tubbs, Mohammadali M. Shoja, Leslie Acakpo-Satchivi, John C. Wellons III, Jeffrey P. Blount, W. Jerry Oakes and Bermans J. Iskandar

Object

Surgical exposure of the extracranial part of the vertebral artery (VA) is occasionally necessary. Historically, the greater portion of the extracranial portion of the VA has been approached by traversing the anterior cervical triangle. The authors speculated that this entire segment of the VA could be reached with equal efficacy via the posterior cervical triangle (PCT).

Methods

Six adult cadavers underwent dissection of the left and right VAs via the PCT. The entire extracranial VA was easily exposed through this approach. Only three of 12 sides required the transection of the clavicular head of the sternocleidomastoid muscle for exposure of the most proximal segment of the VA as it originated from the subclavian artery. No gross injury to the VA or other regional vessels or nerves was noted.

Conclusions

The authors found that the extracranial VA can be exposed easily through the PCT. Following confirmation of this technique in vivo, this approach may be added to the surgeon’s armamentarium for exposing the extracranial segment of the VA.

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R. Shane Tubbs, E. George Salter and W. Jerry Oakes

Object

An anomalous vertebral artery (VA) position can jeopardize an otherwise successful procedure, such as a posterior cranial fossa decompression for hindbrain herniation, and may increase the propensity for VA occlusion.

Methods

The authors describe the detailed anatomy of the entrance site of the VA in adult human crania in which there is occipitalization of the atlas. They found that if the atlantal posterior arch or hemiarch was fused to the occiput one should anticipate encountering an anomalous osseous pathway as the VA enters into the cranium, as evidenced by this finding in 80% of their specimens. An anomalous entry pathway was present in all but one left-sided specimen in which the left posterior hemiarch was not fused to the occiput and one right-sided specimen in which there was an unfused and rudimentary posterior arch of the atlas.

Conclusions

The clinician should consider the possibility that the VA takes anomalous routes into the skull in cases in which there is occipitalization of the atlas.