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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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Robert P. Naftel, R. Shane Tubbs, Gavin T. Reed, and John C. Wellons III

The authors describe a new technique that may be used in conjunction with neuronavigation or freehand techniques for obtaining small ventricular access. Using this modification, the introducer sheath and trocar can be guided down a ventriculostomy tract with endoscopic visual control. With increasing focus on endoscopic therapies in patients without hydrocephalus, this adjunct, based on the authors' experience, may provide an additional technique for safely treating patients.

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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, Marios Loukas, James D. Callahan, and Aaron A. Cohen-Gadol

Object

Surgical approaches to the upper anterior thoracic spine can be a challenge. Various techniques such as transsternal routes have been employed but access to the midthoracic vertebrae is limited due to the position of the heart and great vessels. In the present study the authors' goal was to evaluate in cadavers a novel approach to the upper anterior thoracic spine.

Methods

In 12 adult cadavers the majority of the left first rib was removed following infraclavicular transection of the attachment of the anterior and middle scalene muscles from this bone. Inferior retraction of the parietal pleura and lung was performed and dissection was carried out inferior to the left subclavian artery and superior and posterior to the aorta, to the anterior aspect of the upper thoracic spine.

Results

The aforementioned approach and surgical corridor allowed a good access to the anterior aspect of the upper thoracic vertebrae and caudally to the inferior aspect of T-4 vertebral body in all cadavers. No obvious neurovascular injury was identified in any specimen.

Conclusions

To the authors' knowledge, the method described herein has not been previously reported. Based on their cadaveric study, they believe such an approach can be used in the patients with pathology in this region of the thoracic spine. Surgical series are now needed to confirm our findings.

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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, Tyler Marshall, Marios Loukas, Mohammadali M. Shoja, and Aaron A. Cohen-Gadol

Object

The sublime bridge is a potential site of entrapment of the median nerve in the forearm. To the authors' knowledge, this structure and its relationship to the median nerve have not been studied. The aim of the present study was to quantitate this structure and elucidate its relationship to the median nerve.

Methods

Sixty adult cadaveric forearms underwent dissection of the sublime bridge. Relationships of this structure were observed, and measurements of its anatomy were made. The relationship of the median nerve to the sublime bridge was observed with range of motion about the forearm.

Results

The sublime bridge was found to be tendinous in the majority (45 [75%]) of specimens and muscular in the remaining forearms (15 [25%]). The maximal mean width of the sublime bridge was 7 cm proximally, and the minimal mean width was 3 cm distally. The mean distance from the medial epicondyle to the apex of the sublime bridge was found to be 8.1 cm. The relation of the median nerve to the bridge was always intimate. On 2 sides (1 left and 1 right) from different male specimens, the median nerve was attached to the deep aspect of the sublime bridge by a strong connective tissue band, thus forming a tunnel on the deep aspect of this structure. With range of motion of the forearm, increased compression of the median nerve by the overlying sublime bridge was seen with extension but no other movement.

Conclusions

Based on the authors' study, pronator syndrome is an incorrect term applied to compression of the median nerve at the sublime bridge. This potential site of median nerve compression is distinct and has characteristics that can clinically differentiate it from compression of the median nerve between the heads of the pronator teres. The authors hope that these data will be of use to the surgeon in the evaluation and treatment of patients with proximal median nerve entrapment.

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Marios Loukas, Misha Shea, Cory Shea, Martine Lutter-Hoppenheim, Paula Zand, R. Shane Tubbs, and Aaron A. Cohen-Gadol

One hundred years after his death, Jean Baptiste Paulin Trolard's name endures in the medical literature primarily because of his work on the anastomotic veins of the cerebral circulation. Specifically, and known to all neurosurgeons, the great anastomotic vein, or the vein of Trolard, underscores a portion of Trolard's contribution to neuroanatomy. The country of Algeria has also remembered this influential colonist because of his life's work as a physician, professor, humanitarian, environmentalist, and French nationalist. Trolard fought deforestation, injustice, epidemics, and bureaucracy in northern Africa and tragically died in the midst of these struggles. In this historical vignette, the authors review the life and contributions of this pioneer of early neuroanatomy.

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

Object

Knowledge of the anatomy of the ligaments that unite the head with the neck is important to the clinician who treats patients with lesions in this region. Although the anatomy and function of these ligaments have been well described, those of the Barkow ligament (BL) have yet to be studied.

Methods

Via an anterior approach, 13 unembalmed adult cadavers underwent dissection of the craniocervical junction with special attention to the presence, anatomy, and function of the BL.

Results

The BL was found in 92.3% of specimens. The attachment of each ligament onto the medial aspect of the occipital condyle was consistent and just anterior to the attachment of the alar ligaments. In 75% of specimens, there was some connection between the BL and the anterior atlantooccipital membrane. Connections between other adjacent ligamentous structures were not identified. The average width, length, and thickness of the BL were 4, 2.5, and 3.5 mm, respectively. With ranges of motion of the craniocervical junction, only extension of the atlantooccipital joint produced tension in the BL. The mean tension to failure of the ligament was 28 N. Statistical analysis revealed no significant difference in width, length, and thickness of the ligaments based on sex.

Conclusions

The BL was found in all but 1 of our specimens. This ligament appears to resist extension of the atlantooccipital joint and may be synergistic with the anterior atlantooccipital membrane. Interestingly, the function of this ligament as found in this study relies on the integrity of the transverse ligament. Knowledge of this ligament may aid in further understanding craniocervical stability and help in differentiating normal from pathological tissue using imaging modalities.

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Iraj Lotfinia, Payman Vahedi, R. Shane Tubbs, Mostafa Ghavame, and Ali Meshkini

Object

Spinal osteochondromas (OCs) are rare and can originate as solitary lesions or in the context of hereditary multiple exostoses. Concurrent spinal cord compression is a very rare entity. The purpose of this study was to evaluate the authors' 10-year experience with the imaging characteristics and surgical outcome in patients with symptomatic spinal OC.

Methods

Between 1997 and 2007, 8 consecutive cases of symptomatic intraspinal OC with documented spinal cord compression were treated surgically. These patients were analyzed with regard to presentation, imaging, and outcome. The relevant English literature was reviewed using MEDLINE and Google search engines.

Results

Three patients had cervical, 2 had thoracic, and 3 had lumbar lesions. Classic MR imaging characteristics were rarely found. Multiple hereditary exostoses were equally responsible for cervical, thoracic, and lumbar lesions (33%). The origin of the lesion was from the pedicle (25%), lamina (25%), vertebral body (25%), and superior or inferior facets (25%). A posterior approach to the spine was used in 6 patients, and a combined anterior and posterior approach with fusion was performed for 2 thoracic lesions. Surgical outcome was satisfactory in 75% of patients. The prognosis was poor in the patients with thoracic lesions.

Conclusions

In the authors' experience, early detection and surgical removal in cases of symptomatic spinal OC is a key element for the best outcome. Posterior approaches are generally sufficient. The chronicity of symptoms may limit functional recovery postoperatively, especially with cervical and thoracic lesions.

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

Description of and treatment for trigeminal neuralgia has a long history. One pivotal pioneer in this disease, however, has been more or less lost to history, along with his first description of a series of patients treated successfully for trigeminal neuralgia with surgery. John Murray Carnochan, a surgeon practicing in New York City, performed successful neurosurgery on 3 patients some 3 decades earlier than the first commonly accepted successful procedure by William Rose of London in 1890. In the present paper, the authors discuss the life of Dr. Carnochan and his descriptions of patients with trigeminal neuralgia. Based on this review, John Murray Carnochan should properly be remembered as the first surgeon to perform successful neurosurgery for trigeminal neuralgia.