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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, 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, Joshua M. Beckman, Marios Loukas, Mohammadali M. Shoja and Aaron A. Cohen-Gadol

Object

Various donor nerves have been used for brachial plexus neurotization procedures. To the authors' knowledge, neurotization of median nerve branches to the pronator teres to the radial nerve at the elbow have not been explored.

Methods

In an attempt to identify an additional nerve donor candidate for neurotization procedures of the upper limb, 20 cadaveric upper limbs underwent dissection of the cubital fossa and identification of branches of the median nerve to the pronator teres. Measurements were made of such branches, and distal transection was then performed to determine the appropriate length so that the structure could be brought to the laterally positioned radial nerve via tunneling deep to the biceps brachii muscle.

Results

All specimens were found to have a median nerve branch to the pronator teres that was long enough to reach the radial nerve in the cubital fossa. Neural connections remained tension free with full pronation and supination. The mean length of these branches to the pronator teres was 3.6 cm. The overall mean diameter of these nerves was 1.5 mm. The mean proximal, midpoint, and distal diameters were 2.0, 1.8, and 1.5 mm, respectively. The mean distance between the origin of these branches to the pronator teres and the medial epicondyle of the humerus was 4.1 cm.

Conclusions

Based on the results of our cadaveric study, the use of the branch of the median nerve to the pronator teres muscle may be considered for neurotization of the radial nerve in the cubital fossa.

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R. Shane Tubbs, Cuong J. Bui, Marios Loukas, Mohammadali M. Shoja and W. Jerry Oakes

✓ Cerebral palsy is a common affliction in childhood. In some cases, the spasticity that often occurs can be treated with dorsal rhizotomies. Classically, these procedures have not been performed in children in whom there are known specific congenital brain malformations.

The authors report on two patients with holoprosencephaly and unilateral schizencephaly who underwent dorsal rhizotomy to treat their spasticity. The results were good. The long-term benefits during a mean follow-up period of 3.5 years included the transition from using a walker to quad canes for ambulation. Additionally, the outcomes in these two children appeared comparable to those found in other children with spastic diplegia undergoing dorsal rhizotomy at the authors' institution.

Dorsal rhizotomy may prove useful for treating spasticity in children with known congenital brain deformities.

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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, Martin M. Mortazavi, Mohammadali M. Shoja, Marios Loukas and Aaron A. Cohen-Gadol

Object

Additional nerve transfer options are important to the peripheral nerve surgeon to maximize patient outcomes following nerve injuries. Potential regional donors may also be injured or involved in the primary disease. Therefore, potential contralateral donor nerves would be desirable. To the authors' knowledge, use of the contralateral spinal accessory nerve (SAN) has not been explored for ipsilateral neurotization procedures. In the current study, therefore, the authors aimed to evaluate the SAN as a potential donor nerve for contralateral nerve injuries by using a novel technique.

Methods

In 10 cadavers, the SAN was harvested using a posterior approach, and tunneled subcutaneously to the contralateral side for neurotization to various branches of the brachial plexus. Measurements were made of the SAN available for transfer and of its diameter.

Results

The authors found an SAN length of approximately 20 cm (from transition of upper and middle fibers of the trapezius muscle to approximately 2–4 cm superior to the insertion of the trapezius muscle onto the spinous process of T-12) available for nerve transposition. The average diameter was 2.5 mm.

Conclusions

Based on these findings, the contralateral SAN may be considered for ipsilateral neurotization to the suprascapular and axillary nerves.

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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, Martin M. Mortazavi, Marios Loukas, Mohammadali M. Shoja and Aaron A. Cohen-Gadol

Object

Knowledge of the variations in the nerves of the posterior cranial fossa may be important during skull base approaches. To the authors' knowledge, intracranial neural interconnections between the glossopharyngeal and vagus nerves have not been previously investigated.

Methods

The senior author (A.C.G.) noted the presence of an intracranial interneural connection between the glossopharyngeal and vagus nerves during microvascular decompression surgery in a patient suffering from hemifacial spasm. To further investigate the approximate incidence and significance of such an interneural connection, the authors studied 40 adult human cadavers (80 sides) and prospectively evaluated 16 additional patients during microvascular procedures of the posterior cranial fossa.

Results

In the cadavers, the incidence of intracranial neural connections between the glossopharyngeal and vagus nerves was 2.5%. The only such connection found in our series of living patients was in the patient in whom the connection was initially identified. These interconnections were more common on the left side. Based on our findings, we classified these neural connections as Types I and II. In the cadavers, the length and width of this connection were approximately 9 mm and 1 mm, respectively. Histological analysis of these connections verified their neural content.

Conclusions

Although these connections are rare and the significance is unknown, knowledge of them may prove useful to surgeons who operate in the posterior fossa region so that they may avoid inadvertent traction or transection of these interconnections. Additionally, such connections might be considered in patients with recalcitrant neuralgia after microvascular decompression and rhizotomy of the glossopharyngeal nerve.