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  • By Author: Wellons, John C. x
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R. Shane Tubbs, Eyas M. Hattab, Marios Loukas, Joshua J. Chern, Melissa Wellons, John C. Wellons III, Bermans J. Iskandar and Aaron A. Cohen-Gadol

Object

Endocrine dysfunction following endoscopic third ventriculostomy (ETV) is rare, but it has been reported. In the present study the authors sought to determine the histological nature of the floor of the third ventricle in hydrocephalic brains to better elucidate this potential association.

Methods

Five adult cadaveric brains with hydrocephalus were examined. Specifically, the floors of the third ventricle of these specimens were studied histologically. Age-matched controls without hydrocephalus were used for comparison.

Results

Although it was thinned in the hydrocephalic brains, the floor of the third ventricle had no significant difference between the numbers of neuronal cell bodies versus nonhydrocephalic brains.

Conclusions

Although uncommon following ETV, endocrine dysfunction has been reported. Based on the present study, this is most likely to be due to the injury of normal neuronal cell bodies found in this location, even in very thinned-out tissue.

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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, Marios Loukas, Mohammadali M. Shoja, Ghaffar Shokouhi, John C. Wellons III, W. Jerry Oakes and Aaron A. Cohen-Gadol

Object

Various donor nerves, including the ipsilateral long thoracic nerve (LTN), have been used for brachial plexus neurotization procedures. Neurotization to proximal branches of the brachial plexus using the contralateral long thoracic nerve (LTN) has, to the authors' knowledge, not been previously explored.

Methods

In an attempt to identify an additional nerve donor candidate for proximal brachial plexus neurotization, the authors dissected the LTN in 8 adult human cadavers. The nerve was transected at its distal termination and then passed deep to the clavicle and axillary neurovascular bundle. This passed segment of nerve was then tunneled subcutaneously and contralaterally across the neck to a supra- and infraclavicular exposure of the suprascapular and musculocutaneous nerves. Measurements were made of the length and diameter of the LTN.

Results

All specimens were found to have a LTN that could be brought to the aforementioned contralateral nerves. Neural connections remained tension free with left and right neck rotation of ~ 45°. The mean length of the LTN was 22 cm with a range of 18–27 cm. The overall mean diameter of this nerve was 3.0 mm. No gross evidence of injury to surrounding neurovascular structures was identified in any specimen.

Conclusions

Based on the results of this cadaveric study, the use of the contralateral LTN may be considered for neurotization of the proximal musculocutaneous and suprascapular nerves.

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R. Shane Tubbs, Marios Loukas, Mohammadali M. Shoja, Robert J. Spinner, Erik H. Middlebrooks, William R. Stetler Jr., Leslie Acakpo-Satchivi, John C. Wellons III, Jeffrey P. Blount and W. Jerry Oakes

Object

The suprascapular nerve may become entrapped as it travels deep to the suprascapular ligament, necessitating decompression. The present study was performed to verify the feasibility of a minimally invasive, endoscopically assisted technique for decompressing the suprascapular nerve in the supraspinous fossa.

Methods

The authors performed dissection and decompression of the suprascapular ligament using an endoscopically assisted technique via a 3-cm skin incision in 10 adult cadavers (20 sides). Measurements were also made of the depth from the skin to the suprascapular ligament.

Results

A mean depth of 4 cm was necessary to reach the suprascapular ligament from the skin surface. With the authors' approach, no obvious injury occurred to the suprascapular or other vicinal neurovascular structures (such as the spinal accessory nerve and suprascapular vessels).

Conclusions

The results of this cadaveric study demonstrate that access to the suprascapular nerve can be obtained endoscopically via a small suprascapular incision. This approach obviates a large incision, entry into the glenohumeral joint, and reduces the risk of spinal accessory nerve injury in the posterior cervical triangle, or atrophy of the trapezius or supraspinatus muscles from a standard larger dissection. To the authors' knowledge an endoscopically assisted approach to decompressing the suprascapular nerve as it courses deep to the suprascapular ligament has not been reported previously.

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R. Shane Tubbs, Marios Loukas, Robert G. Louis Jr., Mohammadali M. Shoja, Leslie Acakpo-Satchivi, Jeffrey P. Blount, E. George Salter, W. Jerry Oakes and John C. Wellons III

Object

The superior and inferior sagittal sinuses have been well studied. Interestingly, other venous structures within the falx cerebri have received scant attention in the medical literature. The present study was performed to elucidate the presence and anatomy of these midline structures.

Methods

The authors examined 27 adult latex- or ink-injected cadaveric specimens to observe the morphological features of the sinuses within the falx cerebri (excluding the inferior and superior sagittal sinuses).

Results

All specimens were found to have an extensive network of small tributaries within the falx cerebri that were primarily concentrated in its posterior one third. In this posterior segment, these structures were usually more pronounced in the inferior two thirds. The portion of the falx cerebri not containing significant falcine venous sinus was termed a “safe area.” These vascular channels ranged in size from 0.5 mm to 1.1 cm (mean 0.6 mm); 100% of these vessels communicated with the inferior sagittal sinus. Classification of the structures was then performed based on communication of the falcine venous sinus with the superior sagittal sinus. Type I falcine sinuses had no communication with the superior sagittal sinus, Type II falcine sinuses had limited communication with the superior sagittal sinus, and Type III falcine sinuses had significant communication with the superior sagittal sinus. Seventeen (63%) of 27 specimens communicated with the superior sagittal sinus (Types II and III). Further subdivision revealed 10 Type I, seven Type II, and 10 Type III falcine venous plexuses.

Conclusions

There are other venous sinuses in the falx cerebri in addition to the superior and inferior sagittal sinuses. Neurosurgical procedures that necessitate incising or puncturing the falx cerebri can be done more safely via a described safe area. Given that the majority of specimens in the authors' study were found to have a plexiform venous morphology within the falx cerebri, they propose that these channels be referred to as the falcine venous plexus and not sinus. The falcine venous plexus should be taken into consideration by the neurosurgeon.

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

Object

Facial nerve injury with resultant facial muscle paralysis is disfiguring and disabling. Reanimation of the facial nerve has been performed using different regional nerves. The nerve to the mylohyoid has not been previously explored as a donor nerve for facial nerve reanimation procedures.

Methods

Five fresh adult human cadavers (10 sides) were dissected to identify an additional nerve donor candidate for facial nerve neurotization. Using a curvilinear cervicofacial skin incision, the nerve to the mylohyoid and facial nerve were identified. The nerve to the mylohyoid was transected at its point of entrance into the anterior belly of the digastric muscle. Measurements were made of the length and diameter of the nerve to the mylohyoid, and this nerve was repositioned superiorly to the various temporofacial and cervicofacial parts of the extracranial branches of the facial nerve.

All specimens had a nerve to the mylohyoid. The mean length of this nerve available inferior to the mandible was 5.5 cm and the mean diameter was 1 mm. In all specimens, the nerve to the mylohyoid reached the facial nerve stem and the temporofacial and cervicofacial trunks without tension. No gross evidence of injury to surrounding neurovascular structures was identified.

Conclusions

To the authors' knowledge, the use of the nerve to the mylohyoid for facial nerve reanimation has not been explored previously. Based on the results of this cadaveric study, the use of the nerve to the mylohyoid may be considered for facial nerve reanimation procedures.