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Editorial

Hypertonic saline

Alan Hoffer and Warren R. Selman

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Martin M. Mortazavi, R. Shane Tubbs, Daniel Harmon and W. Jerry Oakes

Chronic emesis may result from a variety of causes. To the authors' knowledge, compression of the area postrema by regional vessels resulting in chronic emesis has not been reported.

The authors report on a child who presented with chronic medically intractable emesis and significant weight loss requiring jejunostomy feeding. Surgical exploration of the posterior cranial fossa found unilateral compression of the area postrema by the posterior inferior cerebellar artery. Microvascular decompression resulted in postoperative and long-term resolution of the patient's emesis.

Although apparently very rare, irritation of the area postrema from the posterior inferior cerebellar artery with resultant medically intractable chronic emesis may occur. Therefore, the clinician should be aware of this potential etiology when dealing with such patients.

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R. Shane Tubbs, Martin M. Mortazavi, Andrew J. Denardo and Aaron A. Cohen-Gadol

The artery of Desproges-Gotteron is rarely mentioned in the literature and is unfamiliar to most neurosurgeons. The authors report a unique case of an arteriovenous malformation (AVM) of the conus in an adult woman, which received blood supply from an artery of Desproges-Gotteron. The patient presented with intermittent pain radiating down the right posterior thigh and foot and transient bladder incontinence. On examination, there was weakness of the right lower limb with hypalgesia of the plantar aspect of the right foot. Magnetic resonance imaging revealed a mass near the anterior aspect of the conus medullaris and angiography confirmed a spinal AVM at the L-1 level and a shunt located at the inferior L-3 level. The patient underwent transarterial embolization, and at 2-year follow-up, repeat angiography demonstrated no evidence of residual or recurrent spinal AVM, intermittent and tolerable pain without treatment interventions, and a normal neurological examination. The artery of Desproges-Gotteron appears to be a rare arterial variation. Moreover, the authors believe this to be the first case of a conal AVM supplied by such an artery. The anatomy and implications of such an arterial variant are discussed.

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Martin Mortazavi, Aman Deep, R. Shane Tubbs and Wink S. Fisher III

Manuscript submitted May 23, 2011. Accepted September 25, 2011. Kenneth Grant Jamieson is celebrated as one of Australia's top neurosurgeons. His most notable contributions to neurosurgery included novel treatments of aneurysms and pineal tumors and studies of head injury. Jamieson was also an innovator for the development of new neurosurgical instruments and renowned for his teaching abilities, prolificacy, and mentorship. This preeminent neurosurgeon's life was cut short at the age of 51. Our current understanding and knowledge of treatments of various neurosurgical diseases is based on pioneers such as Kenneth Grant Jamieson.

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Martin M. Mortazavi, Andrew K. Romeo, Aman Deep, Christoph J. Griessenauer, Mohammadali M. Shoja, R. Shane Tubbs and Winfield Fisher

Object

Currently, mannitol is the recommended first choice for a hyperosmolar agent for use in patients with elevated intracranial pressure (ICP). Some authors have argued that hypertonic saline (HTS) might be a more effective agent; however, there is no consensus as to appropriate indications for use, the best concentration, and the best method of delivery. To answer these questions better, the authors performed a review of the literature regarding the use of HTS for ICP reduction.

Methods

A PubMed search was performed to locate all papers pertaining to HTS use. This search was then narrowed to locate only those clinical studies relating to the use of HTS for ICP reduction.

Results

A total of 36 articles were selected for review. Ten were prospective randomized controlled trials (RCTs), 1 was prospective and nonrandomized, 15 were prospective observational trials, and 10 were retrospective trials. The authors did not distinguish between retrospective observational studies and retrospective comparison trials. Prospective studies were considered observational if the effects of a treatment were evaluated over time but not compared with another treatment.

Conclusions

The available data are limited by low patient numbers, limited RCTs, and inconsistent methods between studies. However, a greater part of the data suggest that HTS given as either a bolus or continuous infusion can be more effective than mannitol in reducing episodes of elevated ICP. A meta-analysis of 8 prospective RCTs showed a higher rate of treatment failure or insufficiency with mannitol or normal saline versus HTS.

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Christoph J. Griessenauer, R. Shane Tubbs, Mohammadali M. Shoja, Joel Raborn, Christopher J. Boes, Martin M. Mortazavi and Giuseppe Lanzino

Alfred W. Adson was a pioneer in the field of neurosurgery. He described operations for a variety of neurosurgical diseases and developed surgical instruments. Under his leadership the Section of Neurological Surgery at the Mayo Clinic was established and he functioned as its first chair. Adson's contributions to the understanding of spinal and spinal cord tumors are less well known. This article reviews related medical records and publications and sets his contributions in the context of the work of other important pioneers in spinal tumor surgery at the time.

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

Object

Knowledge of the detailed anatomy of the craniocervical junction is important to neurosurgeons. To the authors' knowledge, no study has addressed the detailed anatomy of the intracranial (first) denticulate ligament and its intracranial course and relationships.

Methods

In 10 embalmed and 5 unembalmed adult cadavers, the authors performed posterior dissection of the craniocervical junction to expose the intracranial denticulate ligament. Rotation of the spinomedullary junction was documented before and after transection of unilateral ligaments.

Results

The first denticulate ligament was found on all but one left side and attached to the dura of the marginal sinus superior to the vertebral artery as it pierced the dura mater. The ligament always traveled between the vertebral artery and spinal accessory nerve. On 20% of sides, it also attached to the intracranial vertebral artery and, histologically, blended with its adventitia. In general, this ligament tended to be thicker laterally and was often cribriform in nature medially. The hypoglossal nerve was always superior to the ligament, which always concealed the ventral roots of the C-1 spinal nerve. The posterior spinal artery traveled posterior to this ligament on 93% of sides. On one left side, the ascending branch of the posterior spinal artery traveled anterior to the ligament and the descending branch traveled posterior to it. Following unilateral transection of the intracranial denticulate ligament, rotation of the spinomedullary junction was increased by approximately 25%.

Conclusions

Knowledge of the relationships of the first denticulate ligament may prove useful to the neurosurgeon during procedures at the craniocervical junction.

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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.

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R. Shane Tubbs, Martin M. Mortazavi, Marios Loukas, Anthony V. D'Antoni, Mohammadali M. Shoja and Aaron A. Cohen-Gadol

Object

The nerves of the posterior neck are often encountered by the neurosurgeon and are sometimes the focus of denervation procedures for muscular, joint, or nervous pathologies. One collection of fibers in this region that has not been previously investigated is the Cruveilhier plexus, interneural connections between the dorsal rami of the upper cervical nerves.

Methods

Fifteen adult cadavers (30 sides) were subjected to dissection of the upper cervical and occipital regions with special attention given to identifying potential connections between adjacent extradural dorsal rami of the cervical nerves. When connections were identified, measurements were made and random samples were immunohistochemically stained.

Results

At least one communicating branch was identified on 86.7% of sides. Sampled nervous loops were composed primarily of sensory fibers, but occasional motor fibers were identified. For C-1, a communicating loop joined the medial branches of C-2 on 65.4% of sides. On 29.4% of sides, this loop pierced the obliquus capitis inferior muscle before joining C-2. On 54% of sides, a communicating loop joined the medial branches of the dorsal rami of C-2 and C-3; and on 15.4% of sides, a communicating loop joined the medial branches of the dorsal rami of C-3 and C-4. No specimen had communicating branches between the dorsal rami of cervical nerves C-5 to C-8. Articular branches arose from the deep surface of the interneural connections as they crossed the adjacent facet joint on 34.6% of sides. Loops giving rise to fibers that terminated into surrounding musculature were seen on 35% of sides.

Conclusions

Physical examinations that reveal unexpected results, such as altered sensory dermatome findings, may be attributed to the Cruveilhier plexus. Based on findings in the present study, surgical procedures, such as those aimed at completely denervating the upper posterior cervical musculature, facets, or nerves supplying the skin of the occiput, must also transect the Cruveilhier plexus.