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Paul E. Kim and Manbir Singh

One of the most pertinent applications of the principle primum non nocere (first do no harm) is in the optimization of neurosurgical procedures for patients with resectable lesions. The gold standard for identifying eloquent areas of the brain to be avoided in resections is direct cortical stimulation and somatosensory evoked potential monitoring, which is itself an invasive, cumbersome and difficult technique for mapping these areas. Functional magnetic resonance imaging shows great promise as a viable noninvasive alternative to invasive mapping as well as significant current clinical utility in cases in which it cannot yet fully supplant cortical stimulation methods. Ongoing work is directed toward overcoming technical limitations, improved mapping of complex functions such as language and memory, and mapping of white matter tracts.

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James W. Little, Kim Burchiel and Paul Nutter

✓ A patient is described in whom pain, paresthesias, weakness, and resting tremor gradually developed 8 years after an ulnar nerve transposition. Electromyography revealed that the tremor occurred at 4 to 5 Hz, was abolished by voluntary muscle contraction, and was localized to ulnar-innervated muscles. Ulnar nerve conduction was focally slowed at the elbow; therefore, ulnar neurolysis was performed and a fusiform neuroma-in-continuity was found. Mechanically tapping the neuroma elicited repetitive discharges at 4 to 5 Hz in the intrinsic muscles of the hand; these discharges were abolished by anesthetic block proximal to the neuroma. Although the pain, paresthesias, and weakness were abolished by the neurolysis, the tremor persisted. Possible neurophysiological mechanisms underlying the appearance of tremor with peripheral nerve entrapment are discussed.

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John L. Go, Sandy C. Lee and Paul E. Kim

✓Primary central nervous system lymphoma (PCNSL) is an aggressive neoplastic process that occurs in both immuno-competent and immunocompromised patients. Over the past 30 years there has been a steady increase in the number of cases in both patient populations. The imaging features for the disease and demographic characteristics within these patient populations vary, and in this article the authors describe the salient features of these two groups.

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Phyo Kim, Thoralf M. Sundt Jr. and Paul M. Vanhoutte

✓ The purpose of this study was to examine the hypotheses that structural stiffening of the arterial wall contributes to chronic cerebral vasospasm, and that alteration in properties of smooth muscle takes place after subarachnoid hemorrhage (SAH). Subarachnoid hemorrhage and subsequent chronic vasospasm were induced in dogs by two cisternal injections of autologous blood (on Day 0 and Day 2). Vasospasm was confirmed by angiography performed on Day 0 and Day 7. Animals in the control group underwent angiography only. On Day 8, the mechanical properties of the basilar arteries were studied in vitro. Passive compliance, measured under total inhibition of spontaneous myogenic tone with diltiazem (10−4 M) plus papaverine (10−4 M) was smaller in the SAH group. The length-contraction curve was shifted to the left and the optimum length for maximum contraction (Lmax) was significantly shorter in the spastic blood vessels. The spontaneous myogenic tone was augmented in the SAH group, resulting in an increase in resting tension at each length. By contrast, the maximum contractions in response to KCl and uridine 5′-triphosphate were markedly reduced in the SAH group, without changes in sensitivity to these agents. These differences in mechanical properties were observed in rings both with and without endothelium. The results indicate that, in chronic vasospasm, stiffening of the noncontractile component of the vasculature takes place as well as alterations in the contractile component, both of which presumably contribute to the shift in resting length-tension relationship and length-contraction relationship of the artery. The decreased distensibility, the increase in resting tension, and the shortening of the Lmax all favor a smaller diameter of the artery after SAH, possibly contributing to vasospasm.

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Young H. Kim, Philip L. Gildenberg and Paul M. Duchesneau

✓ A case is reported in which a congenital arteriovenous fistula of the left vertebral artery closed spontaneously 4 years after becoming symptomatic. The course was followed and confirmed by retrograde left brachial angiography.

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Phyo Kim, Thoralf M. Sundt Jr. and Paul M. Vanhoutte

✓ To investigate the alteration of endothelium-dependent responses in chronic vasospasm after subarachnoid hemorrhage (SAH), experiments were carried out in the double-hemorrhage canine model. After the presence of vasospasm was confirmed by cerebral angiography on Days 0 and 7, pharmacological studies on the basilar artery were conducted in vitro on Day 8. In the SAH group, endothelium-dependent relaxation was abolished in response to arginine vasopressin and was significantly reduced in response to thrombin. Endothelium-independent relaxation in the SAH group was preserved in response to papaverine and was minimally reduced in response to sodium nitroprusside. Endothelium-dependent contraction in response to arachidonic acid, acetylcholine, the calcium ionophore A23187, adenosine diphosphate, mechanical stretching, and hypoxia persisted in the SAH group. The maximal contraction to KCl and uridine triphosphate, which is endothelium-independent, was diminished in the SAH group, but no changes in sensitivity were noted in the concentration-response relationships. A significant correlation was observed between the degree of vasospasm determined angiographically and the loss of endothelium-dependent relaxation. The loss of endothelium-dependent relaxation and the persistence of endothelium-dependent contraction suggest that the deterioration in the endothelium-dependent responses may be an important component in the pathogenesis of cerebral vasospasm.

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Paul L. Penar, Jung Kim, Douglas Chyatte and James K. Sabshin

✓ Infection by Cryptococcus neoformans, a budding nonmycelial yeast, involves the central nervous system in 70% of patients at the time of diagnosis. Meningitis and meningoencephalitis are common manifestations of infection; solid granulomas occur but are unusual, and intraventricular granulomas are distinctly rare. Two cases of intraventricular cryptococcal granuloma are reported. The diagnosis and treatment of mass lesions due to cryptococcal infection are discussed, with special reference to intraventricular granulomas.

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Domagoj Coric, Paul K. Kim, Jonathan D. Clemente, Margaret O. Boltes, Marcy Nussbaum and Sara James

Object

The purpose of this study was to evaluate the long-term results of cervical total disc replacement (TDR) and anterior cervical discectomy and fusion (ACDF) in the treatment of single-level cervical radiculopathy.

Methods

The results of 2 separate prospective, randomized, US FDA Investigational Device Exemption pivotal trials (Bryan Disc and Kineflex|C) from a single investigational site were combined to evaluate outcomes at long-term follow-up. The primary clinical outcome measures included the Neck Disability Index (NDI), visual analog scale (VAS), and neurological examination. Patients were randomized to receive cervical TDR in 2 separate prospective, randomized studies using the Bryan Disc or Kineflex|C cervical artificial disc compared with ACDF using structural allograft and an anterior plate. Patients were evaluated preoperatively; at 6 weeks; at 3, 6, and 12 months; and then yearly for a minimum of 48 months. Plain radiographs were obtained at each study visit.

Results

A total of 74 patients were enrolled and randomly assigned to either the cervical TDR (n = 41) or ACDF (n = 33) group. A total of 63 patients (86%) completed a minimum of 4 years follow-up. Average follow-up was 6 years (72 months) with a range from 48 to 108 months. In both the cervical TDR and ACDF groups, mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the minimum 48-month follow-up (p < 0.001). Similarly, the median VAS pain scores improved significantly by 6 weeks and remained significantly improved throughout the minimum 48-month follow-up (p < 0.001). There were no significant differences between groups in mean NDI or median VAS scores. The range of motion (ROM) in the cervical TDR group remained significantly greater than the preoperative mean, whereas the ROM in the ACDF group was significantly reduced from the preoperative mean. There was significantly greater ROM in the cervical TDR group compared with the ACDF group. There were 3 reoperations (7.3%) at index or adjacent levels in the cervical TDR group; all were cervical laminoforaminotomies. There were 2 adjacent-level reoperations in the cervical TDR group (4.9%). There was 1 reoperation (3.0%) in the ACDF group at an index or adjacent level (a second ACDF at the adjacent level). There was no statistically significant difference in overall reoperation rate or adjacent-level reoperation rate between groups.

Conclusions

Both cervical TDR and ACDF groups showed excellent clinical outcomes that were maintained over long-term follow-up. Both groups showed low index-level and adjacent-level reoperation rates. Both cervical TDR and ACDF appear to be viable options for the treatment of single-level cervical radiculopathy.

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Miriam Kim, Paul Nolan and Joel A. Finkelstein

Object. The 11th rib extrapleural—retroperitoneal approach offers an alternative means for access to the thoracolumbar junction. It provides excellent operative exposure without the need to transgress the diaphragm, resulting in less morbidity and reduced risk of pulmonary complications. This approach, however, has been dismissed by many surgeons offering the unsubstantiated criticism that it affords limited access. Thus far, only technical descriptions of the operative procedure are available in the literature, without documentation of the clinical outcomes of these patients.

In the current study the authors describe the 11th rib extrapleural—retroperitoneal approach to the thoracolumbar junction, and they evaluate the associated early and late morbidity in these patients.

Methods. From September 1996 to August 1999, the authors collected prospective data of consecutive patients who underwent surgery for a variety of pathological conditions of the thoracolumbar junction via this approach. In 26 consecutive patients requiring an anterior spinal procedure, lesions located between T-10 and T-11 were studied and followed for a mean period of 17 months (range 1–36 months). There were 13 men and 13 women whose mean age was 47 years (range 16–80 years), with the following pathological entities: trauma (13 cases), neoplasm (six cases), infection (two cases), and deformity (five cases). There were no cases of neurological deterioration. There were no significant pulmonary complications, and only one patient required insertion of a postoperative chest tube.

Conclusions. The 11th rib extrapleural—retroperitoneal approach was successfully used to treat patients with a variety of lesions in the thoracolumbar junction and was associated with little morbidity. The authors believe that previous criticism suggesting that this approach provides only limited access is unsubstantiated.

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Jesse Jones, Alexander Lerner, Paul E. Kim, Meng Law and Patrick C. Hsieh

Cervical spondylotic myelopathy due to ossification of the posterior longitudinal ligament (OPLL) is a common neurosurgical disease that carries high morbidity. OPLL and other degenerative processes cause narrowing of the central canal, with subsequent spinal cord injury. Repeated minor trauma and vascular aberrations have been purported to underlie cervical spondylotic myelopathy, although the exact pathophysiological mechanism is unclear. Regardless, detection of early axonal damage may allow more timely surgical intervention and prediction of functional outcome. Diffusion tensor (DT) imaging of the cervical spine is a novel technique with improved sensitivity compared with conventional anatomical MR imaging that is currently available on most clinical scanners. This review describes the theoretical basis, application, and analysis of DT imaging as it pertains to neurosurgery. Particular emphasis is placed on OPLL.