Malignant Melanotic Nerve Sheath Tumor.

Malignant melanotic nerve sheath tumors are uncommon pigmented tumors of Schwann cell origin, most often found along the spinal nerves. Although well-described in the literature, the tumors are quite rare, making up <1% of nerve sheath tumors. Physicians are, therefore, often unfamiliar with both the appearance and the optimal treatment of such tumors. Morphologically, many imaging features overlap with schwannomas and neurofibromas. Nevertheless, the malignant melanotic nerve sheath tumors are crucial to identify. They can be extremely aggressive, and the management of these tumors is considerably different from their benign counterparts. In this radiology-pathology review, we will highlight the imaging appearance, histologic features, surgical resection, and subsequent therapeutic strategies in a patient with a lumbar malignant melanotic nerve sheath tumor.

MR spectroscopy differences between lipomatosis of nerve and neuromuscular choristoma: a potential adjunctive diagnostic tool.

OBJECTIVE: To describe differences between lipomatosis of nerve (LN) and neuromuscular choristoma (NMC) evaluated with MR spectroscopy (MRS). MATERIALS AND METHODS: Eight patients were included in this prospective pilot study: three patients with LNs and five with NMCs. Single voxel PRESS MRS of the tumors were acquired with 3 T MRI. MRS data were processed with LCModel version 6.3-1J using the internal "lipid-8" basis set. From individual lipid peak and water content measurements, total fatty acid molecules (TFAM), unsaturated fatty acid molecules (UFAM), and glycerol molecules (GM) were computed and analyzed, as well as ratios of UFAM/TFAM, TFAM/GM, and a fatty-acid chain-length index (CLI). RESULTS: The LN group included two men and one woman (average age 58.3 years); the NMC group included two men and three women (average age 20.4 years). Lipid composition analysis showed that LN had considerably more fat than NMC: TFAM: LN = 15.29 vs NMC = 7.14; UFAM: LN = 4.48 vs NMC = 2.63; GM: LN = 5.20 vs NMC = 1.02. Both tumors had a similar fraction of unsaturated fatty acids: UFAM/TFAM: LN = 0.29 vs NMC = 0.37. LN had the usual number of FA molecules/glycerol molecule, while NMC had considerably more: TFAM/GM: LN = 2.94 vs NMC = 6.98. Finally, average FA chains were longer in NMC: CLI: LN = 17.39 vs NMC = 22.55. CONCLUSION: Our analysis suggests measurable differences in the amount and composition of lipid in LN and NMC. While a larger, statistically powered study is needed, these initial findings may be helpful to properly diagnose ambiguous cases and thereby avoid surgical intervention such as biopsy.

Sonographic evaluation of the lateral femoral cutaneous nerve in meralgia paresthetica.

OBJECTIVE: Identify sonographic features of the lateral femoral cutaneous nerve (LFCN) in meralgia paresthetica (MP) and report therapeutic outcomes in sonographically confirmed cases. MATERIALS AND METHODS: Retrospective review of 50 patients with clinically suspected MP and 20 controls. Ultrasounds were reviewed for characteristics of the LFCN and compared between groups. When available, MRIs were reviewed. In cases of sonographically pathologic LFCN, subsequent therapeutic interventions were recorded. RESULTS: Thirty-five of the suspected MP cases (70%) had ultrasound findings suggestive of MP, 10 (20%) were negative, and in 5 (10%) the LFCN was not seen. Sonographic findings in positive cases included nerve enlargement in all cases (mean cross-sectional area 9 mm2 (standard deviation (SD) ± 5.59) versus 4 mm2 (SD ± 2.31) and 3 mm2 (SD ± 2.31) in negative cases and normal controls, respectively; p < 0.01), nerve hypoechogenicity (30 of 35 cases, 86%), and focal lesion (7 of 35 cases, 20%). Sixteen ultrasounds positive for MP had MRIs with only 4 (25%) reporting a concordant LFCN abnormality (enlargement or T2 hyperintensity). Twenty-five of the 35 (71%) patients with positive sonographic findings for MP had a US-guided LFCN block (local anesthetic ± corticosteroid), with 24 of 25 (96%) patients reporting immediate symptomatic improvement. Eighteen of 35 (51%) underwent LFCN neurectomy or neurolysis, all of whom experienced symptomatic improvement. CONCLUSION: Ultrasound is a useful modality for LFCN assessment in clinically suspected MP and is more sensitive for abnormalities than MRI. Nearly all patients who received perineural analgesia and/or neurectomy or neurolysis had symptomatic improvement.

Benign metastasizing leiomyomatosis with massive brachial plexus involvement mimicking neurofibromatosis type 1.

We report the case of a patient who presented with right arm and shoulder pain due to compression of the infraclavicular brachial plexus due to benign metastasizing leiomyomatosis (BML). She was initially and had been repeatedly misdiagnosed as having neurofibromatosis type 1 (NF 1). The diagnosis of BML was not obvious due to its rare nature, the patient's not detailing the specifics of her gynecologic history of having undergone resection of a large uterine leiomyoma and followed by disseminated pelvic leiomyomatous nodules, histologic misinterpretation of an extrauterine lesion of the spine and the brachial plexus as a neurofibroma and the radiologic diagnosis of lung nodules as being "non-specific" in nature. In addition and importantly, no clinical, radiographic or histologic features of NF 1 were present. Although a rare condition, BML should be considered in the differential diagnosis of NF and in patients having a history of uterine leiomyoma. The remarkable, selective involvement of the brachial plexus in this case is unexplained.

Connective tissue dysplasia in five new patients with NF1 microdeletions: further expansion of phenotype and review of the literature.

Approximately 5% of patients with neurofibromatosis type 1 (NF1) have deletions of the entire NF1 gene. The phenotype usually includes early onset, large number of neurofibromas, presence of congenital anomalies, cognitive deficiency, and variable dysmorphic features and growth abnormalities. Connective tissue abnormalities are not generally recognised as a part of NF1 microdeletion syndrome, but mitral valve prolapse, joint laxity, and/or soft skin on the palms have been reported in a few patients. We describe clinical findings in six newly diagnosed patients with NF1 microdeletions, five of whom presented with connective tissue abnormalities. A literature review of the clinical findings associated with NF1 microdeletion was also performed. Our report confirms that connective tissue dysplasia is common in patients with NF1 microdeletions. Given the potential for associated cardiac manifestation, screening by echocardiogram may be warranted. Despite the large number (>150) of patients with known NF1 microdeletions, the clinical phenotype remains incompletely defined. Additional reports of patients with NF1 microdeletions, including comprehensive clinical and molecular information, are needed to elucidate possible genotype-phenotype correlation.

Chronic immune sensory polyradiculopathy: a possibly treatable sensory ataxia.

BACKGROUND: Chronic inflammatory neuropathies can present with a sensory ataxia due to involvement of dorsal root ganglia (DRG) or sensory nerves. Selective inflammatory involvement of sensory nerve roots proximal to the DRG has been postulated. METHODS: The authors identified 15 patients with a sensory syndrome and normal nerve conduction studies. Sensory nerve root involvement was suggested by either somatosensory evoked potential (SSEP) or imaging abnormalities. CNS disease was excluded. RESULTS: All patients had gait ataxia, large fiber sensory loss, and paresthesias, and nine had frequent falls. The disease course was chronic and progressive (median duration 5 years, range 3 months to 18 years). Sural sensory nerve action potential amplitudes were preserved and SSEP abnormalities were consistent with sensory nerve root involvement. Five patients had enlargement of lumbar nerve roots on MRI with enhancement in three. The CSF protein was elevated in 13 of 14 patients tested. Three patients had lumbar sensory rootlet biopsies that showed thickened rootlets, decreased density of large myelinated fibers, segmental demyelination, onion-bulb formation, and endoneurial inflammation. Six patients who required aids to walk were treated with immune modulating therapy and all had marked improvement with four returning to normal ambulation. CONCLUSION: Based on the described clinical features, normal nerve conduction studies, characteristic somatosensory evoked potential (SSEP) abnormality, enlarged nerve roots, elevated CSF protein, and inflammatory hypertrophic changes of sensory nerve rootlet tissue, we suggest the term chronic immune sensory polyradiculopathy (CISP) for this syndrome. This condition preferentially affects large myelinated fibers of the posterior roots, may respond favorably to treatment, and may be a restricted form of chronic inflammatory demyelinating polyradiculoneuropathy.

Medial or lateral dislocation (snapping) of a portion of the distal triceps: a biomechanical, anatomic explanation.

Medial and lateral snapping (dislocation) of the distal triceps over the epicondyle during elbow flexion has been reported but is frequently misdiagnosed and is not well understood. In this study a mathematical model was designed to simulate the effect that bony abnormalities at the distal humerus and soft tissue variations of the distal triceps have on the line of pull of the triceps. The predictions were then tested on prefabricated and fabricated plastic elbow models, as well as 8 cadaveric elbows. When the bony alignment was altered, varus angulation had the greatest effect: 30 degrees varus malalignment of the distal humerus displaced the centroid of the triceps vector medially by approximately 2.0 cm. Valgus malalignment had a lesser effect: 30 degrees valgus displaced it laterally by 1.5 cm. Negligible effects on the triceps line of pull were seen with internal or external malrotation and with flexion or extension malalignment. Of the soft tissue alterations, displacement of the triceps insertion had a greater effect than movement of the triceps origin. The triceps vector was displaced by approximately 70% of the amount of translation of the triceps insertion. The relationship between the triceps line of pull and the bony alignment is represented by the triceps (T) angle. Our use of the T angle to understand snapping triceps is analogous to the use of the quadriceps (Q) angle for patellar subluxation/dislocation. Treatment should aim to restore normal triceps biomechanics with soft tissue or bony procedures.

Hemi-contralateral C7 transfer to median nerve in the treatment of root avulsion brachial plexus injury.

Because of the poor clinical results in achieving hand function in patients with complete brachial plexus root avulsion with other nerve transfers, we evaluated 111 patients prospectively to evaluate the technique of the hemi-contralateral C7 transfer to the median nerve. The transfer was performed as a primary procedure in 62 patients and as a secondary procedure in additional 49 patients. Twenty-one of the 62 patients in the primary group had sufficient follow-up (at least 3 years) to assess the motor and sensory recovery in the median nerve. The adverse effects of the operation were also analyzed in all 111 patients. Six of the 21 (29%) patients obtained M3 and 4 (19%) experienced M2 recovery of the wrist and finger flexors. Ten (48%) patients obtained S3 and 7 (33%) had S2 recovery in the median nerve area. The rate of the advancing Tinel's sign was markedly different between those achieving M3 function and the remaining patients. Although the age of the patient did not correlate with outcome, patients aged 18 and younger had the best motor recovery (ie, achieving M3 function in 3 of 6 cases). There was no correlation between the timing of the surgery after the initial injury, medical comorbidities, and clinical outcome. After surgery 108 of 111 (97%) patients experienced temporary paresthesia in the median nerve area, which resolved by an average of 2.8 months. Three (3%) patients had motor weakness of the donor limb; this resolved completely in 2 patients and left a mild deficit in wrist extension in 1 patient.

Tardy posterolateral rotatory instability of the elbow due to cubitus varus.

BACKGROUND: Cubitus varus has long been considered merely a cosmetic deformity. The purpose of this paper is to demonstrate a causal relationship between cubitus varus and instability of the elbow. METHODS: In twenty-four patients (twenty-five limbs) with a cubitus varus deformity following a pediatric distal humeral fracture or resulting from a congenital anomaly (three limbs of two patients), tardy posterolateral rotatory instability of the elbow developed approximately two to three decades after the deformity occurred. All patients presented with lateral elbow pain and recurrent instability. The average varus deformity was 15 degrees (range, 0 degrees to 35 degrees ). Surgery was performed in twenty-one patients (twenty-two limbs). Treatment consisted of reconstruction of the lateral collateral ligament and osteotomy in seven limbs, ligament reconstruction alone in ten, osteotomy alone in four, and total elbow arthroplasty in one. RESULTS: In three patients, the triceps muscle was dynamically stimulated intraoperatively to contract while resisting extension of the elbow. This produced posterolateral rotatory subluxation of the elbow, which was reversed by corrective osteotomy and lateral transposition of a portion of the medial head of the triceps that originally had been attached to the elongated, deformed medial aspect of the olecranon. At an average of three years (minimum, one year) after the operation, the result was good or excellent for nineteen of the twenty-two limbs that had undergone an operation; three limbs had persistent instability. CONCLUSIONS: With cubitus varus, the mechanical axis, the olecranon, and the triceps line of pull are all displaced medially. The repetitive external rotation torque on the ulna permitted by these deformities can stretch the lateral collateral ligament complex and lead to posterolateral rotatory instability. Thus, cubitus varus deformity secondary to supracondylar malunion or congenital deformity of the distal part of the humerus may not always be a benign condition and may have important long-term clinical implications. Operative correction can relieve symptoms of instability. The indications for preventive corrective osteotomy remain to be determined.

100 years of neurological surgery at the Mayo Clinic.

The practice of neurological surgery at the Mayo Clinic began as early efforts were undertaken by Drs. Charles Mayo and Emil Beckman, and surgical procedures were performed for trauma, infection, tumor, epilepsy, and hemorrhage. In 1919, the Section of Neurologic Surgery was established, with Alfred W. Adson as its first chair. Subsequently, Drs. Winchell McK. Craig, J. Grafton Love, Collin S. MacCarty, Ross H. Miller, and Thoralf M. Sundt, Jr., followed as eminent chairmen. Beginning with a modest number of cases per year, the neurosurgical service at the Mayo Clinic has grown to become one of the largest in North America. Under the current leadership of Dr. David G. Piepgras, approximately 3200 surgical procedures spanning the spectrum of subspecialties are performed each year by a staff of 10 neurosurgeons. This article traces neurosurgery at the Mayo Clinic, including several persons who contributed to its achievements over the past century.

Failure of surgical decompression for a presumed case of piriformis syndrome. Case report.

Diagnosis of piriformis syndrome is difficult and its precise definition is highly controversial. In this article, the authors present the case of a patient who had clinical features suggestive of piriformis syndrome. During surgery the patient was found to have a rare variation in anatomical structures, in which the peroneal nerve was displaced by the piriformis muscle. Surgical decompression did not alleviate the patient's symptoms.

Latrogenic snapping of the medial head of the triceps after ulnar nerve transposition.

We postulate an iatrogenic cause for snapping of the medial head of the triceps. A patient whose ulnar nerve and triceps did not dislocate over the medial epicondyle preoperatively had snapping of a portion of the medial triceps after submuscular transposition of the ulnar nerve. We believe that release of the brachial fascia and excision of the medial intermuscular septum removed the restraint to anterior translation of the medial aspect of the triceps, permitting dislocation of a portion of the medial head of the triceps with elbow flexion in this case. Previous reports of snapping of the triceps resulting after ulnar nerve transposition occurred in patients whose ulnar nerve dislocated preoperatively; in these cases, the triceps was thought to have dislocated preoperatively (along with the ulnar nerve) but was not recognized. Careful intraoperative assessment of the triceps after ulnar nerve transposition should prevent medial triceps instability as a postoperative concern.

Surgery for peripheral nerve and brachial plexus injuries or other nerve lesions.

The selection of patients who will benefit from peripheral nerve surgery continues to evolve. The evaluation of patients with peripheral nerve problems, and the indications and timing of surgery are reviewed. This includes patients with transections, lesions in continuity, entrapments, tumors, injection injuries, and birth palsies. The treatment outlined for patients with peripheral nerve and brachial plexus injuries is based on a comprehensive clinical and electrodiagnostic evaluation complemented by imaging studies. A systematic approach to the surgical management of these neural lesions has evolved at our institution, based in part on extensive experience with intraoperative recording of nerve action potentials (NAPs) and a resultant large number of referrals. Advanced microsurgical techniques including use of grafts have expanded the scope of peripheral nerve surgery. These advances coupled with intraoperative electrophysiologic measurements have improved outcomes.

Model for avulsion injury in the rat brachial plexus using passive acceleration.

We have developed an experimental model for brachial plexus injuries in the rat that closely simulates the characteristics of human injury. This model produces avulsion injuries in a noninvasive manner. A prototype apparatus was designed that allowed a force to be transmitted to a restrained limb by passive acceleration. Reproducible results were obtained in 32 rats. A significant correlation was found between the test weight and the number of roots avulsed (r = 0.92; P < 0.05). The amount of force also correlated to the pattern of avulsion injury: a 230-g weight produced either C6 (54%), C7 (15%), or C6 and C7 (31%) avulsions; a 330-g weight produced C6 (18%), C7 (9%), or C6 and C7 (73%) avulsions; a 530-g weight produced C5 through C8 (75%) or C6 through T1 (25%) avulsions. This model of brachial plexus injury may be useful to further our understanding of the cellular response to this incapacitating injury and to develop therapeutic strategies with behavioral correlates.