Pin-site myiasis: a rare complication of halo orthosis.

STUDY DESIGN: Case report. OBJECTIVE: To report a rare complication following halo placement for cervical fracture. SETTING: United States University Teaching Hospital. CASE REPORT: A 39-year-old woman who sustained a spinal cord injury from a C6-7 fracture underwent halo placement. She subsequently developed an infection adjacent to the right posterior pin, which then became infected with Diptera larvae (maggots), necessitating removal of the pin and debridement of the wound site. CONCLUSION: Halo orthosis continues to be an effective means of immobilizing the cervical spine. Incidence of complications ranges from 6.4 to 36.0% of cases. Commonly reported complications include pin-site infection, pin penetration, pin loosening, pressure sores, nerve injury, bleeding, and head ring migration. Pin-site myiasis is rare, with no known reports found in the literature. Poor pin-site care by the patient and her failure to keep follow-up appointments after development of the initial infection likely contributed to the development of this complication.

Persistent autoregulatory disturbance after angioplasty for cerebral vasospasm. A case report.

SUMMARY: Hyperdynamic therapy, consisting of hypervolemia, haemodilution, and hypertension, is an established treatment for cerebral vasospasm following subarachnoid haemorrhage. Angioplasty has emerged as an additional, effective treatment for symptomatic vasospasm. Loss of autoregulation, however, can occur despite effective angioplasty, underscoring the need for treatment with hyperdynamic therapy in combination with angioplasty. A 43-year-old woman underwent endovascular coiling of a ruptured left posterior communicating artery aneurysm. The patient went on to develop symptomatic vasospasm and was treated with hyperdynamic therapy and angioplasty. Autoregulation was assessed with xenon CT cerebral blood flow (CBF) measurement. An initial CBF study was obtained when the patient received dopamine and dobutamine infusions to maintain systolic blood pressure at 160 mmHg. The vasopressor drips were then temporarily held for twenty minutes, allowing the patient's systolic blood pressure to drop to 140 mmHg, and a repeat CBF study was obtained. Several days after angioplasty, CBF decreased significantly when the patient was taken off vasopressors, indicating impaired autoregulation. Hyperdynamic therapy was continued, and another CBF study one week later showed a return of autoregulation and normalization of CBF without induced hypertension. Autoregulation is disturbed during vasospasm. Although angioplasty can improve large artery blood flow during vasospasm, hyperdynamic therapy is also needed to maintain cerebral perfusion, particularly in the face of impaired autoregulation. Quantitative CBF measurement permits the maintenance of optimal CBF and monitoring of response to therapy.

Stereotactic navigation for placement of pedicle screws in the thoracic spine.

OBJECTIVE: Pedicle screw fixation in the lumbar spine has become the standard of care for various causes of spinal instability. However, because of the smaller size and more complex morphology of the thoracic pedicle, screw placement in the thoracic spine can be extremely challenging. In several published series, cortical violations have been reported in up to 50% of screws placed with standard fluoroscopic techniques. The goal of this study is to evaluate the accuracy of thoracic pedicle screw placement by use of image-guided techniques. METHODS: During the past 4 years, 266 image-guided thoracic pedicle screws were placed in 65 patients at the University of Michigan Medical Center. Postoperative thin-cut computed tomographic scans were obtained in 52 of these patients who were available to enroll in the study. An impartial neuroradiologist evaluated 224 screws by use of a standardized grading scheme. All levels of the thoracic spine were included in the study. RESULTS: Chart review revealed no incidence of neurological, cardiovascular, or pulmonary injury. Of the 224 screws reviewed, there were 19 cortical violations (8.5%). Eleven (4.9%) were Grade II (< or =2 mm), and eight (3.6%) were Grade III (>2 mm) violations. Only five screws (2.2%), however, were thought to exhibit unintentional, structurally significant violations. Statistical analysis revealed a significantly higher rate of cortical perforation in the midthoracic spine (T4-T8, 16.7%; T1-T4, 8.8%; and T9-T12, 5.6%). CONCLUSION: The low rate of cortical perforations (8.5%) and structurally significant violations (2.2%) in this retrospective series compares favorably with previously published results that used anatomic landmarks and intraoperative fluoroscopy. This study provides further evidence that stereotactic placement of pedicle screws can be performed safely and effectively at all levels of the thoracic spine.

Metastatic adenocarcinoma to the brain mimicking hemorrhage: case report.

BACKGROUND: Computerized tomography (CT) of metastatic adenocarcinoma to the brain usually shows low-to-moderate attenuation. However, mucinous adenomas may appear with high attenuation, mimicking hemorrhage. CASE DESCRIPTION: A 68-year-old man with a history of metastatic esophageal adenocarcinoma presented to the emergency room complaining of a chronic, progressive right occipital headache. A head CT demonstrated a moderate-to-high attenuation, homogenous mass in the right cerebellar hemisphere consistent with an intracerebral hemorrhage. There was no frank calcification in the mass by CT criteria. An emergent posterior fossa craniectomy revealed nonhemorrhagic metastatic mucinous adenocarcinoma. CONCLUSION: Moderate-to-high attenuation, noncalcified brain masses should raise the possibility of mucin-containing neoplasm.

Prospective randomized comparison of the Shouldice and Lichtenstein hernia repair procedures.

OBJECTIVE: To compare the Lichtenstein, tension-free mesh, and the Shouldice, 4-layer Bassini repair of the inguinal hernia. DESIGN: Prospective randomized clinical trial. SETTING: A private suburban hernia center. PATIENTS: Six hundred seventy-two men with inguinal hernias, aged 20 to 90 years, seen at the hernia center between January 1, 1990, and December 31, 1995. INTERVENTIONS: Slightly modified Shouldice and Lichtenstein repairs were used to repair primary and recurrent inguinal hernias. MAIN OUTCOME MEASURES: Recurrence rates, symptoms (including patient satisfaction), and infections. RESULTS: A total of 717 repairs in 672 patients, including 45 bilateral repairs, have been monitored to date. Recurrence of hernia occurred in 7 Shouldice repairs and 2 mesh repairs. Twelve superficial infections associated with Shouldice and 6 associated with mesh repairs were found. CONCLUSIONS: Both types of hernia repair are comparable and effective, but long-term results favor the Lichtenstein technique for reducing recurrences (to a P value of .10), ease of technical mastery, and application to the outpatient setting by use of a local anesthetic.

Computer-assisted measurement of lumbar spine radiographs.

RATIONALE AND OBJECTIVES: The authors evaluated a method for obtaining reproducible, reliable measurements from standard lumbar spine radiographs for determining the degree of spondylolisthesis, vertebral body height, intervertebral disk space height, disk space angle, and degree of vertebral body wedging. MATERIALS AND METHODS: Four to six easily defined points were identified on each vertebral body on anteroposterior and lateral plain radiographs of the lumbosacral spine of patients. From these points, the degree of spondylolisthesis, the vertebral body height, the intervertebral disk space height, the disk space angle, and the degree of vertebral body wedging were easily calculated by using well-known geometric relationships. This method requires the use of a personal computer and a standard spreadsheet program but does not require the use of any other specialized radiographic equipment, computer hardware, or custom software. RESULTS: Calculations of intra- and interobserver variability for the measurement of spondylolisthesis, disk space height, disk space angle, and vertebral body height measurement showed that the technique is extremely reproducible. CONCLUSION: This technique may prove useful in the prospective evaluation of potential candidates for lumbar spinal stenosis surgery.

CT-guided brachial plexus biopsy.

We describe a technique for conducting a CT-guided biopsy of the brachial plexus region, report two illustrative cases, discuss potential complications, and conclude that, in selected cases, biopsy of lesions in the region of the brachial plexus can be performed safely with CT guidance.

Outcome after laminectomy for lumbar spinal stenosis. Part I: Clinical correlations.

All patients who underwent decompressive lumbar laminectomy in the Washtenaw County, Michigan metropolitan area during a 7-year period were studied for the purpose of defining long-term outcome, clinical correlations, and the need for subsequent fusion. Outcome was determined by questionnaire and physical examination from a cohort of 119 patients with an average follow-up evaluation interval of 4.6 years. Patients graded their outcome as much improved (37%), somewhat improved (29%), unchanged (17%), somewhat worse (5%), and much worse (12%) compared to their condition before surgery. Poor outcome correlated with the need for additional surgery, but there were few additional significant correlations. No patient had a lumbar fusion during the study interval. The outcome after laminectomy was found to be less favorable than previously reported, based on a patient questionnaire administered to an unbiased patient population. Further randomized, controlled trials are therefore necessary to determine the efficacy of lumbar fusion as an adjunct to decompressive lumbar laminectomy.

Outcome after laminectomy for lumbar spinal stenosis. Part II: Radiographic changes and clinical correlations.

The pre- and postoperative lumbar spine radiographs of 119 patients who underwent decompressive lumbar laminectomy were studied to evaluate radiographic changes and to correlate them with clinical outcome. An accurate and reproducible method was used for measuring pre- and postoperative radiographs that were separated by an average interval of 4.6 years. Levels of the spine that underwent laminectomy showed greater change in spondylolisthesis, disc space angle, and disc space height than unoperated levels. Outcome correlated with radiographic changes at operated and unoperated levels. This study demonstrates that radiographic changes are greater at operated than at unoperated levels and that some postoperative symptoms do correlate with these changes. Lumbar fusion should be considered in some patients who undergo decompressive laminectomy. The efficacy of and unequivocal indications for lumbar fusion can only be determined from randomized, prospective, controlled trials, however, and these studies have not yet been undertaken.

Meningeal metastasis of the cerebellopontine angle demonstrating "dural tail" sign.

Local leptomeningeal enhancement adjacent to a dural-based mass, observed in magnetic resonance images, has been called a "dural tail" and was initially considered a sign specific for meningioma. Recent work has shown that the dural tail (or "flare") sign may also be seen in association with other dural-based lesions. The authors present a case of a dural-based mass in the cerebellopontine angle that had a dural tail; at surgery, the mass proved to be a metastatic lesion. The authors stress that the dural tail sign is not specific for meningioma or neoplastic invasion; it sometimes simply reflects reactive changes. Furthermore, it is not even specific for dural-based masses, as it may be seen in association with both intra-axial and extra-axial lesions.

Development of neurosurgery at the University of Michigan.

The University of Michigan Medical School was founded in 1847, 30 years after the university itself. The first hospital in Ann Arbor was a 20-bed unit converted from a private house, that admitted only charity patients. The second University Hospital was built in 1925. The Section of Neurosurgery was founded by Dr. Max Peet, who was followed by Drs. Kahn and Schneider as section heads.

Selective culture of mitotically active human Schwann cells from adult sural nerves.

We devised a simple method to isolate mitotically active human Schwann cells from sural nerve biopsy specimens and expand the population in culture. Nerve fascicles were treated with cholera toxin for 7 days in culture before dissociation, which increased the cell yield at least twenty-five-fold over immediated tissue dissociation. Digesting the tissue completely with enzymes in serum-containing medium resulted in the highest cell viability, and released 2 to 6 x 10(4) cells/mg of tissue. Seeding the cells on a poly-L-lysine substrate in a small volume of serum-free medium optimized the plating efficiency. Although Schwann cells comprised 90% of the initial culture population, their numbers declined over time due to a faster mitotic rate of the fibroblasts in the presence of cholera toxin alone. However, treating the cultures with a combination of cholera toxin and forskolin, which act synergistically to elevate cyclic AMP levels, inhibited fibroblast growth without causing Schwann cell toxicity. Adding glial growth factor to the adenyl cyclase activators maximized Schwann cell proliferation, and the population rapidly and selectively expanded. Therefore, it should be possible to generate large numbers of Schwann cells from diseased nerves to study defects in cell function or from normal nerves to study the effects of Schwann cell grafts on neuronal regeneration.

Ligamentum flavum hematoma. Report of two cases.

Two patients presenting with signs and symptoms suggestive of nerve root compression secondary to extradural masses were found to have ligamentum flavum hematomas. Both patients had neurological deficits preoperatively and regained normal function postoperatively. There was no significant antecedent injury in either case. The symptom course was longer than that for spontaneous epidural hematoma. In one case, there was remodeling of bone, initially suggesting either infection or tumor.

Pre- and post-operative cerebral blood flow changes in subarachnoid haemorrhage.

Assessment of cerebral perfusion on patients with subarachnoid haemorrhage (SAH) in the Neurologic Intensive Care Unit is difficult since nuclear medicine imaging modalities capable of measuring cerebral blood flow (CBF) are not generally available. We performed 101 quantitative (ml 100g-min) bedside CBF measurements on 40 individual patients to correlate SAH grade with CBF and to assess the effect of surgical intervention on CBF. Global CBF (G-CBF) and bihemispheric CBF (B-CBF) asymmetry were correlated with the grade of SAH pre- and post-operatively. Data analysis showed that pre-operative patients with low grade SAH (Hunt and Hess grades 0 to 2) had higher mean G-CBF values [44.2 +/- 71] than those with high grade SAH (Hunt and Hess grades 3 to 4): [mean G-CBF = 34.1 +/- 1.7]. Post-surgery there was a significant improvement in G-CBF; CBF increased [5.3 +/- 1.07] in the group of patients with low grade SAH. Patients with high grade SAH showed no significant improvement in their G-CBF during the first week post-operatively compared to pre-operative values. We conclude that portable units capable of measuring bedside CBF values are useful in monitoring CBF changes in patients with SAH. Patients with low grade SAH have G-CBF within normal limits both pre-operatively and post-operatively, with a statistically significant increase in CBF during two weeks post-operatively. Patients with high grade SAH show no significant increase in CBF one week post-operatively compared to their pre-operative measures.

Clinical decision making in brachial plexus injuries.

In the not too distant past brachial plexus injuries were considered to have a poor, almost hopeless, prognosis, and a conservative approach of waiting for any spontaneous recovery was advocated. The development of microtechniques for nerve grafting and repair combined with precise electrophysiologic testing of nerve continuity by SSEP and NAP techniques have changed this outlook completely. An aggressive approach to plexus injuries can now be advocated. This approach must be grounded in a thorough knowledge of the internal and external anatomy of the plexus and a careful analysis of each injured element. The type, location, and degree of injury to each area of the plexus are the critical factors in determining the proper course of action in these injuries. Organization of these data, derived from serial clinical and electrical examinations, provides the framework for clinical decisions in brachial plexus injuries. Classification of the many aspects of a plexus injury will simplify the decision making in what may initially seem to be a hopelessly complicated problem.

Unusual cause of 'piriformis muscle syndrome'.

The piriformis muscle syndrome is a controversial "clinical" syndrome primarily characterized by signs and symptoms of sciatic nerve compression at the region of the piriformis muscle as it passes through the greater sciatic notch. The syndrome is often referred to; however, cases are rarely reported, and it is generally an uncommon diagnosis. Of those cases reported, the incidence is six times more frequent in females than in males, and is typically temporally related to minor pelvic or buttock trauma. We describe a case of a 40-year-old woman presenting with signs and symptoms suggestive of piriformis muscle syndrome following a gynecologic procedure performed in the dorsal lithotomy position. Electromyographic findings were consistent with this clinical entity. Operative exploration, however, revealed the source of neural compression to be a pseudoaneurysm of the inferior gluteal artery adjacent to the piriformis muscle. The diagnostic features of this clinical syndrome are discussed.

Giant sacrolumbar meningioma. Case report.

A case of giant sacral meningioma with presacral and lumbar extension is presented. The difficulties in diagnosis and management are emphasized including the staged multidisciplinary surgical approaches and preoperative tumor embolization.

Management of anteriorly located C1-C2 neurofibromata.

The authors discuss their recent experience with anteriorly located C1-C2 neurofibromata in five patients with cervical myelopathy and magnetic resonance scans consistent with intradural extramedullary masses in this region. Surgery was performed using a posterolateral approach with microscopic intradural exploration. Gross total intradural tumor removal was achieved in all cases. Improvement in cervical myelopathy occurred in all patients. This report concludes that C1-C2 neurofibromata located anterior to the spinal cord can be totally and safely removed using a posterolateral approach. Improvement in neurologic dysfunction accompanies posterior decompression and gross total intradural tumor removal.

Sacral and presacral tumors: problems in diagnosis and management.

We reviewed 9 cases of sacral tumors with presacral extension. These included 2 chordomas, 1 metastatic renal cell carcinoma, 2 schwannomas (1 malignant, 1 benign), 1 neurofibroma, 1 neurofibrosarcoma, 1 aneurysmal bone cyst, and an exceedingly rare meningioma. The sex of the patients was not significant. The age of the patients at diagnosis ranged from 13 to 68 years (mean, 47 years). Initial symptoms of low back and radiating leg pain were present in all but 1 patient. The duration of symptoms prior to diagnosis ranged from 1 month to 9 years (mean, 2.6 years). A delay in diagnosis of 2 years or more occurred in 6 of the 9 patients. Progressive perineal numbness and/or sphincter dysfunction were seen in 6 patients, and a palpable rectal mass was noted in 6 of 9 patients. The efficacy of various diagnostic tests is presented, as are the surgical options--needle biopsy and anterior and posterior approaches. Despite improved radiographic imaging techniques, these unusual tumors are often diagnosed at an advanced stage, and may masquerade as discogenic radiculopathy. Late diagnosis contributes to the difficulty of surgical extirpation. Anterior and posterior surgical approaches involving general, orthopedic, and urological surgeons may be required.

A simple device for controlling suction force in neurosurgical operations.

A simple and inexpensive device for controlling suction force in neurosurgical operations is described. This device is interposed in the suction tubing on the sterile surgical field. This has the advantage of allowing the surgeon to alter the suction force quickly and easily, according to his or her preference. The total cost is minimal, and the device may be assembled with supplies currently available in most operating rooms.