Scott C. Robertson

Idiopathic spinal epidural lipomatosis

OBJECTIVE Spinal epidural lipomatosis (SEDL) is a rare disorder often associated with the administration of exogenous steroids or the elevation of endogenous steroids. Spinal epidural lipomatosis develops in some patients in the absence of elevated steroid levels. The limited information known about idiopathic SEDL comes predominantly from isolated case reports. We proposed to study our experience with idiopathic SEDL and to review the literature. METHODS We identified eight symptomatic patients with idiopathic SEDL treated at our institution, which is the largest series reported. All patients were male and obese by body mass index (> 27.5 kg/m2). The mean age of the patients was 35.4 years. Idiopathic SEDL was equally distributed between the thoracic and lumbar spine. Six patients underwent laminectomy and fat debulking with good postoperative results; two patients were treated with a weight loss diet, which resulted in the relief of symptoms after losing > 15 kg each. RESULTS AND CONCLUSION A review of our patients in conjunction with other reported cases reveals the following: 1) idiopathic SEDL occurs almost exclusively in the obese population; 2) idiopathic SEDL seems to occur with equal frequency between the thoracic and lumber spine; 3) a strong male predominance exists; 4) thoracic SEDL presents at an earlier age compared with lumbar SEDL; 5) surgical decompression remains the treatment of choice for the immediate relief of symptoms. Our experience suggests that idiopathic epidural lipomatosis may be a pathological entity that has been underdiagnosed.

Clinical Course and Surgical Management of Massive Cerebral Infarction

OBJECTIVE:Acute occlusion of the proximal middle cerebral artery (MCA) can lead to rapid development of fatal brain swelling and ischemic strokes. Decompressive surgery, if performed early in this subpopulation of patients, can reduce mortality and result in a favorable outcome. In this article, we describe our surgical approach for treating malignant MCA syndrome and compare it with other management strategies. METHODS:This is a retrospective review of patients who developed acute occlusion of the proximal MCA and underwent aggressive surgical decompression (large craniectomy, anterior temporal lobectomy, resection of infarcted tissue, and duraplasty). The outcome of this management strategy is compared with the previously published outcomes of hemicraniectomy and dural augmentation. RESULTS:Twelve patients were included in the study. The group consisted of six men and six women (mean age, 46.8 yr). Nine patients had right MCA stroke, and three had left MCA infarction. The causes of the strokes were cardioembolic, iatrogenic, small-vessel occlusive disease, and others. The interval between infarction and clinical evidence of herniation varied from 24 hours to 10 days. Two patients died, five were independent or had moderate disabilities, and five had severe disability. CONCLUSION:Surgical decompression consisting of a large craniectomy, anterior temporal lobectomy, resection of infarcted tissue, and duraplasty is beneficial to a significant number of patients with massive MCA stroke and clinical signs of herniation.

Glycine, like glutamate, microinjected into the nucleus tractus solitarii of rat decreases arterial pressure and heart rate.

Glycinergic mechanisms have been implicated in central cardiovascular regulation. However, the inhibitory amino acids role in the nucleus tractus solitarii (NTS), the site of termination of cardiovascular afferents, has not been clarified. Thus, we sought to determine if the microinjection of glycine into the NTS alters arterial pressure and heart rate. Microinjections of glycine, like glutamate, confined to the NTS decreased arterial pressure and heart rate in a neurally mediated, dose-dependent manner. The glycine antagonist strychnine completely blocked these effects of glycine but did not itself alter arterial pressure or heart rate, or interfere with the baroreceptor reflex. The acute hypotensive, bradycardic response to glycine was followed by a period during which glycine essentially eliminated the cardiovascular responses to the microinjection into the NTS of glutamate, an amino acid reputed to be a transmitter in the baroreceptor reflex arc. These data suggest that glycine is involved in cardiovascular regulation by the NTS but do not support its being an integral transmitter in the baroreceptor reflex.

Hemorrhagic Complications in Association with Silastic Dural Substitute: Pediatric and Adult Case Reports with a Review of the Literature

OBJECTIVE AND IMPORTANCE Delayed intracranial hemorrhage is an unusual complication associated with the use of silastic dural substitute. CLINICAL PRESENTATION We present three patients with this complication. Two adult patients developed subdural and epidural hemorrhages 9 months and 10 years after posterior fossa surgery for Chiari malformations. The remaining patient, a 13-month-old child, is the youngest reported patient to develop an epidural hematoma 8 months after a craniosynostosis repair. INTERVENTION The hematomas were removed with the silastic dural substitute from all three patients, and the dural defect was repaired with autologous paracervical fascia. CONCLUSION Silastic dural grafts have an increased incidence of hemorrhage associated with their use. A slight increase in the prevalence of hemorrhagic complications with silastic dural substitute was observed in women. We report our radiographic and surgical findings, including an extensive review of the literature.

Occipital Calvarial Bone Graft in Posterior Occipitocervical Fusion

Study Design. Dorsal occipitocervical fusion is associated with a high rate of fusion failure and requires an additional surgical site for donor bone graft harvesting. In this series, an autologous occipital calvarial bone graft obtained from the same occipitocervical incision with contoured metal loops was used in 25 adults to achieve craniovertebral stabilization and fusion. Objectives. To study the use of autologous occipital calvarial bone grafts in occipitocervical fusion. Summary of Background Data. Cranial bone grafts have been used successfully in craniofacial reconstruction with good long‐term results. In the plastic surgery literature, there are claims that membranous bone grafts are superior to endochondral bone grafts in fusions because of decreased resorption. In recent studies, results have shown successful use of calvarial bone in fusing the upper cervical spine in children. The use of autologous occipital bone in posterior occipitocervical fusions avoids many of the problems associated with traditional donor sites and provides a sufficient quantity of good quality bone for the fusion. This is especially true in the fragile rheumatoid arthritis patient with cranial cervical instability. Method. Split‐thickness, autologous calvarial bone grafts with contoured loop and cable instrumentation were used for posterior occipitocervical stabilization and fusion in 25 patients, most of whom had rheumatoid arthritis. The calvarial bone graft was harvested from the occipital skull, using a microair impactor, and was secured next to the loop construct. After surgery, all patients were immobilized with external orthoses. Results. None of the patients had hardware failure or complications from the occipital graft procurement. In 22 patients, good alignment, stability, and bony fusion were shown on radiographs. Conclusions. Occipital calvarial bone graft appears to work as well as other autologous corticocancellous bone grafts routinely used in posterior occipitocervical fusions.

Nucleus prepositus hypoglossi. A medullary pressor region.

Electrical stimulation of fibers of passage through the fastigial nucleus increases arterial pressure. To identify nuclei that may project through the pressor region of the fastigial nucleus, we injected the retrograde tracer fast blue unilaterally at confirmed pressor sites in the nucleus. In seven rats, we found dense fluorescent labeling bilaterally in the external cuneate, lateral reticular, medial vestibular, and caudal prepositus hypoglossi nuclei, and contralaterally in the inferior olivary nucleus. There had been no reports of a cardiovascular role for the nucleus prepositus hypoglossi; thus, we sought to determine if electrical or chemical stimulation of that nucleus or the adjacent medial vestibular nucleus altered arterial pressure or heart rate in 24 anesthetized rats. Both types of stimuli to the caudal, but not the rostral, pole of the nucleus prepositus hypoglossi or to the medial vestibular nucleus elicited an increase in arterial pressure; bradycardia accompanied the former and tachycardia the latter. Both the nucleus prepositus hypoglossi and medial vestibular nucleus may participate in central cardiovascular regulation.

Increased Height in Patients with Medulloblastomas

OBJECTIVE Medulloblastomas demonstrate histological features similar to neuroendocrine tumors. Expression of various receptors for growth factors and production of growth hormones have been identified to occur with medulloblastomas. We studied the preoperative height of patients with medulloblastomas. METHODS We studied 85 patients (64 children and 21 adults) with medulloblastomas and 42 patients (27 children and 15 adults) with cerebellar astrocytomas who served as a control group. All of the patients had their height and weight documented on standardized growth charts. In addition, age, sex, symptoms, radiographic findings, treatment, and survival were examined. RESULTS Preoperatively, 22.4% of the patients with medulloblastomas were above the 95% curve in height and 80.0% were above the 50% curve for height. Compared with patients with cerebellar astrocytomas, 7.1% were above the 95% curve for height and 54.8% were above the 50% curve for height. The distribution of patients along the weight curves for both tumor types demonstrated a slight prevalence for lower weights but was not significantly different from the national average. A significant number of patients presenting with medulloblastomas attained increased height, which was disproportionate to the weight loss generally observed with neoplasms. To our knowledge, the disproportionate number of patients with medulloblastomas and increased height has not been reported before. A similar deviation in height distribution from the normal population could not be identified in patients with cerebellar astrocytomas. CONCLUSION This study suggests that medulloblastomas may be influenced by growth hormone production or may produce growth factors in vivo.