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Biomedical subjects

R K Simpson

Publications and source records attributed to R K Simpson.

At least 73 records · Page 4Linked to original sources
PubMed1989

Neurosurgical intervention in penetrating spinal trauma with associated visceral injury.

Associated injuries to the neck, chest, or abdomen are found in approximately one-quarter of all civilians with penetrating spinal cord or cauda equina injuries. While the value of and indications for general surgical exploration and repair of these injuries are fairly self-evident, the value of neurosurgical intervention in terms of neurological outcome and infection prophylaxis remains the subject of debate. To study this issue, 160 civilian patients with penetrating spinal injuries and neurological deficits were retrospectively reviewed. Associated injuries of the esophagus, trachea, bronchi, or bowel were seen in 107 individuals (67%); 33 (31%) of these patients had abdominal injuries, 25 (23%) had neck injuries, 23 (21%) had thoracic injuries, and 26 (24%) had injuries occurring at multiple sites. Of these 107 patients, 67 (63%) had complete neurological injuries and the remaining 40 (37%) demonstrated incomplete deficits. All 107 patients underwent surgical exploration and repair of their visceral injuries; in 19 of them a neurosurgical procedure was also performed for decompression of the neural elements and/or debridement of the wound. Regardless of the presence of associated visceral injuries, the mechanism of injury, and the extent of the neurological deficit, no statistically significant difference in neurological outcome was found in patients with or without neurosurgical intervention. Complications associated with neurological injury were reported in 17 (11%) of the total group of 160 patients. Four (21%) of the 19 patients who had neurosurgical intervention suffered a related complication, compared to only six (7%) of the 88 patients who were managed conservatively (p less than 0.05). Within the limitations of a retrospective review, the results of this study do not clearly support the value of routine neurosurgical intervention as an adjunct to general surgical repair in cases of spinal injury associated with penetrating visceral trauma.

Adolescent↗
PubMed1989

Treatment of acute penetrating injuries of the spine: a retrospective analysis.

A retrospective review of 160 cases of penetrating spinal injury (PSI) was undertaken to assess the benefits and risks of operative treatment. Criteria for operation included incomplete deficits, worsening neurological status, and associated visceral perforation. Of the 160 cases, 142 had gunshot wounds (GSW) and 18 had stab wounds (SW). Laminectomy, with or without intradural exploration, was undertaken in 23% of cases. No significant differences in outcome were found between the surgical and nonsurgical groups. Meningitis, CSF leakage, and wound infections were complications that occurred more often in the surgically treated group (22%) than the conservatively managed group (7%). It has not been possible to demonstrate a benefit of surgery in PSI in this retrospective study. A prospective study is proposed that would allow better control of the variables affecting outcome.

Acute Disease↗
PubMed1988

Coexistence of multiple arteriovenous malformations and an anomalous aortic arch.

An unusual case of multiple congenital arteriovenous malformations (AVM) coexistent with an anomalous aortic arch is described. Our patient had been asymptomatic, with physical findings limited to a low grade systolic murmur, until the onset of acute subarachnoid hemorrhage. Arteriography was technically difficult and failed to demonstrate the origin of his hemorrhage or the configuration of his aortic arch. However, an AVM within the neck muscles was visualized. Magnetic resonance imaging of his chest revealed a right-sided, retroesophageal aortic arch with an anomalous pattern of branching. The intracranial AVM and the course of the great vessels was clearly revealed at autopsy. A possible embryologic mechanism underlying the origin and distribution of the arch vasculature is discussed.

Adult↗
PubMed1988

Shotgun injuries of the spine: neurosurgical management of five cases.

The role of neurosurgical intervention in penetrating spinal injury has not been clearly established. Functional outcome has not been shown to be influenced by operation. In fact, neurosurgical intervention has been shown to potentially increase the risk of serious complications. This paper examines a unique subset of patients with penetrating spinal injury-those secondary to shotguns. An analysis of five such cases and a review of the limited literature on the subject suggests that neurosurgical intervention is of limited value in such injuries and that initial management should focus primarily upon non-neurological injuries.

Adult↗
PubMed1988

Somatosensory influence on corticomotor evoked potentials.

The clinical utility of corticomotor evoked potentials (CMEPs) as a method of evaluating and monitoring patients with spinal cord disorders is being intensively studied. Relatively few neuronal mechanisms responsible for waveform production are clearly known. Although CMEP components are dependent upon activity carried in descending motor pathways, somatosensory information can influence the basic waveform structure. By stimulating peripheral afferent fibers at varying frequencies, intensities, and trains, two CMEP component groups were identified based on latency. The configuration of the short-latency waveforms was influenced primarily by large-diameter afferents. Long-latency waveforms were altered primarily by small-diameter afferents. The present investigation describes both segmental and suprasegmental modification of CMEP characteristics based on afferent fiber group stimulation. If both motor and sensory systems can be accurately assessed, the clinical applications of CMEPs are considerably enhanced.

Animals↗
PubMed1987

Cervical diastematomyelia. Report of a case and review of a rare congenital anomaly.

Cervical diastematomyelia is a rare congenital abnormality. To our knowledge, only 18 cases have been reported. The present case was highly unusual in that it occurred in an adult. Other clinical features in the present case included symptoms that began after trauma and the presence of other associated congenital anomalies. The diastematomyelia was identified with computed tomographic metrizamide myelography and magnetic resonance imaging. The patient's neurologic deficits improved with surgery.

Adult↗
PubMed1987

Solitary brainstem metastasis: comparisons of X-ray computed tomography and magnetic resonance imaging to pathology.

A case of solitary brainstem metastasis from a bronchogenic adenocarcinoma is presented. X-ray computed tomography, magnetic resonance imaging, and specimens obtained at autopsy are compared. T2 weighted magnetic resonance images provided evidence for the diagnosis of a diffusely infiltrating process, whereas T1 weighted images demonstrated a clearly defined, well demarcated tumor. Contrast enhanced computed tomography supported evidence obtained from the T1 weighted image. At autopsy, the tumor was a well circumscribed pontine metastasis with surrounding edema. The importance of distinguishing between T1 and T2 weighted images is crucial for establishing a correct diagnosis and for instituting proper therapy. In contrast to some reports, we found that the T2 weighted image was misleading in regard to defining the extent of tumor. We conclude that both images must be considered together to provide an accurate diagnostic estimate.

Brain Neoplasms↗
PubMed1987

Late neuropathological consequences of strangulation.

A case of a young man who was a victim of strangulation is presented. He arrived at the hospital in refractory status epilepticus, controlled only with intravenous pentobarbital. The initial CT scan showed mild cortical edema. Two days later, a CT scan showed diffuse cortical swelling and bilateral basal ganglia infarcts. Upon discontinuation of pentobarbital therapy, his neurological examination revealed spontaneous ventilation and a gag reflex. A CT scan 4 weeks after the insult demonstrated hypodensities in both cerebral hemispheres and hydrocephalus. EEG was isoelectric throughout his hospitalization. He survived nearly 5 months and succumbed to pneumonia. Neuropathological examination demonstrated severe encephalomalacia, multiple cystic infarcts and generalized compensatory ventriculomegaly. Microscopic examination was particularly remarkable for a pronounced gemistocytic astrocyte proliferation in the white matter. This case illustrates the long-term neuropathological consequences of severe, global hypoxia/ischemia and the paucity of intact brain required to maintain a persistent vegetative state.

Adult↗
PubMed1987

Corticomotor evoked potentials in acute and chronic blunt spinal cord injury in the rat: correlation with neurological outcome and histological damage.

Somatosensory evoked potentials (SSEPs) and corticomotor evoked potentials (CMEPs) were utilized to study acute and chronic blunt spinal cord trauma. Rats, anesthetized with ketamine hydrochloride, were subjected to parasagittal craniectomies and midthoracic laminectomies. SSEPs were cortically recorded and CMEPs were transcortically produced using epidural ball and disc electrodes. SSEPs were elicited and CMEPs were recorded via hindlimb percutaneous needle electrodes. After control records, animals were subjected to a 50-g/cm impact to the dorsal cord surface using a modified weight drop technique. Evaluation of neurological injury was performed by SSEP and CMEP analysis and was compared with neurological assessments obtained before injury and 1 hour, 1 week, 3 weeks, and 6 weeks after injury. Neurohistopathological verification of each spinal cord lesion was performed at 6 weeks after injury. Animals subjected to a 50-g/cm cord impact showed no change in SSEP wave forms, but all components of the CMEP were greatly attenuated with this injury. Acutely, either very weak movement or no movement to noxious stimulation was present without vocalization. There was a spectrum of clinical recovery that correlated closely with the return and normalization of the amplitude of the CMEP in 100% of the animals tested. The eventual degree of clinical and CMEP improvement correlated well with the degree of histological damage present. The results of this study suggest that the CMEP is a reliable indicator of the initial degree of loss of neurological motor function in acute blunt spinal cord injury in the rat, as well as an accurate measure of the degree and extent of recovery. The rat model as outlined here is a simple and inexpensive system for evaluation both clinically and electrophysiologically of the degree of motor recovery from spinal cord injury. This model should prove useful in the evaluation of promising pharmacological agents for potential use in the treatment of acute spinal cord injury.

Acute Disease↗
PubMed1987

Corticomotor and somatosensory evoked potential evaluation of acute spinal cord injury in the rat.

Somatosensory evoked potentials (SSEPs) and corticomotor evoked potentials (CMEPs) were utilized to study acute blunt spinal cord trauma. Rats, anesthetized with ketamine hydrochloride, were subjected to a parasagittal craniotomy and a midthoracic laminectomy. SSEPs were cortically recorded and CMEPs were transcortically produced using epidural ball and disc electrodes. SSEPs were elicited and CMEPs were recorded via hindlimb percutaneous needle electrodes. After control records were made, animals were subjected to a 25-, 50-, or 75-g/cm impact to the dorsal cord surface via a modified weight drop procedure. Evaluation of neurological injury was made by SSEP and CMEP analysis as well as by physical testing with noxious stimulation applied to the hindlimb. Neurohistopathological verification of each spinal cord lesion was performed. No significant change in SSEP configuration was identified in animals subjected to a 25-g/cm cord impact; however, a small decrement in CMEP amplitude was consistently observed. Although vocalization to noxious stimulation was present, flexion activity was less than normal. Animals subjected to a 50-g/cm cord impact also showed no change in SSEP wave forms. All components of the CMEP were greatly attenuated with this injury. Either very weak movement or no movement to noxious stimulation was present without vocalization. After a 75-g/cm cord impact, both SSEPs and CMEPs were abolished. There was no movement or vocalization in response to noxious stimulation. Serial sections of the spinal cords revealed incremental destruction with increasing severity of injury. These results support the hypothesis that CMEPs are a more sensitive indicator of residual spinal cord function after injury than are SSEPs.

Afferent Pathways↗
PubMed1987

Schwannoma of the optic sheath.

An optic nerve sheath Schwannoma was surgically removed from a child. Magnetic resonance imaging was valuable for the surgical localization of the tumor. This is thought to be the first reported case of such a tumor.

Child↗
PubMed1987

Neurosurgical management of carotid sinus hypersensitivity. Report of three cases.

Carotid sinus hypersensitivity (CSH) can cause severe bradycardia, hypotension, asystole, and cardiac arrest. Three patients with the combined (mixed) cardioinhibitory and vasodepressor form of CSH were studied with intensive cardiovascular monitoring. After medical management failed, the patients were successfully treated by transection of the glossopharyngeal nerve and upper rootlets of the vagus nerve at their exit from the brain stem. Methods of diagnosis of CSH, and the benefits and limitations of medical and surgical therapies are discussed.

Autonomic Nervous System Diseases↗
PubMed1986

Nasopharyngeal carcinoma metastatic to the cauda equina.

A case of nasopharyngeal carcinoma metastatic to the cauda equina is reported. The patient, treated 3 years earlier for his primary disease, presented with bilateral weakness of his legs. Myelographic studies showed only patchy thickening of certain lumbosacral nerve roots. A biopsy from a root in the cauda equina was made through a T-12 to L-2 laminectomy revealing carcinomatous involvement. Careful examination of the specimen was necessary to distinguish the tumor from a lymphoma. Review of the literature has revealed no other cases of this type of neoplastic metastasis.

Adult↗
PubMed1986

Distal posterior cerebral artery aneurysm. Case report.

A case of an unusual distal posterior cerebral artery (PCA) aneurysm is presented. The saccular aneurysm arose from a fetal PCA distal to the posterior temporal branch of the P3 segment. The aneurysm was treated by placing a clip on the PCA distal to the anterior temporal branch of the P2 segment. A ventriculoperitoneal shunt was also placed. The patient's postoperative recovery was unremarkable and without residual neurological deficit. The highly unusual location of this aneurysm is discussed and the neurosurgical literature is reviewed in detail.

Adolescent↗