PubMed Health⌕ Search

Biomedical subjects

H L Harkey

Publications and source records attributed to H L Harkey.

At least 19 recordsLinked to original sources
PubMed2000

Spinal cord injury in Mississippi. Findings and evaluation, 1992-1994.

STUDY DESIGN: The Mississippi spinal cord injury surveillance system is both active and passive, designed to capture all cases of spinal cord injury through mandated reporting by multiple sources. Each case is confirmed by medical record review. OBJECTIVES: To describe the development of a state-wide spinal cord injury surveillance system, discuss findings from the system, and evaluate sensitivity. SUMMARY OF BACKGROUND DATA: In the United States, the annual incidence rate of spinal cord injury requiring hospital admission has been estimated at 32-50 per million. With prehospital fatalities included, the estimated incidence rate ranges from 43 to 55 per million population annually. METHODS: In the current study all cases identified during the first 2 years of operation of the spinal cord injury (SCI) system were included. To evaluate the sensitivity of the system, International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) codes from each hospital's discharge database were used. RESULTS: The incidence rate among patients in hospitals and prehospital fatal cases was 77 per million. The rate for patients in hospitals was 59 per million. The incidence rate of spinal cord injury among males was 4.4 times higher than among females. Rates of spinal cord injury were highest among persons 20-24 years of age. Rates were similar for whites and blacks. The most frequent causes of spinal cord injury were motor vehicle collisions, violence, and falls. Additional cases were identified during the evaluation, resulting in a 94% sensitivity. CONCLUSIONS: Mississippi's spinal cord injury incidence rates are substantially higher than rates reported for other states except Alaska. The surveillance system was found to be very complete. Prevention efforts should focus on increasing safety belt usage, increasing alcohol awareness, and reducing violence.

Adolescent↗
PubMed1999

Morphological changes after percutaneous transluminal angioplasty.

BACKGROUND: Percutaneous transluminal angioplasty (PTA) dilates constricted arteries at the circle of Willis to reverse cerebral ischemia caused by cerebral vasospasm. Although 90% of the patients show angiographic improvement after PTA, only 70% show clinical improvement. Why some patients do not improve after PTA is unknown. We report on a 48-year-old woman who failed to improve after PTA and died from aneurysm rerupture. Pathologic studies were performed to determine why PTA failed to reverse the symptoms of cerebral ischemia. METHODS: The arteries of the brain were studied by light microscopy using Gomori's trichrome stain. The arteries were also studied by scanning and transmission electron microscopy. RESULTS: The arteries that were dilated with PTA showed compression of the connective tissue, stretching of the internal elastic lamina, and a combination of compression and stretching of the smooth muscle. The small arteries and arterioles that had been treated with an infusion of intraarterial papaverine were constricted with a thickened intimal layer. CONCLUSION: The persistence of cerebral vasospasm in small and perforating arteries may contribute to the failure of cerebral ischemia to reverse after PTA.

Angioplasty, Balloon↗
PubMed1999

Hemangioblastoma of the filum terminale: case report.

OBJECTIVE AND IMPORTANCE: Tumors of the cauda equina and specifically the filum terminale are uncommon. We report the fourth case of a hemangioblastoma occurring in the filum terminale. CLINICAL PRESENTATION: This 35-year-old man presented with a 4-year history of low back pain that had been previously diagnosed as a bulging disc and exhibited severe pain in response to percussion of his lower back but was neurologically intact. He was found to have a large, enhancing mass filling the thecal sac at L2-L3. INTERVENTION: The tumor was found to be attached to the filum terminale and was cleanly dissected off en toto. Microscopically, the mass consisted of endothelial cells in addition to abundant fat-laden stromal cells and reticulum. CONCLUSION: We present a case report and a review of the literature. Our patient was the first to exhibit no radicular complaints. The diagnosis was delayed in all four cases and was not determined until the time of surgery. Complete excision offers the best chance for cure, and spinal angiography can aid in diagnosis. However, a high index of suspicion is needed for preoperative detection.

Adult↗
PubMed1998

Spinal cord injury incidence in Mississippi: a capture-recapture approach.

BACKGROUND: Many studies have investigated spinal cord injury incidence rates. Few, however, have adjusted for the underascertainment. The current study used the capture-recapture method to estimate the ascertainment-corrected spinal cord injury incidence rate in Mississippi. METHODS: Two sources were used for case ascertainment: Mississippi's spinal cord injury registry and hospital reports. The two-sample capture-recapture method was used to adjust for undercount. RESULTS: Two hundred one spinal cord injuries were reported to or found by the Mississippi State Department of Health in 1993, with a crude incidence rate of 7.8 per 100,000 population per year among hospital admissions and prehospital fatalities. Using the two-sample capture-recapture method, it is estimated that the incidence rate would be 9.3 per 100,000 population per year. CONCLUSION: Capture-recapture estimates suggest that Mississippi's spinal cord injury incidence rate is more than twice the national average.

Epidemiologic Methods↗
PubMed1996

Behavior of the H-reflex in humans following mechanical perturbation or injury to rostral spinal cord.

In humans H-reflexes are suppressed during early spinal shock. In animals rostral cord injury results in loss of segmental reflexes within seconds. If H-reflexes persist under general anesthesia, can they be used to monitor the integrity of the rostral cord? In part I of this study, we recorded H-reflexes intraoperatively in 25 patients to elucidate general anesthesia effect. In 23 subjects, H-reflexes were consistently elicited, and within +/- 13% of the normalized group mean amplitude. In part II, we recorded H-reflexes in 31 patients during spinal cord surgery to elucidate H-reflex behavior immediately following rostral spinal cord injury. In 6, abrupt suppression of the H-reflex coincided with cord injury. In 4 of 6, suppression was transient and less than 50% of baseline; none of these patients developed neurological deficits. In 2, suppression exceeded 90% and persisted throughout surgery; both patients developed profound deficits. We conclude that (1) the H-reflex can be consistently elicited under general anesthesia in most patients, (2) rostral cord injury rapidly suppresses the H-reflex, and (3) the degree and duration of H-reflex suppression reflects the severity of the injury.

Adolescent↗
PubMed1995

Primary treatment of unstable Jefferson's fractures.

The Magerl transfacet screw technique is a method of fixation for unstable burst fractures of the atlas (Jefferson's fracture) that precludes the use of a halo brace or stabilization from the occiput to C2. Two cases are presented utilizing this mode of treatment to obtain solid arthrodesis and maintain intact motion at occipital cervical junction. No increased displacement of the fractured ring of C1 occurred with the screw insertion. Thus, primary C1-C2 transfacet screw fixation is a useful alternative treatment for unstable Jefferson's fractures.

Adult↗
PubMed1995

Experimental chronic compressive cervical myelopathy: effects of decompression.

Twelve dogs developed a delayed onset of neurological abnormalities from chronic cervical cord compression that was characteristic of myelopathy. The animals were divided into two groups and matched according to degree of neurological deficit. Six animals underwent decompression through removal of the anteriorly placed compressive device. Throughout the experiment, serial neurological examinations and somatosensory evoked potential studies were performed on each animal. Spinal cord blood flow measurements were obtained during each surgical procedure and at sacrifice. Magnetic resonance images were obtained after compression and before sacrifice. All animals in the decompressed group showed significant neurological improvement after decompression; no spontaneous improvement in neurological function was seen in the compressed group. On pathological examination, irreversible changes including large motor neuron loss, necrosis, and cavitation were seen in four of the animals in the decompressed group and five in the compressed group. Cervical spondylotic myelopathy in humans is known to respond to decompression; this study provides further evidence that this animal model for chronic compressive cervical myelopathy accurately reflects the disease process seen in humans.

Animals↗
PubMed1994

Nystagmus and joint position sensation: their importance in posterior occipitocervical fusion in rheumatoid arthritis.

It is widely believed that brain stem dysfunction and cranial nerve palsies in patients with rheumatoid arthritis (RA) are common and related to the vertical translocation of the odontoid process. In our database of 235 patients with seropositive RA and craniocervical junction involvement, we have found a very low incidence of such problems. Long tract signs were common, but loss of proprioception (joint position sensation) as the sole neurologic deficit was rare. Nystagmus was found to be associated with the tonsillar herniation of a Chiari 1 malformation and loss of joint position sensation with severe compression of the posterior aspect of the spinal cord at the craniocervical junction. The implications for posterior occipitocervical fusion, particularly by sublaminar wiring, are discussed.

Adolescent↗
PubMed1994

Precise and limited decompression for lumbar spinal stenosis.

Fifty-eight consecutive patients with lumbosacral nerve root entrapment due to spinal stenosis were treated with modified microsurgical decompression. Only the clinically relevant sides and levels were decompressed while the spinous processes, the interspinous ligaments, the medial portion of ligamentum flavum and the functionally important parts of the facet joints were preserved. The reviewers rated recovery as good or excellent in 71% of patients while patient self-assessment indicated 76% good or excellent outcome. These data suggest that microsurgical decompression of spondyloarthritic changes can effectively relieve the signs and symptoms of nerve root compression and that with careful evaluation of all available data the number of nerve roots requiring decompression is often fewer than what is suggested by diagnostic images alone.

Adult↗
PubMed1994

Severe cervical kyphotic deformities in patients with plexiform neurofibromas: case report.

Two patients with cervical plexiform neurofibromas are presented. Each of these patients had severe cervical kyphosis and has undergone anterior decompression, anterior reconstruction, and posterior stabilization. We discuss the surgical management of cervical kyphotic deformities associated with plexiform neurofibromas and review the factors associated with bony changes in neurofibromatosis.

Adolescent↗
PubMed1993

Infiltrative clival pituitary adenoma of ectopic origin.

An ectopic pituitary adenoma is a rare entity that may occur in several anatomic locations, the sphenoid sinus being the most common. Many of these tumors are amenable to surgical resection by means of a transsphenoidal approach. A more aggressive surgical approach is needed to attempt resection of extensive tumors that involve the clivus and the nasopharynx. Complete resection in these areas cannot always be guaranteed or determined, necessitating postoperative radiotherapy. Many different tumors of the sphenoid sinus and skull base can resemble ectopic pituitary adenomas on radiologic assessments. Because of this, preoperative endocrine assessment is recommended.

Adenoma↗
PubMed1993

The "subdural" space: a new look at an outdated concept.

This review considers the structure of the meninges, as seen at the electron microscopic level, with particular emphasis on the dura-arachnoid junction and whether a naturally occurring space is found at this interface. The classic view has been that a so-called subdural space is located between the arachnoid and dura and that subdural hematomas or hygromas are the result of blood or cerebrospinal fluid accumulating in this (preexisting) space. The dura is composed of elongated, flattened fibroblasts and copious amounts of extracellular collagen. A specialized layer of fibroblasts, the dural border cell layer, is found at the dura-arachnoid junction and is characterized by flattened fibroblasts, no extracellular collagen, extracellular spaces, and few cell junctions. These features combine to create a layer of the inner dura that is structurally weak when compared with external portions of the dura and the internally located arachnoid. The arachnoid layer is composed of larger cells with numerous cell junctions, no extracellular space, and no extracellular collagen. The occurrence of many tight junctions in this layer also serves as a barrier to the movement of fluids and ions. Fibroblasts specialized to form the arachnoid trabeculae attach to the inner surface of the arachnoid layer, bridge the subarachnoid space, and surround vessels in the subarachnoid space as well as attach to pia on the surface of the brain. Under normal conditions, there is no evidence of a naturally occurring space being extant at the dura-arachnoid junction. A space may appear at this point subsequent to pathological/traumatic processes that result in tissue damage with a cleaving opening of the structurally weakest plane in the meninges--through the dural border cell layer. Furthermore, when a space does appear, it is not "subdural" in location but rather within a morphologically distinct cell layer.

Animals↗
PubMed1993

Experimental chronic compressive cervical myelopathy.

A canine model simulating both cervical spondylosis and its results in delayed progressive myelopathy is presented. This model allowed control of compression, an ongoing assessment of neurological deficits, and evaluation using diagnostic images, frequent electrophysiological tests, local blood flow measurements, and postmortem histological examinations. Subclinical cervical cord compression was achieved in 14 dogs by placing a Teflon washer posteriorly and a Teflon screw anteriorly, producing an average of 29% stenosis of the spinal canal. Four dogs undergoing sham operations were designated as controls. Twelve of the animals undergoing compression developed delayed and progressive clinical signs of myelopathy, with a mean latent period to onset of myelopathy of 7 months. Spinal cord blood flow studies using the hydrogen clearance method showed a significant transient increase in blood flow immediately after compression and a decrease before sacrifice. Somatosensory evoked potential studies indicated progressive deterioration during the period of compression. Magnetic resonance images revealed intramedullary changes. Histological studies showed abnormalities overwhelmingly within the gray matter, including changes in vascular morphology, loss of large motor neurons, necrosis, and cavitation. Axonal degeneration and obvious demyelination were rarely seen. The most profound morphological changes occurred at the site of greatest compression. It is proposed that a momentary arrest of microcirculation occurs during extension of the neck because of loss of the reserve space in the compromised spinal canal. This microcirculatory disturbance is predominant in the watershed area of the cord and mainly affects the highly vulnerable anterior horn cells, leading to neuronal death, necrosis, and eventual cavitation at the junction of the dorsal and anterior horns. Additional supportive evidence of this hypothesis was derived from the literature.

Angiography↗
PubMed1992

Lateral cervical spine dislocation and vertebral artery injury.

Although anterior and posterior traumatic displacement of cervical vertebrae are commonly noted, and the devastating neurological deficits associated with these injuries have been amply defined, lateral displacement with fractures has been rarely recognized, and the clinical significance of this injury has been overlooked. This report describes five cases of cervical spine fractures with lateral dislocation. All patients had lateral and anteroposterior cervical spine radiographs as well as cervical angiography or postmortem study demonstrating either complete occlusion or significant impairment of flow of the vertebral arteries. Two cases had traumatic vertebral artery occlusion with secondary medullary and cerebellar infarction resulting in the patient's death. Vertebral artery injury apparently is not uncommon in this particular type of fracture. The diagnosis of these vascular injuries may require angiography or magnetic resonance angiography. A vertebral occlusion or dissection is a problem of considerable complexity, requiring individualized management depending on the patient's symptomatology, location and nature of the injury, and time lapsed since the injury.

Adult↗
PubMed1991

Open-door maxillotomy approach for lesions of the clivus.

The transpalatal route to the clival region has been used to approach both extradural and intradural lesions. Classic transpalatal surgery, however, entails a partial splitting of the soft palate or some form of palatal retraction, which leaves behind a bony palate that hinders surgical exposure. When necessary, operative exposure can be enhanced by an open-door maxillotomy approach that uses a combination of a Le Fort I osteotomy of the maxilla and a paramedian sagittal split of the hard palate. The nasal septum is translocated to create a wide contiguous oronasal aperture through which the clival region can be reached unobstructed. This technique was used in three patients. No significant complications were observed in any patient. Features of this extended transpalatal approach, including indications and adjunctive measures to minimize potential complications, are discussed.

Journal Article↗
PubMed1990

The operative management of basilar impression in osteogenesis imperfecta.

Four patients with osteogenesis imperfecta and neurologically significant basilar impression have been treated over the past 8 years. The experience has resulted in changes in our therapeutic strategy for this particularly difficult problem. These cases are discussed with respect to the disease process, neurological involvement, radiological findings, and modes of surgical therapy. The errors in management as well as the success resulting from our learning experience are described. Currently, we recommend the extensive removal of the anterior bony compression by a transoral approach. This should be followed by a posterior rigid fixation that transfers the weight of the head to the thoracic spine, in an effort to prevent further basilar invagination.

Adult↗