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Biomedical subjects

M K Lyons

Publications and source records attributed to M K Lyons.

26 records · Page 2Linked to original sources

Primary spinal epidural non-Hodgkin's lymphoma: report of eight patients and review of the literature.

Eight patients treated for histologically confirmed primary spinal epidural non-Hodgkin's lymphoma diagnosed between January 1979 and August 1989 (6.6% of all cases of intraspinal lymphoma) were studied. There were six men and two women. The median age was 70 years (range, 43-80 yr). Patients sought treatment for a prodrome of back pain (median duration, 3 mo) followed by an acute neurological deterioration (median duration, 6 d). The most common findings were a discrete sensory level in 5 patients, hyperreflexia in 5 patients, and paraparesis or paraplegia in 5 patients. Radiographically, there was an absence of bony destruction by these tumors. All patients underwent a decompressive laminectomy, subtotal tumor resection, and spinal irradiation (median dose, 3800 cGy). Two patients had low-grade lymphomas (one B cell and one T cell), and 6 patients had intermediate-grade lesions (six B cell). Two patients with B-cell lymphomas (one low-grade and one intermediate-grade) developed metastatic disease 15 and 17 months after the initial diagnosis; no evidence of lymphoma developed in the other 6 patients. The median survival was 22 months (range, 2-71 mo). Lymphoma was the cause of death in only 1 of the 4 patients who died, and the 4 younger patients are alive and well. Primary spinal epidural non-Hodgkin's lymphoma should be a diagnostic consideration in the older patient who seeks treatment for spinal cord compression manifested by a prodrome of back pain, followed by a rapid neurological deterioration, normal plain spine radiographs, and neuroimaging consistent with an extradural compressive lesion. Surgery for this diagnosis followed by spinal irradiation should result in significant neurological improvement.

Adult↗

Computer-assisted stereotactic biopsy and volumetric resection of thalamic pilocytic astrocytomas. Report of 23 cases.

Twenty-three cases of pathologically verified thalamic pilocytic astrocytomas diagnosed at computer-assisted stereotactic biopsy and/or volumetric resection at the Mayo Clinic between January 1985 and October 1990 were reviewed. Computer-assisted stereotactic volumetric resection was performed in 19 patients. Postoperative imaging demonstrated no residual contrast-enhancing tumor in 14 patients and a small amount of contrast-enhancing tumor (less than 5% of the original tumor volume) in 5 patients. Biopsy only was performed in 4 patients: 2 with primarily cystic tumors successfully treated with stereotactic instillation of 32P, and 2 patients with stable (nonprogressive) deficits. There was 1 operative death; a patient with tumor extending into the midbrain became comatose and died 10 days after surgery. The remaining 22 patients are alive and well. Computer-assisted stereotactic volumetric resection of thalamic pilocytic astrocytomas can be performed with low morbidity and a favorable long-term prognosis.

Adolescent↗

Basic fibroblast growth factor promotes in vivo cerebral angiogenesis in chronic forebrain ischemia.

This experiment was designed to determine if intraventricular administration of basic fibroblast growth factor (bFGF) could promote cerebral angiogenesis in a model of mild chronic forebrain ischemia. Wistar rats underwent bilateral carotid artery ligation. Animals received intraventricular injections of bFGF every 4 days for 28 days. Basic fibroblast growth factor caused a significant dose-dependent increase in capillary density compared to ischemic controls in all regions examined. These results support the hypothesis that chronic intraventricular administration of bFGF induces in vivo cerebral angiogenesis.

Animals↗

Corticotropin releasing factor antagonist reduces ischemic hippocampal neuronal injury.

This experiment tested the hypothesis that corticotropin-releasing factor (CRF) contributes to hippocampal ischemic injury. The antagonist to CRF (alpha-CRF) was administered intraventricularly 15 min prior to 10 min of transient forebrain ischemia in the Wistar rat. alpha-CRF demonstrated a neuroprotective effect in a dose-dependent manner most notable in CA1. There was also an increase in postischemic EEG recovery. It is postulated that CRF contributes to hippocampal ischemic injury through increased neuronal activity.

Animals↗

Cerebral angiotropic large cell lymphoma (neoplastic angioendotheliosis): therapeutic considerations.

Cerebral angiotropic large cell lymphoma (neoplastic angioendotheliosis) is a rare disease with a particular propensity to affect the central nervous system by vascular occlusion. Because the disease is rare and there are no specific diagnostic procedures apart from cerebral biopsy, it is difficult to diagnose in life. Accordingly, chemotherapy or radiotherapy has only rarely been attempted and their effectiveness is uncertain. We established the diagnosis in a 62-year-old patient by cerebral biopsy and observed remission following institution of combination chemotherapy. Unfortunately, neurologic deterioration recurred during maintenance chemotherapy. We identified 30 patients in the literature who initially presented with definite central nervous system manifestations and whose clinical conditions were described sufficiently enough for comparison with our case. Eleven patients had the diagnosis made in life, but only 5 received chemotherapy other than corticosteroid hormones. Our patient's survival for 16 months exceeded that in the majority of the 30 reported cases. Intense anti-lymphoma chemotherapy, and possibly radiotherapy, may be beneficial and should be studied in this otherwise rapidly fatal disease. It seems certain that early diagnosis is essential if therapeutic intervention is to be successful.

Antineoplastic Combined Chemotherapy Protocols↗

Posterior fossa ependymomas: report of 30 cases and review of the literature.

Thirty patients with histologically confirmed posterior fossa ependymomas operated on between January 1976 and December 1988 were reviewed. The median age was 44 years (range, 1-69 yr). There were 7 children (aged 5 yr or younger) and 23 adults (aged 16 yr or older). There were 18 female patients and 12 male patients. Headache, nausea and vomiting, and disequilibrium were the most frequent symptoms. The most common findings were ataxia and nystagmus. Gross total resection was performed in 8 patients (27%), subtotal resection in 21 patients (70%), and biopsy in only 1 patient (3%). Tumors were low grade in 73% and high grade in 27%. Twenty-seven patients underwent posterior fossa radiotherapy (median dose, 5400 cGy). Fourteen patients also underwent spinal irradiation (median dose, 3520 cGy). Age was the only significant prognostic factor identified (P less than 0.01). The 5-year survival rates were 76% for adults and 14% for children. All 14 patients who died had recurrent or residual tumor at the primary site. This review suggests that in patients with primary posterior fossa ependymomas the following is true: 1) the young patient (5 yr old or younger) has a poor prognosis; 2) there was a trend toward a better 5-year survival rate with a gross total resection; 3) if recurrence occurs, it will be at the primary intracranial site; and 4) symptomatic spinal seeding does not occur frequently.

Adolescent↗

Cerebrospinal fluid physiology and the management of increased intracranial pressure.

Increased intracranial pressure can result in irreversible injury to the central nervous system. Among the many functions of the cerebrospinal fluid, it provides protection against acute changes in venous and arterial blood pressure or impact pressure. Nevertheless, trauma, tumors, infections, neurosurgical procedures, and other factors can cause increased intracranial pressure. Both surgical and nonsurgical therapeutic modalities can be used in the management of increased intracranial pressure attributable to traumatic and nontraumatic causes. In patients with cerebral injury and increased intracranial pressure, monitoring of the intracranial pressure can provide an objective measure of the response to therapy and the pressure dynamics. Intraventricular, intraparenchymal, subarachnoid, and epidural sites can be used for monitoring, and the advantages and disadvantages of the various devices available are discussed. With the proper understanding of the physiologic features of the cerebrospinal fluid, the physician can apply the management principles reviewed herein to minimize damage from intracranial hypertension.

Absorption↗