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Biomedical subjects

M R Swenson

Publications and source records attributed to M R Swenson.

29 records · Page 2Linked to original sources

Eales' disease with central nervous system infarction.

Eales' disease is a noninflammatory occlusive disorder of the retinal vasculature that causes recurrent hemorrhages into the retina and vitreous and ischemic changes in the eye. Extraocular manifestations of Eales' disease are rare and limited to the central nervous system. We report the case of a patient with Eales' disease and ischemic stroke, and we review the neurologic manifestations of this primarily ophthalmologic vasculopathy.

Cerebral Infarction↗

Photic sneeze reflex in nephropathic cystinosis.

Photic induced sneeze is a reflex that occurs in certain individuals after exposure to bright light. Cystinosis is an autosomal recessive inborn error of metabolism in which nonprotein cystine accumulates within lysosomes. The pathognomonic ocular manifestation of cystinosis is corneal crystal deposition. We observed photic induced sneezes during ophthalmoscopic examination in five of 19 patients with nephropathic cystinosis (26%). We report on this observation and discuss possible pathophysiological mechanisms for photic induced sneezing in cystinosis.

Cystinosis↗

Nerve-roots of the cauda equina. The effect of hypotension and acute graded compression on function.

The influence of hypotension on the function of nerve-roots of the cauda equina under acute graded compression was studied with use of an established porcine model. In twenty adult miniature pigs, the nerve-roots of the cauda equina were compressed at pressures of zero (sham), fifty, 100, or 200 millimeters of mercury, and hypotension was induced with sodium nitroprusside. Compression was maintained for two hours, and a ninety-minute period of recovery followed. The nerve-roots were monitored electrophysiologically throughout the experiment. To assess the effect of compression and hypotension on the function of the nerve-roots, values of afferent and efferent amplitude and nerve-conduction velocity were compared with values in twenty adult miniature pigs that had similar graded compression without hypotension. Hypotension significantly affected efferent and afferent amplitudes at the end of the compression period; the effect remained significant at the end of the recovery period. The most profound effect of hypotension occurred during compression at fifty millimeters of mercury--a pressure that had no effect on the function of the nerves in normotensive animals.

Animals↗

Migrainous stroke.

Twenty-two patients with acute migraine-associated stroke were prospectively evaluated; 91% were female, and 23% had a prior history of presumed migrainous stroke. The incidences of major stroke risk factors and mitral valve prolapse were no higher for the study group than for the general population of similar age. Computed tomography, magnetic resonance imaging, or radionucleotide scanning of the brain was performed on all patients, and demonstrated ischemic or hemorrhagic infarction in 12 (55%). Cerebral arteriography revealed abnormalities related to the acute stroke in five (42%) of 12 cases overall, and in four (67%) of six studies performed within 72 hours of stroke onset; one patient (8%) suffered significant complications from arteriography. Although a variety of processes, alone or in combination, may contribute to migrainous stroke, extracranial and/or intracranial vasospasm appears to play a major role in at least some cases.

Acute Disease↗

Cerebrovascular complications of L-asparaginase therapy.

L-Asparaginase, commonly used in combination chemotherapy in the treatment of acute lymphoblastic leukemia, has been associated with hemorrhagic and thrombotic cerebrovascular events. Thrombosis of the cerebral veins or dural sinuses is common, and may be associated with either hemorrhage or infarction. This syndrome generally occurs after a few weeks of therapy, and may occur after L-asparaginase therapy is completed. Complications appear to result from depletion of plasma proteins involved in coagulation and fibrinolysis. We now report two additional cases of cerebrovascular complications associated with L-asparaginase therapy. We review the previously reported cases and discuss the clinical presentation, pathophysiology, and suggested treatment of this syndrome.

Acute Disease↗

Neurogenic bladder from occult herpes zoster.

Active infection with herpes zoster may cause acute urinary retention, especially when it involves sacral dermatomes. Although frank retention usually develops days to weeks after eruption of the typical rash, bladder incompetence infrequently develops first, raising concern over other, more ominous etiologies. In the case presented, rash appearance was delayed until six weeks after the initial onset of urinary retention, a much longer interval than previously reported. Occult herpes zoster infection should be considered in patients presenting with an acute neurogenic bladder of obscure cause.

Acyclovir↗

Neurogenic claudication due to pseudospondylolisthesis.

Pseudospondylolisthesis is a subluxation of the lumbar vertebrae due to incompetent facet joints. The resulting stenosis of the lumbar spinal canal may impinge on the nerve roots of the cauda equina and induce neurogenic claudication. This syndrome is difficult to distinguish clinically from lower extremity claudication of vascular etiology. Accurate diagnosis requires radiographic examination of the spine.

Diagnosis, Differential↗

Glomus jugulare tumor.

A 53-year-old woman with left vocal cord paralysis was seen for sharp shooting pains in the left side of the neck and the left shoulder and upper arm. Glomus jugulare tumor was diagnosed, based on clinical findings and results of angiography and computed tomography. Because surgery was contraindicated, radiotherapy was used. The patient's symptoms resolved within three months, and she had had no further problems. Glomus jugulare tumor should be considered in the differential diagnosis of adult chronic otitis, deafness, tinnitus, and dysfunction of the lower cranial nerves.

Diagnosis, Differential↗

Preservation of evoked potentials in a case of anterior spinal artery syndrome.

A case of anterior spinal artery syndrome is presented for which there are neurologic, electrophysiologic, and pathologic correlations. Ten days prior to her death, a 52-year-old hypertensive female developed severe chest pain and lower extremity weakness. A diagnosis of aortic dissection resulting in an anterior spinal artery syndrome was made. Intraoperative posterior tibial somatosensory evoked potentials demonstrated normal morphology and latencies. Autopsy revealed an infarction of the anterior portion of the thoraco-lumbar spinal cord with preservation of the posterior columns. This case demonstrates that severe spinal cord injury can exist in the presence of preserved somatosensory evoked potentials.

Aortic Dissection↗