Neurosurgery
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The effects on cerebral metabolism and the electroencephalogram (EEG) of combining hypocapnia with hypotension have been only incompletely examined. The present study examined the possibility that hypocapnia may worsen the cerebral metabolic and EEG disturbances caused by hypotension. Cerebral metabolism and the EEG were studied at three levels of hypotension during hypocapnia (PaCO2 = 20 mm Hg) in dogs under light halothane anesthesia. ⋯ Cerebral metabolic values were unchanged at a MAP of 60 mm Hg. At MAP less than or equal to 50 mm Hg, power in the beta 1 spectrum, brain tissue phosphocreatine, and the cerebral energy charge all decreased. At a MAP of 40 mm Hg, the cerebral glucose value decreased and the lactate/pyruvate ratio increased.(ABSTRACT TRUNCATED AT 250 WORDS)
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Case Reports
Spontaneous migration of a bullet in the spinal subarachnoid space causing delayed radicular symptoms.
The authors report a case of a gunshot wound to the left lower quadrant of the abdomen in a patient who initially was neurologically intact. The bullet had lodged at the T-11, T-12 level in the spinal canal. ⋯ Repeat x-ray films and a myelogram showed that the bullet had migrated to the L-4, L-5 level on the left. Bullet emboli and delayed sequelae of gunshot wounds to the spine are discussed.
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Sophisticated techniques for electrical stimulation of excitable tissue to treat neuromuscular disorders rationally have been developed over the past 3 decades. A historical review shows that electricity has been applied to the phrenic nerves to activate the diaphragm for some 200 years. Of the contemporary methods for stimulating the phrenic nerve in cases of ventilatory insufficiency, the authors prefer stimulation of the phrenic nerve in the thorax using a platinum ribbon electrode placed behind the nerve and an attached subcutaneously implanted radiofrequency (RF) receiver inductively coupled to an external RF transmitter. ⋯ Candidates for diaphragm pacing are those with ventilatory insufficiency due to malfunction of the respiratory control center or interruption of the upper motor neurons of the phrenic nerve. In the Yale series, there were 77 patients treated by diaphragm pacing; 63 (82%) started before 1981 and thus were available for follow-up for at least 5 years; 33 (52%) were paced for 5 to 10 years, and 15 (24%) were paced for 10 to 16. Long term stimulation of the phrenic nerves to pace the diaphragm is an effective method of ventilatory support in selected cases.
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Quantitative measurements of the epidural space between T-7 and L-4 were made in the sagittal and coronal planes utilizing x-ray films made after the injection of iodized oil into the epidural space in the low thoracic and upper lumbar areas. These data reveal a 1-mm ventral epidural space and a 2-mm lateral epidural space, with a sawtooth shape to the dorsal epidural space measuring between 1.1 and 2.9 mm at the rostral lamina and between 3.8 and 6.5 mm at the caudal lamina. Additionally, five patients with chronic pain were studied by computed tomography of T-8 to T-12, with confirmation of the sawtooth shape of the dorsal epidural space. Computed tomography showed the measurements of the epidural space at the rostral lamina to vary between 1.3 and 1.6 mm and those at the caudal lamina/interlaminar space to range from 6.9 to 9.1 mm.
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Biography Historical Article
W. W. Keen: America's pioneer neurological surgeon.
The contributions of William Williams Keen to the development of neurological surgery were greater than those of any other American surgeon in the last quarter of the 19th century. His close association with S. Weir Mitchell, the father of American neurology, spanned more than 50 years. ⋯ He made contributions to the surgical treatment of hydrocephalus, craniostenosis, torticollis, trigeminal neuralgia, and nervous system trauma. Keen's surgical texts provided an important foundation for Cushing, Frazier, and those that followed. Showered with honors as America's dean of surgery, Keen lived to see the many specialties evolve.