DECOMPRESSION SICKNESS

By Charbel on May 18, 2011 | In Health, NEUROLOGY

DECOMPRESSION SICKNESS
LEON D. PROCKOP

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In scuba diving, caisson work, flying, and simulated altitude ascents, rapid reduction in ambient pressure may allow the formation of bubbles from inert gases (nitrogen in particular) that are normally dissolved in body tissues. Resultant lesions involve the limbs, cardiopulmonary system, and central nervous system. In divers, most neurologic lesions affect the spinal cord. In fliers, cerebral damage is most common.
The incidence of decompression sickness in divers is between 1% and 30%. Although the spinal cord is the most common site of neurologic lesions, encephalopathy is also well-described. Electrophysiologic studies, experimental models, and isolated postmortem examination of patients show predominant involvement of the posterolateral and posterior columns in the watershed areas of the thoracic, upper lumbar, and lower cervical cord. Ischemic perivascular lesions are usually confined to the white matter, but subsequent petechial hemorrhage may occur and extend into the gray matter. Lesions result from bubbles occluding vessels or directly disrupting tissue. Coincident intraarterial embolism may cause cerebral damage.
With cord damage, back pain is followed by leg paresthesia, paresis, and urinary retention. When the brain is affected, neurologic signs and symptoms include visual impairment, vertigo, hemiparesis, loss of consciousness, and seizures. Unless recompression is achieved promptly, the signs, including paralysis, may become permanent.
Serious manifestations of decompression sickness, including any neurologic signs, are a medical emergency. Current therapy consists of recompression in a hyperbaric chamber and the concurrent administration of high concentrations of inspired oxygen. Results of treatment vary, but the sooner recompression is begun, the better the outcome. For chamber locations, physicians should contact the local United States Coast Guard marine and air rescue centers listed in telephone directories in coastal areas.
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