[abstract] OCCULT SPINAL CORD DAMAGE IN CLINICALLY NORMAL PIGS FOLLOWING DIVING.

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[abstract] OCCULT SPINAL CORD DAMAGE IN CLINICALLY NORMAL PIGS FOLLOWING DIVING.

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Title: [abstract] OCCULT SPINAL CORD DAMAGE IN CLINICALLY NORMAL PIGS FOLLOWING DIVING.
Author: Dick Jr, EJ; Broome, JR
Abstract: BACKGROUND: In a study of risk factors for neurological DCI using a pig model, some pigs with no post dive clinical evidence of neurological dysfunction, nevertheless, following necropsy, had histological evidence of substantial CNS damage. METHODS: Male, castrated, Yorkshire swine (Wt. 18-22 kg), from a closed breeding colony, are dived on air to 200 fsw in a dry chamber. Bottom time is standardized at 24 min including 5 min compression. Decompression rate is 60 fsw/min. Pigs are observed for DCI at the surface and those with no subjective neurological signs are assessed as "normal" if they can run on a treadmill without gait disturbance at 1 and 24 hrs post-dive. At necropsy 1 day post-dive the brain and spinal cord are removed for histological examination. Samples 1 em. in length are taken at the cervical, thoracic, lumbar, and sacral levels of the spinal cord and cut in cross and longitudinal section. Brainstem, cerebellum, and cerebrum are sampled as well. All sections are cut at 6 microns and stained with Hematoxylin and Eosin; sections demonstrating histologic lesions are additionally cut at 20 microns and stained by a Luxol Fast Blue and PAS procedure to evaluate myelin. RESULTS: After a single dive with no clinical neurological sequelae and no observable gross lesions at necropsy, 4 of 20 pigs had histological evidence of CNS damage: Within the spinal cord white matter, 2 pigs had focal or multifocal areas of spongy change with infiltration by activated microglial (Gitter) cells. Within these areas axons were disrupted and swollen, with distended myelin sheathes and demyelination. Also in the white matter of 1 of these 2 pigs, there was segmental fibrinoid necrosis of a small artery with a focal area of minimal perivascular hemorrhage and erythrophagocytosis. A third pig had multifocal mild hemorrhage in the spinal cord white matter with erythrophagocytosis and minimal spongiosis. The fourth pig had areas of minimal spongiosis in the white matter, segmental fibrinoid necrosis of a small artery in the cord grey matter, and multifocal mild perivascular hemorrhage in the midbrain. Such lesions were not observed in non-dived control pigs. CONCLUSION: The findings provide further evidence that diving may cause clinically unsuspected CNS damage -an issue with important implications for the long-term health of both professional and recreational divers. (Supported by NMRDC Work Unit No. M0099.01C-1053).
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting held June 22-26, 1994. Westin Hotel, Denver, Colorado (http://www.uhms.org)
URI: http://archive.rubicon-foundation.org/5711
Date: 1994

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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