[abstract] CASE CONTROL STUDY OF DECOMPRESSION ILLNESS USING 99Tcm-HMPAO SPECT

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[abstract] CASE CONTROL STUDY OF DECOMPRESSION ILLNESS USING 99Tcm-HMPAO SPECT

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Title: [abstract] CASE CONTROL STUDY OF DECOMPRESSION ILLNESS USING 99Tcm-HMPAO SPECT
Author: Hodgson, M; Smith, DJ; MacLeod, MA; Houston, AS; Francis, TJR
Abstract: In a preliminary report in 1989, Adkisson et al. used 99Tcm (Tc-99m)HMPAO SPECT to provide evidence for cerebral perfusion deficits in 28 cases of dysbarism (1). The report caused concern because these deficits were found even in cases in which the clinical manifestations were apparently limited to the spinal cord. To address this issue further, a case-control study of cerebral perfusion using Tc-99m HMPAO SPECT is presented. Four groups of 10 subjects were studied: a) divers scanned on average 11 days after treatment for neurological decompression illness (DCI), b) divers scanned three to five years after treatment for neurological DCI, c) diver controls, and d) population controls. All groups were matched for age and the divers were further matched for general diving experience. The scans were randomized and reported blind to history. Experience with the technique suggests that only perfusion deficits of 12 percent or greater are of probable clinical significance. Using this criierion, 8 new cases, 6 old cases, 5 diver controls, and 5 nondiver controls demonstrated 'significant' deficits. Despite a trend towards larger numbers of deficits in individuals with DCI, the four groups were statistically indistinguishable. No correlation was found between the location of the perfusion deficits and the clinical presentation in the two groups with a history of DCI. There was a higher proportion of positive results in the diver and population controls than might be expected even using high percentage cutoffs. This was surprising since no abnormalities were found in their history or on careful clinical examination. We were unable to find other published Tc-99m HMPAO SPECT series reporting controls with which we could compare our data. One explanation for these findings is that DCI generates a diffuse cerebral injury for which the scan is insufficiently sensitive to discriminate from normal variation, thereby producing an unacceptably high false-positive rate as presently analyzed. With the lack of a distinct positive/negative split, this study has insufficient statistical power for firm conclusions to be drawn. However, these results do indicate that Tc-99m HMPAO SPECT scanning requires further evaluation before clinical significance can be ascribed to perfusion deficits found in divers. 1. Adkisson GH, Macleod MA, Hodgson M, Sykes JJW, Smith F, Strack C, Torok 2. Pearson RR. Cerebral Perfusion Deficits in Dysbaric Illness. Lancet 1989; 2:119-121.
Description: Abstract of the Undersea and Hyperbaric Medical Society Annual Scientific Meeting held June 19-23, 1991 at San Diego Princess Resort, San Diego, CA
URI: http://archive.rubicon-foundation.org/6402
Date: 1991

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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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