Ar. Varma et al., A TC-99M-HMPAO SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY STUDY OF LEWY-BODY-DISEASE, Journal of neurology, 244(6), 1997, pp. 349-359
The purpose of this study was to investigate patterns of Tc-99m-HMPAO
single-photon emission computed tomography (SPECT) abnormality in Lewy
body disease (LED) and to compare findings with those encountered in
Alzheimer's disease (AD). The study group comprised 20 consecutive pat
ient referrals fulfilling clinical criteria for LED. All patients had
fluctuating cognitive impairment and 'subcortical' dysfunction with or
without perceptuospatial and/or linguistic impairment. Six patients h
ad asymmetrical signs of parkinsonism (three left-sided and three righ
t-sided), and 14 patients had symmetrical features of extrapyramidal i
nvolvement. Tc-99m-HMPAO SPECT imaging was performed on LED patients a
nd findings compared with those of 57 patients with 'probable' AD and
11 normal age-matched controls. Within the LED and AD groups, patterns
of cortical and subcortical blood-flow abnormality were compared with
patterns of cognitive and neurological breakdown. LED was associated
with bilateral posterior cortical blood flow abnormality, a pattern st
rikingly similar to that found in AD. Within the LED group, cortical b
lood-flow abnormality was found to reflect patterns of neurological dy
sfunction (parkinsonism) indicative of subcortical involvement. In con
trast, cortical blood-flow changes did not reflect patterns of neurops
ychological impairment suggestive of cortical dysfunction. Within the
AD group, cortical blood-flow changes were mirrored by the pattern of
neuropsychological impairment. Findings support the notion that cortic
al bloodflow abnormality in LED might reflect a combination of direct
cortical pathology and cortical deafferentation secondary to subcortic
al Lewy body pathology. It would appear that Tc-99m-HMPAO SPECT imagin
g is of limited value in the clinical differentiation of LED and AD.