Clinical and magnetic resonance features of the classic and akinetic-rigid variants of Huntington's disease
D. Oliva, F. Carella, M. Savoiardo, L. Strada, P. Giovannini, D. Testa, G. Filippini, T. Caraceni and F. Girotti
Divisione di Neurologia, Istituto Nazionale Neurologico C. Besta, Milano, Italy.
We studied 32 patients with confirmed Huntington's disease (HD); six (mean
age, 31.7 years) had the akinetic-rigid form and 26 (mean age, 46.1 years)
had the classic hyperkinetic form. Clinical examination included a count of
abnormal involuntary movements, motor self-sufficiency evaluation by the
Physical Disability Rating Scale, cognitive function assessment by the
Mini-Mental State examination, and a verbal fluency test. Magnetic
resonance imaging permitted measurement of bicaudate diameter, a sensitive
indicator of caudate atrophy in HD. Patients with the akinetic-rigid form
of HD were younger and had earlier disease onset than those with the
classic form of HD. All patients with akinetic-rigid HD (group 1) had
striatal hyperintensity on T2-weighted magnetic resonance images; seven
patients with classic HD (group 2) had a similar abnormality. Groups 1 and
2 were in fact similar in all other respects, except that the number of
abnormal involuntary movements was greater in group 2. Groups 1 and 2
together had significantly younger age at onset, lower Mini-Mental State
Examination score, more severe motor disability, worse verbal fluency test
result, and greater bicaudate diameter than the 19 patients with classic HD
without magnetic resonance signal abnormality (group 3) and appear to be a
uniform population, distinct from group 3. The abnormalities on magnetic
resonance images indicated greater striatal damage in groups 1 and 2, which
could be the neuroanatomic substrate of their greater motor and cognitive
compromise.
