Extrapyramidal signs should be sought more often in Alzheimer's disease

EDITOR,—Yoav Ben-Shlomo and colleagues restate the rarity of the existence of the amyotrophic lateral sclerosis-parkinsonism-dementia complex in areas other than the Pacific focus.1 Colleagues and I have reported on a patient who had amyotrophic lateral sclerosis and dementia but in whom tremor was absent and the bradykinesia that was present was attributed to severe motor paralysis.2 Parkinsonism was therefore not diagnosed. In the light of experience since, however, I realise that we did not properly seek rigidity. It is now my practice to test for rigidity in both elbows and both wrists by rapidly flexing and extending these joints (which should hopefully be fully relaxed) 50 times or until cogwheel rigidity is felt. An observer of the examination can usually see this phenomenon simultaneously with its becoming apparent to the examiner. Fifty times is an arbitrarily chosen figure.

This method, for which I do not claim originality, recently enabled the demonstration of rigidity in these joints after an average of only 12 passive movements. The patient was a 65 year old woman with a five year history of progressive dementia of the Alzheimer type. Investigations, including modern imaging techniques,had not shown alternative explanations for the symptoms. There was no tremor, bradykinesia, or postural instability. The glabella tap sign was present.

The papers that state the criteria for diagnosing extrapyramidal signs do not precisely describe how to elicit muscular rigidity.3 4 Possibly,searching more often for the physical sign described will reduce the wide variation in the reported frequency of extrapyramidal signs in patients with Alzheimer's disease.5