Not Parkinson’s disease: neurologists’ mistakes with a diversion into adult hydrocephalus

The metaphorical barn door applies to the diagnosis of parkinsonism by practising neurologists, and most of these patients have Parkinson’s disease. But the minority have another cause and this may lead to bad loss of face by the neurologist, as I have myself experienced. And on occasion the potent current medical and surgical anti-parkinsonian treatments may prove very mistaken.

My first exposure to “not Parkinson’s disease” were the survivors of the encephalitis lethargica epidemics of the first decades of the 20th century, seen in London in the 1950s and 1960s. The patients differed from those with Parkinson’s disease in having static rather than progressive disabilities, with predominant akinesia, autonomic disorders, and oculogyric crises. One often aggravated their distress by overenthusiastic use of anti-cholinergic drugs. The advent of L-dopa, as related dramatically to the lay public in 1973 by Oliver Sacks in his best-seller Awakenings, brought relief. Then, and since, a rare but perennial problem of not Parkinson’s disease was the medicolegal conundrum of post-traumatic parkinsonsism; the problem lay not in diagnosis or management, but in attributability where the lawyers’ balance of probabilities was bound to err.

In the 1950s a new manifestation of “not Parkinson’s disease” emerged with the successful use of psychotropic drugs such as the phenothiazines. This drug-induced parkinsonism often had dystonic features. The patients were easily spotted by taking a proper drug history, and would remit …