Some Neurological Aspects of Medical Geography

The first comprehensive treatise on geographical pathology was written by a German physician, August Hirsch (1886). His work, now nearly a century old, is still of great interest to read. For example, quite by chance I came across a description of an unusual form of brachial neuralgia which was then prevalent in Iceland and affected chiefly women who had to milk ewes. This 'nalardofi', as it was called, was characterized by pain in the arm, prickling sensations in the hand and fingers and often sensory impairment. On reflection it appears not improbable that it was the same as the complaint which we now describe as 'the carpal tunnel syndrome'. Another topic of neurological interest discussed by Hirsch was leprosy. To-day, of course, the disease is much less prevalent but there are still some 11 million lepers in India and Pakistan (MacNalty 1962), and in Africa, some 400,000 in Nigeria alone (Buchanan & Pugh 1955). Neither is leprosy unknown in Europe because in Spain and Portugal (World Health Organization 1959) and in Italy (Argenta 1961) there is a surprisingly large number of affected persons; in London 78 cases were reported last year (Stevenson 1961), a circumstance which can be correlated with the big influx to Britain in recent years of immigrants from endemic areas within the Commonwealth. Deficiency diseases of the nervous system such as pellagra and beri beri have also much geographical interest for, as Kinnier Wilson (1941) remarked, 'What can be the common factor when a woman in the Orkney Islands, an Egyptian peasant, a small boy in London, a lunatic in an English asylum, a native of Nyasaland and a governess in a well-to-do family in the Southern United States all suffer from pellagra ? ' The same problem puzzled Hirsch, who did not know the answer, and his observation that the disease tended to occur especially within certain geographical zones, those parts lying between the 42nd and 46th parallels of latitude, is of interest to-day when one reflects on the somewhat similar association that is known to exist between the prevalence of disseminated or multiple sclerosis and latitude. Ergotism was confused with pellagra until the role of poisonous alkaloids contained in the fungus responsible was recognized. An outbreak occurred as recently as 1951 in the French village of Pont St Esprit (Gabbai et al. 1951, Lancet 1951, Johnson 1952), but subsequent reports indicate that there were unusual clinical features and that the evidence in favour of ergotism was equivocal. Akin to this toxic affection of the nervous system, however, and still endemic at times in parts of India (Dastur 1961), is lathyrism, the spastic paraplegia induced in times of want by admixture of grain with certain toxic weeds. Other modern examples of toxic nervous affections occurring epidemically, although not quite in the same category, being man made, are the recent outbreaks of triorthocresylphosphate poisoning in Morocco (Smith & Spalding 1959), and Minamata disease (Kurland et al. 1960, McAlpine & Araki 1958) in the island of Kyushu, Japan, which since 1953 has killed nearly 40% of the 83 persons affected by it.