Objectives-The term tropical ataxic neuropathy (TAN) is currently used to d
escribe several neurological syndromes attributed to toxiconutritional caus
es. However, TAN was initially proposed to describe a specific neurological
syndrome seen predominantly among the Ijebu speaking Yorubas in south west
ern Nigeria. In this study, the prevalence of TAN was determined in Ososa,
a semiurban community in south western Nigeria described as endemic for TAN
in 1969, and its neurological features were compared with Strachan's syndr
ome, prisoners of war neuropathy, the epidemic neuropathy in Cuba, and konz
o.
Methods-A census of Ososa was followed by door to door screening of all sub
jects aged 10 years and above with a newly designed screening instrument. S
ubjects who screened positive had a neurological examination, and the diagn
osis of TAN was made if any two or more of bilateral optic atrophy, bilater
al neurosensory deafness, sensory gait ataxia, or distal symmetric sensory
polyneuropathy were present.
Results-A total of 4583 inhabitants were registered in the census. Of these
, 3428 subjects aged 10 years and above were screened. The diagnosis of TAN
was made in 206 of 323 subjects who screened positive for TAN. The prevale
nce of TAN was 6.0%, 3.9% in males and 7.7% in females. The highest age spe
cific prevalence was 24% in the 60-69 years age group in women.
Conclusion-The occurrence of TAN in Ososa continues at a higher prevalence
than was reported 30 years ago. Its neurological features and natural histo
ry do not resemble those described for Strachan syndrome, epidemic neuropat
hy in Cuba, or konzo. The increasing consumption of cassava foods linked to
its causation makes TAN of public health importance in Nigeria, the most p
opulous African country.