Neuro-Ophthalmologic Findings in Konzo, an Upper Motor Neuron Disorder in Africa

Abstract

Konzo was associated with optic neuropathy and a few patients had nystagmus. Although the etiopathogenesis of this optic neuropathy remains to be elucidated, the symmetry of the involvement suggests a toxic origin. We suggest that cyanide causes the neuro-ophthalmological damage in konzo. However, the optic neuropathy in konzo patients does not resemble the features of the epidemic optic neuropathy in Tanzania, Cuba or Nigeria, Leber's hereditary optic neuropathy, tobacco amblyopia or vitamin B deficiency.

Determinants of cognitive performance in children relying on cyanogenic cassava as staple food

“…those of exposure to cyanogenic compounds such as the urinary levels of thiocyanate (SCN) do display poor fidelity to the individual diseases listed above (Lancet, 1984, Banea-Mayambu et al, 1997, Cliff et al, 1999). Third, there appear to be a wide spectrum of neuropathological features in the same individual diseases (Oluwole et al, 2000, Tshala-Katumbay et al, 2001b, Tshala-Katumbay et al, 2002a, Tshala-Katumbay et al, 2002b, Mwanza et al, 2003b, Madhusudanan et al, 2008). As such, the “continuum” model appears suitable for studies aimed at elucidating the biomarkers of cassava-associated neurodegeneration.…”

Etiology of Konzo, epidemic spastic paraparesis associated with cyanogenic glycosides in cassava: Role of thiamine deficiency?

“…Visual evoked potential studies in Konzo patients indicated the presence of axonal loss in the prechiasmal visual pathways, indicative of an optic neuropathy [39]. The presence of optic neuropathy has also been confirmed by neuroophthalmological studies [40]. Optic neuropathy is known to result from a diet-induced deficiency of thiamine [41].…”

Upper Motor Neuron Disorders in Africa

“…Neuroophthalmological studies have confirmed the presence of optic neuropathy in konzo patients, with visual impairment, defect of visual fields and temporal pallor of the optic discs. 43 Rotatory nyastagmus is seen in some affected people. Among moderate and severely disabled konzo subjects, some have dysarthria due to pseudobulbar palsy.…”