[Polyneuropathy deficiency among Xavante indians]

The authors present two cases of polyneuropathy deficiency among Xavante indians where the sole food was rice in case 1 and almost so in case 2. The rice consumed by these indians was processed or hulled. Intoxication by cyanide from maniot or other vegetable was excluded.

Two indians aged 18 and 25 years with a progressive history of weaness, decrease in muscular force and thinning were observed in their villages. On removal to the Hospital São Paulo, atrophy of the distal musculature of the upper and lower limbs, motor deficit distally with zero degree in the flexor musculature, abolished deep reflexes, plantar cutaneous reflex without response bilaterally, decreased tactile, painful and pallesthetic sensitivity distally in the lower limbs were noted on neurological examination of case 1. On neurological examination of case 2 proximal hyporeflexia in the upper limbs, areflexia in the distal portions of the upper and lower limbs, tactile and painful hypoesthesia in the feet, right hypoacousis were noted. Electromyography showed abnormalities compatible with symmetric sensorimotor polyneuropathy with an axonal demyelination pattern in case 1 and predominantly demyelinizing in case 2. Cerebrospinal fluid tests were normal.

Polyneuropathy was characterized by the clinical history and by neurological, electromyographic and cerebrospinal fluid tests. The diagnosis of polyneuropathy deficiency was established by the clinical history and by electromyography suggesting peripheral polyneuropathy of nutritional origin. This neuropathy deficiency does not fit myeloneuropathies such as ataxic tropical neuropathy, spastic paraparesis and Cuba neuropathy.

The Xavante polyneuropathy deficiency is caused by thiamine (vitamin B1) deficiency, that is dry beriberi, owing to consumption of industrially processed rice as sole or almost sole food. The Xavante polyneuropathy is different from the neuropathy observed among Kreen-Akrore indians and from that of adolescent indians in the Xingu Park.