Lathyrism is a disease of poor underdeveloped countries where large amounts of pulse Lathyrus sativus (Kesari dal) are consumed. This pulse is extensively cultivated in India like North Bihar, United Provinces, Madhya Pradesh, Bengal, Maharashtra, Mysore and Andhra Pradesh. It is mainly confined to countries where different kinds of pulses are used as staple food.
Thus cases of lathyrism are also reported from Spain, Greece, Italy and Algiers. The dehusked seeds of the plant resemble Bengal gram or Toor Dal, so they are often used as adulterants of these pulses. The plant does not require any rain or water for its growth since it is a drought resistant crop and thrives even under adverse circumstances. A poor rainfall is often followed by an epidemic of lathyrism.
The alcoholic extract of lathyrus sativus seeds contains a water soluble toxin (BOAA) which is distributed mainly in the husk and cotyledons of the plant. It is a disease which primarily involves males more as compared to females (10:1) in the age group of 15-35 years. Women are said to be less affected because of protective effect of female hormones. Other members of the family may be affected.
A number of factors ranging from amount or duration of consumption of the Dal, individual susceptibility to an auto immune mechanism have been suggested. The most obvious pathological changes are chronic sclerosis of the spinal cord involving posterior and lateral columns as well as degeneration of anterior horn cells.
Clinical features of lathyrism
The earliest symptom is agonizing pain in the calf muscles especially at night. Acute muscle spasms produce painful lumps known as ‘lodakas’ which last for 10-15 minutes and pass off with massage or spontaneously. It is said that if the consumption of the Dal is stopped at this stage the disease may be halted and process reversed.
Classically lathyrism disease presents in one or the other of three ways.
It occurs in more than 50% of cases and starts as acute attack which comes when the patient is working. The person is seized with stiffness and heaviness of legs and inability to walk. It progresses with increasing stiffness and makes the person incapable of walking. This may develop over a week to month.
After the initial muscle spasms, in a week or two when patient does physical exertion like running or jumping, there is increase in stiffness and heaviness of the limbs. Person may become paralyzed and bed ridden.
It is the commonest form of presentation when person complains of back ache, burning pains and weakness of the legs and an awkward gait. The disease increases progressively, the spasticity increases and a scissor type of gait develops.
At this level patient requires either a stick or crutch to maintain balance. This is called one- stick level. Further progress of the disease spreads over years and results in ‘Two stick stage’ when legs become more spastic or rigid.
Movements of the limbs are restricted and now couple of crutches is required to move. On examination the physical signs shall depend on the stage at which the patient presents. In some there is complete paralysis of the lower limbs.
Main involvement is spastic paraplegia with exaggerated tendon jerks and extensor response plantar. Predominantly there is involvement of the cord between T12 and Li segments. The upper limbs usually escape and there is no wasting of muscles. There is no sensory loss and no involvement of organic reflexes. Rarely sensory peripheral neuropathy may develop. Last stage is ‘Crawler stage’.
Treatment of lathyrism
There is no specific treatment once it develops Analgesics, generous diet and large doses of Vitamin B complex may help.
Patient should avoid damp and wet climate. At the earliest signs of stiffness and muscle spasm consumption of Dal must be stopped. The toxic factor present in the seeds of lathyrus sativus can be removed by a process of para boiling. Prognosis of lathyrism depends on the stage at which the patient presents.