Article by Dr Raghuram Y.S. MD (Ay) & Dr Manasa S, B.A.M.S
Lathyrism is a neurological disorder or neurotoxic disorder caused due to excessive consumption of certain legumes belonging to the genus Lathyrus.
Other interesting and important points about Lathyrism
Lathyrism is a neurological manifestation of nutritional disorder and one of the oldest known neurotoxic disorders, caused by excessive consumption of grass pea, Lathyrus sativus. It is a neurodegenerative disease characterized by spastic paraplegia.
It causes non progressive but irreversible spastic paraparesis.
Cases of Lathyrism are reported in Asia, Europe and Africa. Lathyrism is mainly identified in populations of Bangladesh, India and Ethiopia. It has also been from Greece, Israel, Nepal, Spain, China and West Germany. In India, cases are mainly found in Uttar Pradesh, Madhya Pradesh and Bihar.
Economically deprived villagers use Lathyrus sativus as staple food during food scarcity during droughts and famine. Its grains are used to make gruel and bread is prepared using its flour.
Types of Lathyrism
There are three types of lathyrism. Each type has different symptoms and would affect different tissues. The types of lathyrism are as below described.
1. Neuro-Lathyrism
Consumption of large quantities of Lathyrus grain – Lathyrus sativus (grass pea, chickling pea, kesari dal) to a great extent and Lathyrus cicero, Lathyrus ochrus and Lathyrus clymenum to a lesser extent, which contains ODAP neurotoxin causes Neuro-lathyrism. ODAP – Oxaly Di-Amino Propionic Acid or BOAA (Beta N-oxalyl-Amino-L-Alanine) is a toxin which is present in the legumes of the genus Lathyrus. So, one is also consuming the toxins when he or she consumes these legumes. This is a neurotoxin and would result in motor neuron death. This eventually leads to paralysis and muscle atrophy in the lower limbs.
The three modes of neuro-lathyrism manifestation include –
– Sudden onset of leg weakness while going to sleep or at the time of awakening from sleep
– Subacute onset of walking difficulty
– Insidious progression of spastic paraparesis developing over several months
2. Osteo-Lathyrism / Odoratism
This type of Lathyrism results from consumption of the seeds of sweet peas (Lathyrus odoratus) and it affects the bones and connective tissues. Therefore, Osteo-lathyrism is a skeletal disorder. In contrast with neuro-lathyrism, osteo-lathyrism is caused by a different toxin called BAPN – beta-aminopropionitrile, a metabolic product of a compound found in sprouted seeds of grass pea, lentil and pea. This toxin affects the linking of subunits of collagen found in connective tissues.
3. Angio-Lathyrism
This is yet another type of lathyrism which affects the collagen in the blood cappilaries and in mechanism it is similar to osteo-lathyrism. It is also caused by the same toxin BAPN. This condition affects the blood vessels.
History of Lathyrism
The intoxication caused by consumption of Lathyrus was first mentioned in ancient Indian scriptures, Ayurveda. The condition ‘Kalaya Khanja’ explained in Ayurveda treatises points towards a combined form of all types of Lathyrism.
A neurological disorder caused by Lathyrus seeds has been mentioned by Hippocrates, in 46 B.C. in Greece.
Evidence tells that grass pea served as a famine food during the Spanish War of Independence against Napolean.
The detainees, most of whom were the Jews, were fed exclusively with grass peas in the concentration camp in Transnistria during the Second World War. Ultimately, they all became ill from Lathyrism.
Other conditions which are similar to lathyrism
– Konzo
– Lytico Bodig Disease
Progression of Lathyrism
Lathyrism begins weeks or months after consuming grass peas. It usually occurs in a setting of protein calorie malnutrition. The onset of disease may be acute, subacute or insidious. The early signs of the disease occur in the form of cramps in the calf muscles. Later, increased muscle tone, spasticity, brisk reflexes and Babinski’s signs occur. There is a typical absence of sensory loss. The gait is that of paraplegia in flexion and is characterized by slight flexion of hips and knees, retraction of tendon Achilles, adductor crossing and feet in plantar flexion.
Predominant neuropathological lesion – Ther occurs fibre loss in pyramidal tracts, mainly in the lumbar part of the cord along with pallor of fasciculi gracilis and axonal swelling in Goll’s nuclei.
The spastic paraparesis of lathyrism is associated with greatly increased tone in thigh extensors and adductors and gastrocnemius muscles. This leads to a lurching scissoring gait characterized by patients walking on the balls of their feet. Sensory signs are rare but they may be reported to occur in legs at the onset of the disease.
Classification of Neurological Deficit in Lathyrism
The neurological deficits in lathyrism are classified as –
1. No stick stage
2. 1 stick stage
3. Crawler stage
Neuro-lathyrism can be prevented by mixing grass pea preparations with cereals. Detoxification of grass peas can also be done through aqueous leaching.
Neuro-lathyrism Epidemics
Epidemics of neuro-lathyrism generally occur during times of food shortage which include situations of wars, flooding or drought. They are recorded to have occurred during the Spanish Civil War (1936-1939) in China, Bangladesh and India during the 1970’s and in Ethiopia during the 1970s and 1990s.
Symptoms of Lathyrism
The onset of neurological symptoms is usually sudden in lathyrism. The onset coincides with the monsoon season.
Below mentioned are the early symptoms of lathyrism –
– Difficulty in walking
– Severe and excruciating cramps
– Muscle weakness
– Weakness in the legs
– Increased tone
– Spastic paralysis which gradually becomes irreversible
– Hyperactive knee and ankle tendon reflexes
– Plantar extension response
– Scissoring gait
– Deformed body growth
Complications of Lathyrism
Below mentioned are the complications of lathyrism –
– Paralysis in the limbs (lower)
– Weakness in the lower limbs
– Tingling sensation and or numbness in the limbs
– Loss of vision
– Headache
– Loss of memory
– Loss of cognitive functions
– Behavioural problems
– Obsessive compulsive behaviour
– Imbalance
– Sexual dysfunction
– Problems related to circulation of blood
– Depression
– Flu-like symptoms
– Coma
– Death
Risk factors of Lathyrism
Below mentioned are the risk factors of lathyrism –
– Regular consumption of chickling pea flour
– Excessive consumption of boiled or raw chickling peas
– Living in drought or flooded areas
– Cooking foods in utensils made up of clay
– Eating grass pea in unripe and boiled form
– Belonging to O blood group
Diagnosis of Lathyrism
Currently there are no specific medical investigations or biomarkers which would help in diagnosis of lathyrism. Dietetic history will be the gamechanger. On the other hand, the other conditions shall be ruled out. Lathyrism is an irreversible condition and there are no known cures for an established lathyrism.
One should seek emergency medical care when the below mentioned signs and symptoms are evident –
– Muscle rigidity and spasms
– Weakness
– Paralysis of leg muscles
– Decreased breathing
– Weak heartbeat
– Seizures
Outlook
The outlook of lathyrism depends on the duration and level of exposure to the neurotoxins and also the severity of nerve injury. Many people recover fully after proper treatment. Some people survive in spite of not recovering completely. Some cases can be fatal.
Prevention of Lathyrism
Below mentioned are the best ways of preventing lathyrism from occurring –
– Avoiding consumption of foods prepared from seeds, flour etc of Lathyrus sativus or any of its variants, chickling flour and its other forms.
– Keeping away from consumption of grass pea / Lathyrus sativus. Some states in India have banned the selling of lathyrus seeds of lathyrus. This will prevent its consumption to a large extent.
– Detoxifying the seeds of Lathyrus sativus – by repeatedly boiling or soaking them in water and discarding their extract
– Roasting the seeds of Lathyrus – at 140 degree C for 15-20 minutes
– Soaking the seeds of Lathyrus – overnight and decanting the water before boiling them is said to remove about 90% of its toxins
– The risk of lathyrism can be reduced by consumption of grass pea with legumes having high concentration of sulphur based amino acids and antioxidants.
What can remove toxins from Lathyrus sativus?
Toxins can be removed by autoclaving the seeds of Lathyrus sativus with lime.
Treatment of Lathyrism
Though nor progressive, lathyrism is an irreversible disease. Spasticity of neuro-lathyrism has been shown to significantly reduce on using a centrally acting muscle relaxant Tolperisone. Apart from this, successful methods of managing this condition have not been found or documented and further studies to understand this illness are needed. The management is symptom based. To prevent the further aggravation of the symptoms is the key strategy and to achieve that, immediately stopping the consumption of anything derived or prepared from Lathyrus sativus or other variants of Lathyrus and immediate elimination of exposure to the toxin will need to be done.
Studies have shown complaints of walking difficulty due to weakness and leg stiffness, frequency of micturition, spastic gait, toe walking and use of walking sticks in those suffering from Lathyrism and who have consumed Lathyrus sativus regularly. In other studies, higher frequency of peripheral neuropathy and lower motor neuron involvement has been reported.
Study – Lathyrism induced myelopathy – Most of the clinical studies on lathyrism highlights the epidemiologic aspects of the study.
Study – Prevalence of Neuro-lathyrism and its associated factors in grass pea cultivation areas of Dawant district, Northh Eastern Ethiopia; 2022: a community based multilevel analysis showed – ‘The prevalence of neuro-lathyrism was found to be high. Ever feeding only grass pea, grass pea to other cereals mixing ration (using ratio of 1:1 or more) and ever feeding immature grass pea seeds were the modifiable risk factors for neuro-lathyrism.
Read here – other studies and works on lathyrism.
Lathyrism – Ayurveda Understanding
There is a condition called Kalaya Khanja explained in Ayurveda. This condition is closely correlated with Lathyrism. This is a condition wherein the person is a victim of Khanjatva – i.e. he is limping and the cause of the limp is excessive consumption of Kalaya – Lathyrus sativus or grass pea. Lathyrus sativus has qualities which are similar to those of vata and thus tends to aggravate vata to severe proportions. This vata on getting lodged in the pelvis, low back and lower limb, would afflict the nerves, bones, joints, muscles and connective tissues therein causing difficulty in walking and consequently making the person limp. Symptoms of Kalaya Khanja encompasses the symptoms of all three kinds of Lathyrism. Kalaya Khanja is explained in the context of Vata Vyadhi.
Related Reading – ‘Kalaya Khanja’
