Lathyrism: Causes, Symptoms, and Treatment

Introduction:

A neurotoxin is a toxin that destroys nerve tissue, causing neurotoxicity. Neurotoxins are a widespread class of exogenous chemicals, which cause neurological damage that can impair function in both developing and mature neural tissue. Neurotoxins are often neurologically destructive. Neurotoxins inhibit neuronal control through ionic concentrations across cell membranes or interneuronal communication across synapses. Treatment of neurotoxicity generally includes symptomatic and supportive care after eliminating or reducing exposure to toxic substances. The outlook depends on the duration and level of exposure and the severity of nerve injury. Many people make a full recovery after treatment. Some may survive but not fully recover. In other cases, exposure to neurotoxins can be fatal.

What Is Lathyrism?

Lathyrism, one of the oldest known neurotoxic diseases, results from overeating the chickpea (Lathyrus sativus) and certain related species. Once widespread in parts of Europe, North Africa, the Middle East, and south Asia, the disease is now confined to India, Bangladesh, and Ethiopia. Lathyrism is a type of irreversible, non-progressing spastic paraplegia (paralysis of legs) associated with poorly understood degenerative changes in the spinal cord. Pets, especially horses, also develop hind limb paralysis after eating sweet pea diets for a long period of time. There are three types of lathyrism. All of these are incurable, and the symptoms and body tissues affected vary.

• Neurolathyrism - Neurolathyrism is caused due to the consumption of large quantities of Lathyrus grain, specifically the grains in the genus that contain the glutamate analogue neurotoxin ODAP (oxalyldiaminopropionic acid). It is caused due to Lathyrus sativus (also called chickling pea, grass pea, kesari dal, or almorta), Lathyrus cicera, Lathyrus ochrus and Lathyrus clymenum.

• Osteolathyrism - Osteolathyrism affects connective tissue and bones, not the nervous system. This is a skeletal disorder caused by the toxin BAPN (beta-aminopropionitrile), which inhibits the copper-containing enzyme lysyl oxidase involved in the cross-linking of tropocollagen and proelastin. BAPN is also a metabolite of compounds found in sprouted seeds of peas, peas and lentils.

• Neurolathyrism - Neurolathyrism involves the collagen in blood capillaries. It is also caused by the toxin BAPN (beta-aminopropionitrile).

What Are the Causes of Lathyrism?

Lathyrism is a disease caused by eating the seeds of Lathyrus species (grass peas), mainly Lathyrus sativus (chickpeas or khesari), Lathyrus Cicera (common astragalus), and Lathyrus Clymenum (spanish astragalus). The disease affects horses and cattle as well as humans. Beta-oxalyl-amino-L-alanine acid (BOAA) is an excitatory neurotoxin and a glutamate agonist that has been identified as a disease-causing component of chickpeas. BOAA appears to exert its effects through mitochondrial toxicity (mitochondria is the powerhouse of a cell).

What Are the Risk Factors for Lathyrism?

The risk factors of lathyrism are listed below:

• Cooking food in clay utensils.

• Staying in a drought and flooded area.

• Consuming boiled or raw chickling peas in large quantities.

• Consuming chickling pea flour regularly.

• Eating peas in unripe and boiled form.

• Blood group O.

What Are the Symptoms of Lathyrism?

The onset of neurological symptoms of lathyrism is usually sudden and coincides with the monsoon season. Early symptoms include:

• Difficulty walking.

• Excruciating cramps.

• Weakness of the legs.

• Spastic paralysis develops and becomes irreversible.

• Muscle weakness.

• Increased tone.

• Scissoring gait is caused by the involvement of the extensor and adductor muscles of the thigh and the gastrocnemius.

• Plantar extension response.

• Hyperactive knee and ankle tendon reflexes.

• Deformed body growth.

When to Get Help for Lathyrism?

In case of the following signs and symptoms, the person is advised to seek emergency medical care:

• Muscle rigidity.

• Muscle spasms.

• Weakness.

• Paralysis of leg muscles.

• Weak heartbeat.

• Decreased breathing.

• Seizures.

How Is Lathyrism Diagnosed?

There are no specific medical investigations or biomarkers for lathyrism. A detailed history of the diet of the patient and the exclusion of other conditions is the hallmark methods of the diagnosis. Lathyrism is an irreversible illness for which there are no known cures once it is established.

What Is the Treatment of Lathyrism?

Lathyrism is usually not a progressive condition, but it is irreversible. Tolperisone, a centrally acting muscle relaxant, has been shown to significantly reduce spasticity (abnormal increase in muscle tone) in neurotic patients. Apart from that, due to the rare nature of this condition, not many methods of management have been found, and further studies are still required to gain deeper knowledge about this illness. The management of this condition is symptom based, and immediate elimination of exposure to the toxin can prevent further aggravation of the symptoms.

What Are the Complications of Lathyrism?

Lathyrism can lead to the following complications:

• Headache.

• Vision loss.

• Loss of memory and cognitive function.

• Paralysis or weakness in the limbs.

• Tingling and numbness in the limbs.

• Uncontrollable obsessive or compulsive behavior.

• Behavioral problems.

• Imbalance.

• Flu-like symptoms.

• Sexual dysfunction.

• Depression.

• Loss of circulation.

• Coma.

• Death.

How to Prevent Lathyrism?

• Boiling in water, soaking in hot water, and discarding the extract repeatedly can detoxify the seeds.

• Roasting the seeds at 140°C for 15 to 20 minutes results in 80 to 90 % neurotoxin accumulation.

• Soaking the seeds or dal overnight and decanting the water before boiling removes about 90 % of the toxins.

• Eat foods with antioxidants and a mixture of grains rich in sulfur amino acids.

• Avoid eating chickling flour and its other forms.

Conclusion:

Lathyrism is a chronic toxic tropical neuropathy caused due to long-term ingestion of drought-tolerant chickpea (Lathyrus sativus) flour. The disease is found in horses and cattle as well as humans. Beta-oxalyl-amino-L-alanine-acid (BOAA), an excitatory neurotoxin and glutamate agonist, is the disease-causing component of chickpeas. BOAA exerts its effects through mitochondrial toxicity. Avoiding the excessive use of chickling peas and their various forms in food may lead to the successful prevention of this condition. Proper cooking of the chickling peas may lead to the removal of their toxic properties.