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Clonus Causes

Clonus Causes

Involuntary and recurring contractions of the muscles, when they are stretched, is known as clonus. It is generally related to a neurological disorder. Elucidated in this article, are a few neurological disorders which might lead to clonus.
Chandramita Bora
Last Updated: Apr 8, 2018
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Is your body acting up, and having reflexes that you aren't able to control? This can be termed as 'clonus', the Greek meaning for involuntary, violent, and confused motion.

Clonus refers to involuntary, rhythmic, and repetitive muscular contractions, that usually occur in the ankles, wrists, and the kneecaps or patellas. The ankles are the most commonly affected area by clonus. This can be explained as a deep tendon reflex, that stems from the abnormality in neuromuscular activity. It generally occurs when the muscles are stretched, and can be observed in the ankles when the foot is jerked upwards at the ankle, or while trying to hold the joint muscles still. It is generally associated with neurological problems.

What May Lead to Clonus?

Multiple Sclerosis (MS)

This is a progressive chronic autoimmune nervous disorder that is characterized by loss of myelin sheath around the nerve fibers, which disrupts the communication between the brain and the spinal cord. This in turn affects movement, sensation, and bodily functions.


Meningitis is a bacterial infection or inflammation of the meninges that surrounds the brain and spinal cord, and is often characterized by vomiting, severe headache, fever, stiffness in the neck area, and muscle contraction.

Huntington's Disease

This is an uncommon hereditary neurodegenerative disorder, which leads to progressive jerky muscle movements (chorea), and can affect normal muscle coordination, as well as cause mental deterioration. These symptoms might eventually lead to dementia, and there is no effective treatment for the same as yet.

Spinal Cord Injury

Any injury that damages the spinal cord may lead to myelopathy (myelinated fiber tracts that carry signals to and fro from the brain, gets damaged). This might also lead to loss of sensation and motor control.


It is an unnatural condition in pregnancy, which is characterized by fluid retention, high blood pressure, and proteinuria. This condition, if left untreated, might lead to eclampsia (toxic condition along with convulsions).

Cerebral Palsy

This condition is a non-progressive movement and posture disorder caused by abnormal development of the motor control centers of the brain. The abnormalities of muscles that determine cerebral palsy are mostly followed with a few other physical and neurological abnormalities.

Creutzfeldt-Jakob Disease

Pronounced as 'kroits-felt yah-kohb', this is a rare fatal malady of the brain, which is characterized by progressive dementia. This disease mostly occurs during middle age, and is caused by an unidentified and slow virus. A patient gradually loses control over his muscles.

Upper Motor Neuron Lesion

These are the motor neurons that arise from the motor region of the cerebral cortex. Motor neurons are basically concerned with carrying impulses from the brain and spinal cord. Any damage to the nerve tract, particularly between the brain and the level at which the peripheral nerves come out of the spinal cord, can cause clonus.

Stroke (Cerebrovascular Accident)

This is an abrupt and sudden loss of brain function due to the rupture or closure of a blood vessel in the brain, which would result in necrosis of the brain tissues. This eventually leads to loss of muscle control, dizziness, etc.

Spastic Paraparesis

This condition leads to a mild loss of motor function, along with spasms and weakness in various parts of the body. It is a clear indication of central nervous system disorders which are the reason for the injury to the motor cortex or descending motor pathways.

Subacute Sclerosing Panencephalitis

An abnormal immune reaction to the measles virus leads to this rare and fatal progressive brain disorder. It occurs more commonly in children, and shows symptoms like myoclonic seizures, progressive impairment of mental and motor functioning, behavioral changes, etc.

Brown-Séquard Syndrome

This condition is a loss of motor function (ataxia) and sensation (paralysis), which is caused by the lateral cutting of the spinal cord.

Diagnostic Options

As the above-mentioned causes indicate some serious neurological problems, a neurologist would perform the following tests of the spinal cord, brain, and the brain stem, in order to detect the underlying cause(s).

❒ Computerized Tomography (CT Scan)
❒ Magnetic Resonance Imaging (MRI)
❒ Cerebrospinal Fluid (CSF) Analysis
❒ Myelography (radiography using X-ray of the spinal cord to detect any lesions)

The treatment would be guided by the results of these tests or the determination of the exact cause. Therefore, early diagnosis plays an important role in identifying the underlying neurological problems and their timely treatment.

Disclaimer: This article is purely for informative purposes, and should not be used as a replacement for professional medical advice.