Clonus Causes

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

What Causes Clonus?
As has been mentioned already, clonus is related with neurological problems or disorders. It is often considered as a sign of several health conditions, related to the nervous system. Lesions in the upper motor neurons are the most common cause of clonus. 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.

Clonus is generally originates in the spinal cord, especially if both the legs are affected. It can be a sign of neurological disorders like multiple sclerosis, spinal cord damage, stroke and hepatic encephalopathy, which are associated with upper motor neuron lesions. Multiple sclerosis is a progressive 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. Therefore, it can lead to clonus. Likewise, stenosis or tightening of the spinal cord, which is the case with disc diseases, can lead to clonus including ankle clonus. Read about nervous system.

Spastic paraparesis is a condition, associated with spasms and weakness in various parts of the body and it can also can lead to clonus. Another common cause of clonus is epilepsy, which is a disorder of the central nervous system. Apart from these, some rare clonus causes are Huntington's disease, meningitis (bacterial infection or inflammation of the meninges that surrounds the brain and spinal cord), Brown-Sequard Syndrome and Creutzfeldt-Jakob disease. Huntington's disease is a neurodegenerative disorder, that can affect normal muscle coordination, while Brown-Sequard Syndrome is related to spinal injury and can affect motor functions. On the other hand, Creutzfeldt-Jakob disease is a very rare condition, where the sufferer gradually loses control over his or her muscles. It is caused by an unidentified virus. If clonus appears after taking serotonergic drugs, then it can indicate impending serotonin syndrome, which is basically a type of drug reaction.

As clonus indicates some serious neurological problems, a neurologist would perform several tests like CT scan and magnetic resonance imaging or MRI of the spinal cord, brain and the brain stem, in order to detect the underlying causes of clonus. For detecting spinal cord lesions, X-ray of the spine and spinal fluid analysis are performed. It may also require other tests like myelography. The treatment for clonus would be guided by the results of these tests or the determination of the exact clonus causes. Therefore, early diagnosis plays an important role in identifying the underlying neurological problems and their timely treatment.