Clonus vs. Myoclonus — What's the Difference?

Clonus is a neurological condition characterized by involuntary and rhythmic muscle contractions that typically indicate an underlying health issue, often related to a lesion in the nerve pathway. These contractions can be sustained or repetitive and are usually provoked by a sudden muscle stretch. Whereas myoclonus consists of sudden, brief, involuntary muscle jerks or twitches, which can be symptomatic of various neurological disorders but may also occur in healthy individuals without any pathological significance.

While clonus is often associated with conditions such as multiple sclerosis, stroke, or spinal cord injury and can be seen in certain areas of the body like the ankles or knees, myoclonus may be observed as a result of sleep, as in hypnic jerks, or in association with a wider range of conditions including epilepsy, Alzheimer’s disease, or even as a reaction to medication. This distinction highlights the differing clinical contexts and potential underlying causes of each condition.

The rhythmic nature of clonus distinguishes it from the sporadic and unpredictable jerks of myoclonus. This rhythmic pattern in clonus can sometimes help in diagnosing the severity and the type of underlying neurological damage, while the varied presentation of myoclonus requires a broad diagnostic approach to determine its cause and significance.

The management and treatment of clonus often involve addressing the underlying cause, if identifiable, and may include physical therapy, medications, or other interventions aimed at reducing muscle tension and improving motor control. On the other hand, the treatment of myoclonus focuses on the specific type of myoclonic jerks present and may involve medications such as anticonvulsants, if the jerks are epileptic in nature, or other treatments tailored to the underlying cause.

In terms of prognosis, clonus often reflects the presence of a significant neurological disorder, and its management largely depends on the ability to treat the underlying condition. Myoclonus, however, can vary widely in its implications, from benign phenomena requiring no treatment to symptoms of serious neurological diseases that may need comprehensive management strategies.