This happens to me a lot, if I m sitting in a certain position, and I press down on my foot, my leg starts shaking, and I have difficulty stopping it. It s not only while sitting down though, you can do it standing up. It s not 100%
uncontrollable, but sometimes it can be tricky to stop. EDIT: THE ANSWER IS HERE THANKS TO Physiotherapist here, OP need not worry, those who are relating this to clonus are partially correct- it is a reflex response, but not a clonus reflex. Clonus is a sign of neurological damage, namely upper motor neurone lesions. Putting your foot on its tiptoes won t give you an upper motor neurone lesion thankfully! It s part of the Golgi tendon reflex. Golgi tendons are small receptors located in every muscle that protect them from over stretching damage. They do this by recognising when a muscle is over stretched and then sending a message to your spinal cord- which then sends a message back telling the muscle to contract to prevent it hurting itself.
When OP goes up onto his tiptoes the Golgi tendons sense his calf (gastrocnemius, soleus and to a lesser degree plantar is) is stretching, so the it sends the message to the spinal cord and we get the contraction reflex. So then his leg rises due to plantar flexion at the ankle and the calf muscles relax. After they relax, his leg drops again- we get the stretch- then the stretch reflex and the cycle repeats, carrying on the continual bounce of his leg, which usually wobbles the dinner table and cause his sister to spill gravy everywhere! Hope this makes sense! TL; DR not clonus, Golgi tendons. In addition to type, tremors are also classified by their appearance and cause. Essential tremor is the most common type of movement disorder.
Essential tremors are usually postural or intention tremors. An essential tremor may be mild and not progress, or it may slowly progress. If the essential tremor progresses, it often starts on one side and then affects both sides within a few years. Essential tremors werenвt thought to be associated with any disease processes. However, recent studies have connected them to mild degeneration in the cerebellum, which is the part of the brain that controls motor movement. Essential tremors are sometimes associated with mild walking difficulty and hearing disability, and they tend to run in families. AВ Parkinsonian tremorВ is usually a resting tremor and is often the first sign of Parkinsonвs disease. Itвs caused by damage to parts of the brain that control movement. The onset is usually after age 60. It begins in one limb or on one side of the body, and then it progresses to the other side.
A dystonic tremorВ occurs irregularly. Complete rest can relieve these tremors. This tremor occurs in people who have dystonia, which is a movement disorder characterized by involuntary muscle contractions. The muscle contractions cause twisting and repetitive motions or abnormal postures, such as twisting of the neck. These can occur at any age. The cerebellum is the part of the hindbrain that controls movement and balance. A В cerebellar tremorВ is a type of intention tremor caused by lesions or damage to the cerebellum from a stroke, tumor, or disease, such as multiple sclerosis. It may also be the result of chronic alcoholism or overuse of certain medications. A В psychogenic tremorВ may present as any of the tremor types. Itвs characterized by sudden onset and remission, changes in the direction of your tremor and the affected body part, and greatly decreased activity when youвre distracted.
Patients with psychogenic tremors often have conversion disorder (a psychological condition that produces physical symptoms) or another psychiatric disease. An orthostatic tremorВ usually occurs in the legs. This is a rapid, rhythmic muscle contraction that occurs immediately after you stand. This tremor is often perceived as unsteadiness. There are no other clinical signs or symptoms. The unsteadiness stops when you sit, are lifted, or when you start walking. A physiologic tremorВ is often caused by a reaction to certain drugs, alcohol withdrawal, or medical conditions, such as hypoglycemia (low blood sugar) or an overactive thyroid gland. Physiologic tremor usually goes away if you eliminate the cause.