Other causes of tremor other than essential tremor (ET) include enhanced physiologic tremor, which occurs when there is a systemic condition that affects the nervous system. physiologic tremor refers to the concept that there are muscles flexing and extending a given joint in alternation to maintain a particular posture. When viewed under a microscope, this oscillation can be seen in any of us. It’s normal, meaning physiologic. Under certain circumstances, this rhythmic movement may manifest as a visible tremor, called enhanced physiologic tremor.
Less common causes of tremor include orthostatic tremor, where the tremor is present upon standing, primarily in the legs, improving with walking. This is very rare. Dystonic tremor is an important cause of tremor in a body part such as the head/neck or an arm, and is associated with abnormal posturing. Cervical dystonia causing head tremor can be differentiated from head-predominant essential tremor in that it tends to cause a more irregular, multidirectional tremor, and often improves in one direction, and is associated with abnormal posture. Holmes’ tremor (rubral tremor) is very rare and causes a mixed postural, action and rest tremor due to a lesion in the red nucleus of the midbrain (part of the brainstem). This can be seen after stroke or traumatic brain injury and is very difficult to treat. Multiple sclerosis and other related conditions can cause a cerebellar tremor due to lesions in the cerebellum. This is associated with discoordination and inaccuracy of movements.
