Tremor

Description

The most common tremor disorder and is a low-amplitude, bilateral action and postural tremor with a frequency of 6-8 Hz. The tremor usually has its onset in adulthood and worsens over time, but it may begin in childhood and can coexist with other movement disorders. ET involves the upper limbs in more than 90% of patients. It less commonly involves the head, legs, or voice. Patients commonly first complain of difficulty with tasks requiring fine coordination, such as threading a needle, tying knots, or writing. Alcohol may temporarily alleviate symptoms, and family history is often positive. May be due to unstructural cerebellar dysfunction with ET patients commonly have an intention tremor and difficulty with tandem gait

Dystonic tremor is a jerky postural and task/action 3-8 Hz tremor that is abolished by complete rest and occurs in a body part affected by dystonia (e.g., limbs, trunk, head, vocal cords, or face). This contrasts with essential tremor in which the kinetic component is more or less constant throughout all postures. Dystonic tremor may occur with other involuntary movements including blepharospasm, torticollis, or spasmodic dysphonia. Isolated head tremor can be particularly challenging to distinguish between essential tremor and dystonic tremor (the latter of which can be exquisitely responsive to pharmacological treatment or botulinum toxin injections). The tremor caused by cervical dystonia is usually present as “no-no” kind of head shaking

Non-pathologic postural tremor, which typically has a frequency of 8-12 Hz. Both ET and physiologic tremor can be elicited by posture, both are fairly symmetrical, and both occur predominantly in the arms. Observing the progression of a tremor over time will often reveal whether a given patient has ET or physiologic tremor

Although predominantly an action tremor, Holmes tremor frequently has a significant resting component. The amplitude of movement tends to be large and it can sometimes adopt a “wing-beating” appearance. It is also among the slowest tremors, with frequencies often less than 4 Hz. It can occur with lesions affecting not only the red nucleus and rubral spinal tract in the brainstem but also the cerebellum and thalamus. The tremor may appear weeks to months after a known lesion (e.g., stroke), and some patients may have associated dystonia

Tremor may accompany diseases of the anterior horn cell (e.g., amyotrophic lateral sclerosis) and peripheral neuropathies. It is unclear whether tremor associated with peripheral neuropathy is due to enhanced physiologic tremor secondary to weakness, to an abnormality in the central nervous system, or both

The onset of tremor should be temporally related to drug ingestion and may be due to an enhancement of physiologic tremor (e.g., amiodarone, antidepressants, antiepileptic medications, beta-agonist bronchodilators, caffeine, lithium, neuroleptics, nicotine, steroids, and sympathomimetics) or production of cerebellar tremor (immunosuppressive agents and acute/chronic alcohol)

Clinical features suggesting psychogenic tremor include sudden onset with severe presentations, inconsistent combinations of resting and postural or kinetic tremor, entrainment (change in frequency of tremor to that of a task performed in another body part, e.g., a patient with left hand tremor who taps at various frequencies with the right hand will have a left hand that acquires those frequencies), and tremor that diminishes with distraction

A 4-9 Hz low-amplitude rest tremor, often with a “pill-rolling” quality. A typical pattern of spread is for the dominant hand to be affected first, followed by the dominant foot and then the non-dominant hand. Re-emergent tremor occurs while sustaining a prolonged position and most likely represents a rest tremor that has been reset by the relative stasis of a persistent position. Postural tremor that begins immediately on adopting a position is seen in as many as 93% of patients with PD and correlates with the degree of functional disability. Treatment with levodopa improves bradykinesia and rigidity more reliably than it does tremor

Cerebellar tremor is characterized as a jerky, low-frequency (2-5 Hz), high-amplitude action tremor. This tremor may be accompanied by other cerebellar signs such as ataxia, dysdiadochokinesia, dysarthria, dysmetria, and telegraphic speech

The character of the tremor depends on the region of the brain that is damaged. Damage to the brainstem may produce rest tremor if it affects the substantia nigra and related pathways. Damage to the cerebellum may result in a low-frequency action tremor. Because multiple regions are usually damaged, post-traumatic tremors are generally mixed in character. Post-traumatic tremor is often accompanied by myoclonus

Uncommon condition that starts in late adulthood with feeling of tremulousness in the legs when standing (but not sitting or lying). The diagnosis is helped by specific surface EMG showing a 14-18-Hz oscillating tremor in the musculature of the legs when standing, disappearing with rest or movement

A rare disorder presenting as unilateral or bilateral rhythmic involuntary movements of the soft palate. The movement consists of repetitive rather than oscillatory movements of agonist muscles only, thus having some similarity with myoclonus. The tremors in essential palatal tremor produce audible click due to the contraction of the tensor veli palatini muscle which disappear during sleep, whereas in symptomatic palatal tremor there is no audible click but it continues during sleep

DBS

Expensive

Hardware maintenance

Longer surgery

Habituation

Reversible to some degree

More forgiving if got wrong

Staged bilateral (VIM)

Other targets (bilateral)