Involuntary Movements and Tremor Diagnosis

Involuntary movements compose a group of uncontrolled movements that may manifest as a tremor, tic, myoclonic jerk, chorea, athetosis, dystonia or hemiballism. 

Recognition of involuntary movements associated with hyperkinetic movement disorders is an important diagnostic skill. This page describes the diagnosis of the major categories of hyperkinetic movement disorders.

General Definitions

1. Tremor: Rhythmic oscillations caused by intermittent muscle contractions.
2. Tics: Paroxysmal, stereotyped muscle contractions, commonly suppressible, might be simple (single muscle group) or complex. Temporarily suppressible.
3. Myoclonus: Shock-like, arrhythmic twitches. Not suppressible.
4. Chorea: Dance-like, unpatterned movements, often approximate a purpose (e.g. adjusting clothes, checking a watch). Often rapid and may involve proximal or distal muscle groups.
5. Athetosis: Writhing movements, mostly of arms and hands. Often slow.
6. Dystonia: Sustained or repetitious muscular contractions, often produces abnormal posture.
7. Hemiballismus: wild, large-amplitude, flinging movements on one side of the body, commonly affecting proximal limb muscles but can also affect the trunk.

Physiologic Tremor

1. Present in almost everyone and a normal finding that usually cannot be seen unless worsened in certain situations that include:
   1. anxiety, fear, physical exhaustion, hypoglycemia, hyperthyroidism, alcohol withdrawal

"Essential" Tremor (ET) (Kinetic Tremor / Familial Tremor)

1. Most common involuntary movement disorder, typified by a rapid postural tremor most often of the upper extremities.
2. Progressive, may appear at anytime of life but most commonly >70 years.
3. Mainly a postural tremor but if worsened, will occur at rest
4. Commonly bilateral and symmetric.
5. Classically affects head and/or speech.
6. Classically, tremor decreases with EtOH, worsens with stress.
7. Neurological exam is otherwise normal.
   1. Differentiate from Parkinson by noting absence of resting tremor, rigidity, bradykinesia, etc.

Intention Tremor ( Cerebellar Tremor)

1. Slow action tremor that most commonly occurs with purposeful movement (such as in doing finger to nose test)
2. Usually associated with other cerebellar findings
3. Seen in any process that causes damage to the cerebrellum (stroke, tumor, multiple sclerosis, chronic alcohol abuse, certain medications)
4. Unlike the cerebrum, cerebellar disease causes problems on the SAME SIDE of the body as the the cerebellar lesion
5. Titubation refers to tremor of the head (and sometimes trunk) due to cerebellar disease

Parkinsonian Tremor

1. Most common cause of a resting tremor that usually involves the distal muscles (e.g. pill rolling tremor of the hand)
2. May decrease with voluntary activity (e.g. raising arm) and increase with mental activity (e.g. asking patient to do math) and increase with anxiety or emotional excitement
3. Causes:
   1. Idiopathic parkinson's disease: usually starts in one hand then spreads to other limbs
   2. Drugs: antipsychotic agents, metoclopramide, prochloperazine
   3. Encephalitis (HIV/AIDS, neurosyphilis, PML, toxoplasmosis)
   4. Chronic head trauma
4. Note: other resting tremors include Wilson's Disease and severe essential tremor (ET is usually postural but when servere can be seen at rest or even with movement)

Myoclonus may be benign (as in hypnopompic and hypnagogic jerks) or disabling. Myoclonic jerks may occur with voluntary movement (action myoclonus) or as a result of a stimulus (startle or reflex myoclonus). Unlike tics, myoclonus is not suppressible. Myoclonus is often associated with CNS pathology, hypoxic damage (e.g. during cardiac arrest), neurodegenerative disorders, and encephalopathy.

1. Physiologic myoclonus is often normal in people, for example myoclonic jerks during sleep transitions.
2. Epileptic myoclonus referred to myoclonus in the setting of epilepsy.
3. Essential myoclonus is a familial condition typified by multifocal jerks, usually benign.
4. Symptomatic (secondary) myoclonus refers to myoclonus that occurs secondary to neurodegenerative diseases such as alzheimer's disease, Huntington disease, Lewy body dementia and Creutzfeldt-Jacob disease.
5. Negative myoclonus is the term sometimes used to contrast myoclonus. It represents short periods of loss of muscle tone most commonly seen in liver disease patients with hepatic encephalopathy. Is can also be seen in severe uremia and certain toxins (sometimes referred to as reversible myoclonus).

Huntington's Disease

Huntington's chorea is arrhythmic, nonrepetitive, semi-purposeful and involves the limbs, trunk, and face. Early manifestations are mild and may be unnoticed or attributed to restlessness. Motor impersistence (e.g. inability to sustain tongue protrusion) is a common feature. See the Abnormal Gaits Page for description and demonstration of the Choriform gate.

Other Choreas

1. Sydenham's chorea (aka Saint Vitus Dance) is one of the major diagostic criteria for Rheumatic fever seen in prior Group A Streptococcal infection. It is most common among female patients, 5-15 years old. Rare in the US but more common in developing countries.
   1. Acute onset, choreiform movements, extreme restlessness.
   2. Most often self-limited.
   3. May reoccur, especially in pregnancy (chorea gravidarum).
2. Neuroacanthocytosis is a rare, recessive, relentlessly progressive disorder typified by chorea coupled with erythrocyte abnormalities and possibly dystonia, tics, seizures, polyneuropathy, and self mutilation. May present at any time in life.
   1. Similar presentation is noted in McLeod syndrome - an X-linked disorder associated with reactivity to Kell antigens, typically older patients.
3. Paroxysmal chorea has been described in hyper- and hypoglycemia, vascular diseases, and infections.
4. Benign senile chorea & benign inherited chorea of childhood have been described but are controversial. It is important to rule out HD.
5. SLE and less commonly other autoimmune disorders may cause chorea.

Tourette's Syndrome (TS) is a neurobehavioral disorder predominately affecting males and typified by multiple motor tics and vocalizations. Such tics may be repressed for short periods of time or even become absent for days to weeks. Onset is most common before the age of 15 years and often lessens or even resolves in adulthood. TS is associated with anxiety, depression, ADHD, and OCD. Adult onset is associated with several medical conditions such as Parkinson's Disease, dystonia, drugs (e.g. neuroleptics, levodopa), and trauma.

Dystonia exists in a broad spectrum from a contraction of a single muscle group to a disabling dysfunction of multiple groups. Commonly, dystonia is initiated by voluntary motion (action dystonia) but may later become sustained and extend to other body regions. Classically, stress or fatigue worsen dystonia, relaxation or sensory stimulation reduce it.

Primary Dystonias

1. Idiopathic Torsion Dystonia (ITD), or Oppenheim's dystonia, is an autosomal dominant condition of variable penetrance seen most commonly in juvenile patients of Ashkenazi Jewish descent. Commonly, onset begins in foot or arm before progressing to other limbs, head, and neck.
2. Dopa Responsive Dystonia (DRD) is an autosomal dominant condition with an onset before 12 years of age that responds to levodopa.

Focal Dystonias

This is the most common type of dystonia, commonly presenting in the 4th to 6th decade of life, affecting females more than males. Frequently misdiagnosed as psychiatric or orthopedic conditions.

1. Blepharospasm: abnormal contraction of eyelids, increased blinking can affect ADLs.
2. Oromandibular dystonia (OMD): dystonic contractions of muscle groups of the jaw, tongue, lips, or lower face.
   1. Oral facial dystonia commonly affects women > 60 years old with both OMD and blepharospasm.
3. Cervical dystonia: dystonic neck muscle contraction, sometimes painful. May deviate head laterally (torticollis), anteriorly (anterocollis), or posteriorly (retrocollis). Sometimes associated with dystonic tremor and secondary cervical radiculopathy.
4. Spasmodic dysphonia: dysfunctional contractions of the vocal cords.
5. Limb dystonias: may present in either upper or lower extremities, often initiated by specific actions such as writing (writer's cramp) or laying a musical instrument (musician's dystonia).

Secondary Dystonias

Most commonly caused by medications (see below), brain lesions, or brainstem pathology. Most such dystonias are segmental in distribution. Less commonly, peripheral nerve injury may cause dystonia.

Dystonic Storm

Dystonic storm is an acute, generalized dystonic contraction that may include vocal cords or laryngeal muscles, leading to potentially fatal respiratory obstruction. Patients with a history of dystonia and subject to acute stress (such as surgery) are in jeopardy. Potential complications include rhabdomyolysis and renal failure. Dystonic storm is best managed in the ICU.

Acute

1. Most acute hyperkinetic drug reactions result in dystonia, typically generalized in children and focal in adults.
2. Amphetamines, methylphenidate, and cocaine are known to cause chorea, tics, and stereotyped behaviors.

Subacute

1. Most subacute reactions result in akathisia.

Tardive Syndromes

1. Tardive dyskinesia (TD) most often develops months to years after antipsychotic treatment is initiated. Most often, TD presents with choriform movements of the mouth, tongue, and lips.
   1. Lower risk of TD is conferred by youth and use of atypical antipsychotics. Increased risk is conferred by advanced age, toothlessness, and organic cerebral dysfunction.
   2. Roughly one third of TD cases resolve within 3 months of discontinuing the offending drug. Most other patients slowly improve over a course of years.
2. Tardive dystonia is associated with chronic neuroleptic exposure and is typified by axial muscle involvement and a characteristic rocking motion. Tardive dystonia often persists after offending medication is discontinued and is refractory to therapy.
3. Tardive akathisia and Tardive Tourette's syndrome are much less common but still associated with chronic antipsychotic exposure.

Neuroleptic malignant syndrome (NMS) is typified by rigidity, hyperthermia, AMS, tachycardia, and renal failure. Onset usually occurs days to weeks after exposure to medication. It might also be precipitated by discontinuation of antiparkinsonian medications.

Other drugs associated with hyperkinetic movement disorders include phenytoin, carbamazepine, TCAs, fluoxetine, oral contraceptives, buspirone, digoxin, cimetidien, diazoxide, lithium, methadone, and fentanyl.

Psychogenic movement disorders are common and may mimic any of the conditions described above. Affected patients are most often female and debilitated by their condition. Particularly somatoform, conversion disorder, malingering, and factitious disorder are associated with psychogenic movements.

1. Clinical features suggestive of a psychogenic cause:
   1. Acute onset.
   2. Movement patterns inconsistent with known movement disorder.
   3. Variability of movements (often increasing with attention) and distractibility from movements (often decreasing when patient is asked to perform another task).
   4. Many organic movement disorders commonly worsen when patient is distracted and improve with attention.
   5. Upper limb tremor is most commonly psychogenic.
   6. Variable tremor frequency is consistent with a psychogenic cause.
   7. If patient is asked to tap with one hand and the other hand's tremor entrains with the tapping, suspect a psychogenic cause.
2. Diagnosis is made based on the above in conjunction with failure to find an organic disease process