EM guidemap - Tremor

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Introduction

Clinical evaluation and decision-making

Appendix

Introduction and general principles

- this guidemap is designed to help an emergency physician differentiate the common types of tremor

Definition: A tremor is a rhythmical, involuntary oscillatory movement of a body part that involves alternating or synchronous contractions of reciprocally innervated agonistic and antagonistic muscles

- a tremor occurs at different frequencies, and can be seen at rest and/or during action

- all true tremors usually disappear, or are markedly reduced, during sleep

- a tremor is classified according to the position that creates its maximal frequency, but it can often be seen in more than one position eg. at rest, during postural changes, or during voluntary goal-directed actions

- action tremors occur when the muscle is actively contracting, and they include postural tremors, kinetic (intention) tremors, and isometric tremors

- the 3 major types of tremor are:- postural, rest and kinetic

Postural tremor

The tremor is maximised when the patient assumes and maintains a posture against gravity

- occurs at a frequency of 8 - 12 Hz

- may occur during movement and when holding an assumed posture against gravity

- relatively stable throughout a movement without exacerbation at the beginning or end of a task

- physiologic tremor is the most common non-pathological tremor, and it is usually asymptomatic and rarely visible, and usually most apparent in the upper extremities

- the tremor can be seen using "amplification" (such as holding a piece of paper on the outstretched hand or when pointing a hand-held laser pointer at a distant screen)

- the tremor may result from peripheral beta-sympathetic stimulation, and beta-blockers diminish the tremor

- an "enhanced" physiologic tremor is a visible postural tremor unaccompanied by neurological disease, and it occurs when a physiologic tremor is enhanced by emotional states, exercise, fatigue, withdrawal from alcohol or sedative agents, metabolic states (hyperthyroidism, hypoglycemia, pheochromocytoma, uremia, hypocalcemia, hypomagnesemia) or drugs
 

Drugs that can exacerbate a physiologic tremor

alcohol, anticonvulsants, amphetamines, arsenic, beta-sympathomimetic agents, bismuth, butyrophenones, caffeine, carbon monoxide, dopamine agonists, epinephrine. fluoxetine, haloperidol, heavy metals, hypoglycemic agents, lead, levodopa, lithium, mercury, methylbromide, methylphenidate, metoclopromide, monosodium glutamate, neuroleptics, phenothiazines, phenylpropanolamine, pseudoephedrine steroids, terbutaline sulfate, theophylline, thyroid hormones, tricylic antidepressants, valproic acid

Because an "enhanced" physiologic tremor is the most common cause of a postural action tremor, one should search for medical diseases causing tremor-enhancement, rather than a primary neurological disease

- the "enhanced" physiologic tremor disappears on elimination of the enhancing factor

- as there are no biomarkers to differentiate physiologic tremor from essential tremor, a visible postural tremor of the upper extremities in the absence of identifiable enhancing factors is currently classified as an essential tremor

- an essential tremor is the most common pathological cause of a postural tremor
 

 Characteristics of essential tremor
  • familial in 50% of cases, sporadic in the rest of the cases
  • usually starts when patients are in their adolesence or 30 - 40's, progresses with age, remains a life-long illness
  • tremor may be asymmetric and transient initially
  • established tremors are often bilateral and symmetric and mainly postural
  • tremor frequency of 4 - 12Hz; tremor frequency increases with time
  • a kinetic component is common and the tremor is accentuated with movement and the assumption of a posture; a rest component is less frequent; tremor disappears during sleep
  • usually involves the upper limbs (90%), and rarely the head (50%), neck, chin (15%) or voice (30%) - causing a shaky, wavering voice
  • tremor amplitude may transiently worsen with stress, fatigue, sexual arousal, CNS stimulation, or exposure to extreme temperatures
  • tremor amplitude can also worsen with goal-directed activities requiring precise movements eg. drinking from a cup, writing
  • monosymptomatic, with no other abnormal neurological signs other than occasional tandem gait difficulties
  • aggravated by certain nor-adrenergic medications
  • may be temporarily relieved by relaxation, mental concentration, or alcohol => possible rebound when alcohol wears-off
  • one first needs to exclude other causes of postural tremor due to metabolic disturbances or medications before diagnosing essential tremor

- the core criteria for an essential tremor are:- bilateral action tremor of the hands and forearms in the absence of other neurological signs other than "cog-wheeling" (an oscillation of resistance during passive movement thought due to be due to the tremor) and tandem gait disturbances

- secondary criteria include:- long duration (> 3 years), positive family history and beneficial response to alcohol

- signs that suggest a disorder other than essential tremor include:- unilateral tremor; isolated chin or voice or leg tremors; combination of rigidity, bradykinesia, rest tremor (suggests Parkinson's disease); sudden onset or step-wise progression (suggests stroke, MS or psychogenic etiology); gait abnormalities (suggests MS, stroke or Parkinson's disease) and the presence of enhancing drugs (suggests an "enhanced" physiologic tremor)

Rest tremor

Occurs when a limb is in maximal repose, and supported against gravity, so that the limb muscles are not actively contracting

- usually involves the upper limbs, and often the distal limb - thumb abducts-adducts and fingers flex-extend and the forearm supinates-pronates producing a "pill-rolling" movement

- frequency of 3 - 7Hz

- the most common cause of rest tremor is Parkinson's disease, which is suggested by an asymmetrical tremor and associated bradykinesia, rigidity and postural instability (the tremor may precede the other neurological signs; the tremor often disappears, or markedly lessens, with voluntary movement or mental concentration)

- even the most severe rest tremor, due to Parkinsons disease, disappears during finger-nose testing

- the tremor may spread to the legs, face and chin, but Parkinson's disease does not cause a head tremor (head titubation)

- other common causes of rest tremor include Parkinsons plus syndromes, medications having extra-pyramidal side-effects (neuroleptics, reserpine, metoclopromide, perhexiline, tetrabenazine), Wilson's disease, non-Wilsonian hepatocerebellar degeneration, midbrain pathology secondary to stroke or demyelinating disease, carbon monoxide poisoning, and heavy metal poisoning

Kinetic (intention) tremor

The tremor only occurs during action and is accentuated with voluntary movements

- the slow (2 - 5 Hz) tremor may show marked irregularity due to varying tremor amplitude during an action => the tremor may worsen when approaching the endpoint of a visually guided, goal-directed movement (intention tremor)

(* the tremor is side-to-side, and opposite to the main direction of the intended movement; the kinetic tremor paradoxically worsens when done under visual guidance, in comparison to when the same movement is performed with proprioceptive cues alone)

- the most common cause of a kinetic intention tremor is cerebellar disease (eg. MS or cerebellar infarction or cerebellar degenerative diseases), or a chronic relapsing polyneuropathy

- less common causes of tremor include:-  isometric tremor, which is evoked by voluntary isometric muscle contractions without movement eg. clenching a fist, holding up a weight, pushing hands against a wall; and a task-specific tremor, which only occurs during performance of a specific task
 
Clinical evaluation and decision-making

The main purpose of the clinical evaluation is to determine whether the tremor mainly occurs at rest, or mainly occurs during the adoption of a posture, or mainly occurs during voluntary action

The accurate classification of a tremor as a rest tremor, or postural tremor, or intention tremor will probably suggest the likely etiology

- first observe the patient at rest, with his arms supported against gravity in his lap to determine whether a rest tremor is present

- if a rest tremor is present => check for other signs of Parkinsons disease (bradykinesia, rigidity, gait difficulties)

(* see the appendix for a brief synopsis of Parkinsons disease)

- then ask the patient to lift his arms upwards with palms facing-up, and observe for any postural tremors => ask the patient to turn his palms down and observe for any postural tremor => ask the patient to move his elbows out into a "wing beating" position, so that the opposing fingertips are facing each other, and observe for postural tremors

(* rest tremors may re-appear after the action is completed and the adopted posture is passively supported against gravity, but the tremors should be less prominent during the action)

- then check for intention tremors of the upper limb during finger-nose pointing, and intention tremors of the lower limbs by heel-knee testing

- an action tremor that is much worse at the very end of a goal-directed movement (after a new posture is adopted) suggests an essential tremor (postural tremor), while cerebellar intention tremors produce steadily increasing oscillations before the target is even reached, and the tremor is usually at its worst before the end of a goal-directed movement is reached

- if an intention tremor is present => check for other signs of cerebellar disease eg. dysarthria, dysmetria, dyssynergia, dysdiadochokinesis, nystagmus, ataxia and hypotonia

(* cerebellar tremors are usually bilateral and symmetric, and often involve the proximal limb producing coarse tremors; an unilateral cerebellar tremor suggests unilateral cerebellar infarction or tumor)

- if a patient complains of leg tremors suggestive of orthostatic tremor (variant of essential tremor) => ask the patient to stand and palpate the thighs for quivering (which may be palpable and not visible) => ask the patient to walk, which is usually not a problem (in contrast to patients with cerebellar tremors affecting the lower limbs, which are often associated with ataxia)

(* see the appendix for more features of orthostatic tremors)

- check for head tremors (horizontal "no-no", or vertical "yes-yes"), which suggests an essential tremor in the absence of cerebellar signs

- finally, check for task-related tremors eg. lifting a cup, writing, drinking, eating

(* many tremors are worse during writing, but a tremor that is only present during writing suggests a primary writing tremor disorder)

- if the tremor mainly occurs at rest and is asymmetric with no other abnormal neurological signs => suggests early Parkinson's disease

- if the tremor is postural, first consider metabolic conditions or drugs causing an "enhanced"physiologic" tremor, before diagnosing essential tremor

- if the tremor is present both at rest and on adopting a posture, look carefully for evidence of bradykinesia or micrographia, which suggests Parkinson's disease (rather than an essential tremor)

- other clinical clues relate to tremor frequency

- tremor amplitude may also be a helpful clue - certain features suggest a psychogenic tremor - routine laboratory testing to r/o Wilson's disease or an endocrinopathy (hypoglycemia or hyperthyroidism or pheochromocytoma or hypoparathyroidism) is rarely necessary
 
Appendix

 
Postural tremor due to metabolic disturbances or drugs
 Metabolic disturbances
  • hyperthyroidism
  • hyperparathyroidism
  • withdrawal from alcohol or drugs
  • Wilson's disease
  • vitamin B12 deficiency
  • renal failure
  • pheochromocytoma
 Medications
  • beta agonists
  • theophylline
  • sodium valproate
  • tricyclic antidepressants
  • lithium
  • selective serotonin reuptake inhibitors (SSRIs)
  • steroids
  • cyclosporin and other immunosuppressants
  • dopamine agonists
  • metoclopromide
  • amiodarone
  • oral contraceptives
  • thyroid hormone
 Drugs
  • cocaine
  • caffeine
  • amphetamines
  • nicotine
  • stimulants

 
Classification and differential diagnosis of tremors
 Rest tremors
  • Parkinsons disease
  • other Parkinsonian syndromes (less common)
  • rubral tremor (rest < postural < kinetic)
  • Wilsons disease
  • essential tremor (only if severe, rest << postural or action) 
 Postural tremors
  • physiologic tremor
  • "enhanced" physiologic tremor
  • essential tremor
  • task-specific tremor
  • due to CNS disorders (parkinson's disease, other akinetic rigidity syndromes, idiopathic dystonia, rubral tremor)
  • due to peripheral neuropathy (Charcot-Marie Tooth syndrome, diabetes, recovery phase of Guillane-Barre, porphyria, IgM dysgammaglobulinemias)
  • Wilson's disease
 Kinetic (intention) tremor
  • cerebellar disease (MS, infarction, drugs, toxins, degenerative disorders)
  • chronic relapsing polyneuropathy
  • Wilson's disease
  • rubral tremor
 Miscellaneous rhythmical disorders
  • psychogenic tremor
  • orthostatic tremor
  • dystonic tremor
  • rhythmical segmental myoclonus
  • oscillatory myoclonus
  • asterixis
  • clonus
  • epilepsia partialis continua
  • hereditary chin quivering
  • spasmus nutans
  • head bobbing with 3rd ventricular cysts

Orthostatic tremor

- the tremor involves the trunk and lower limbs and only occurs when standing

- when asked to stand in one place, the patient develops hard cramping calves and thighs and shakes uncontrollably

- lifting the patient off the ground abolishes the tremor

- the patient can usually walk normally with only mild discomfort, and trembling disappears from the non-weight bearing leg during ambulation

- standing on "all fours" can also induce trembling in proximal arm muscles

- the patient can sit without lower limb trembling

Rubral tremor ("Holmes" tremor)

- the tremor may be present at rest, but is usually most prominent on action or posture, with a prominent intention tremor component

- slower, and more irregular than other tremors, and of greater amplitude (coarse, jerky tremor)

- usually due to midbrain disease (Benedikt's syndrome), thalamic pathology or cerebellar outflow pathway disease

- if due to midbrain disease, the tremor is ipsilateral to the side of the lesion

- accompanied by other abnormal neurological signs, which vary dependent on the site of the pathology

Brief synopsis of Parkinsonism

- some causes of Parkinsonism:-

- clinical features of Parkinson's disease include rest tremor, rigidity, bradykinesia, masklike facies (hypomimia), low volume unmodulated voice (hypophonia), stooped posture on standing, inertia of gait initiation, small shuffling step gait with absence of normal arm swinging, festinant gait (flexed posture walking with rapidly increasing speed to prevent falling), fluttering of the closed eyelids (blepharoclonus), occasional involuntary closure of the eyelids (blepharospasm)

- the three cardinal features of Parkinson's disease include rest tremor, rigidity and bradykinesia (2-out-of-3 needed for the diagnosis)

- the rigidity is lead-pipe or cog-wheeling in type (due to associated tremor)

- the bradykinesia refers to slowness of movement, and paucity of spontaneous movements, and decreased amplitude of movements

- postural instability refers to imbalance and loss of righting reflexes, and is a later develoment

- dementia occurs later in 15 - 30% of patients

- dyskinesia may occur due to levo-dopa therapy; the dyskinesia may be choreoathetotic, ballistic, dystonic or myoclonic, and may vary from mild to severe

- sensory complaints include paresthesia, cold sensations, sensations of shortness of breath without actual respiratory abnormalities, aching and frank pain

- akathisia is common in young patients, and severely affected patients may be compelled to remain in constant motion, unable to remain still for even a minute

- restless leg syndrome is characterised by the presence of nocturnal leg dysesthesias and restless irrestible sterotyped leg movements which lead to sleep deprivation

- differential diagnosis of Parkinson's disease includes:-

Disclaimer: My EM guidemaps reflect my personal approach to problem-solving/managing clinical cases in an ED setting and they should not be regarded as the standard of care. They merely represent the personal opinions of the author and they should only be used in clinical practice if the reader-user has substantial reason to believe that the clinical advice contained in the guidemaps is valid and accurate. The guidemaps are not meant to be "authoritative" and the reader-user should consult standard medical textbooks and expert opinion articles/guidelines for more authoritative advice. The reader-user should particularly confirm all drug doses, their indications and contra-indications, prior to their use.