Differentials

Common

Parkinson disease (PD)

History

unilateral or asymmetric rest tremor, slowed movements, stiffness, micrographia, drooling, difficulty turning over in bed, difficulty with buttons and utensil use, shuffling gait, and decreased arm swing; history of hyposmia, history of rapid eye movement sleep behavior disorder

Exam

masked facies (reduced facial animation), hypophonia, unilateral or asymmetric rest tremor (may be pill rolling), slow or low-amplitude finger taps and hand grips, rigidity, difficulty standing from chair, shuffling gait, stooped posture, decreased arm swing, retropulsion on pull-back testing, stooped posture

1st investigation
  • dopaminergic agent trial:

    positive response to L-dopa or other dopaminergic agent (dopamine agonist). The diagnosis of PD is made clinically, and in cases without atypical features, no additional diagnostic testing is indicated. Warranted if atypical features or unclear clinical diagnosis. In tremor-predominant disease, doses as high as 1200 mg of levodopa may need to be reached before concluding lack of efficacy.

Other investigations
  • head MRI scan:

    normal image in most patients

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  • functional neuroimaging (e.g., PET or single-photon emission CT):

    decreased basal ganglia presynaptic dopamine uptake

Dementia with Lewy bodies

History

fluctuating cognition, cognitive impairment, and parkinsonism occurring within 1 year of each other, visual hallucinations (not related to dopaminergic therapy) and delusions, sensitivity reactions to neuroleptics

Exam

muscle rigidity, stooped posture, cogwheel rigidity, shuffling gait, impairment on cognitive testing

1st investigation
  • none:

    clinical diagnosis

Other investigations
  • head CT or MRI scan:

    normal

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  • serum vitamin B12:

    normal

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  • serum TSH:

    normal

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  • metabolic panel:

    normal

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  • formal neuropsychometric testing:

    visuospatial and visuoconstructive impairment prominent

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  • thyroid function test:

    normal

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Enhanced physiologic tremor

History

tremor noticed in situations of stress, anxiety, or excessive caffeine use; absence of neurologic disease

Exam

anxious appearance; fine high-frequency postural and kinetic tremor that occurs in arms, legs, and voice but not the head

1st investigation
  • none:

    clinical diagnosis

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Other investigations
  • thyroid function test:

    normal

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  • metabolic panel:

    normal

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Hypoglycemia (enhanced physiologic tremor)

History

history of diabetes or glucose intolerance, history of insulin use

Exam

sympathoadrenal or neuroglycopenic symptoms; action tremor

1st investigation
  • serum glucose:

    low

Other investigations
  • thyroid function test:

    normal

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Thyrotoxicosis (enhanced physiologic tremor)

History

weight loss, diaphoresis (excessive sweating), heat intolerance, palpitations, anxiety

Exam

diaphoresis, tachycardia, enlarged thyroid gland; action tremor

1st investigation
  • serum TSH, free T3, free T4:

    TSH: low; free T3: high; free T4: high

Other investigations

    Alcohol withdrawal (enhanced physiologic tremor)

    History

    history of alcohol misuse

    Exam

    tremulousness, seizures, delirium, hallucinations, spider angiomata, gynecomastia, enlarged liver, signs of autonomic hyperactivity, no alcohol for 6 hours produces intention tremor; hypertension; tachycardia

    1st investigation
    • CBC:

      elevated MCV

    • liver function tests:

      elevated gamma-GT

    Other investigations
    • thyroid function test:

      normal

      More

    Essential tremor or essential tremor plus

    History

    tremor mainly affects hands, shaky handwriting or utensil use; positive family history; tremors may improve with alcohol use

    Exam

    postural and/or kinetic tremors of hands, tremors may also involve head and voice; essential tremor occurs in the absence of other neurologic signs; if subtle neurologic signs such as impaired tandem gait, subtle body posturing suggestive of dystonia, or mild memory impairment are present, then essential tremor plus is the more appropriate classification

    1st investigation
    • thyroid function test:

      normal

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    • metabolic panel:

      normal

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    • serum ceruloplasmin:

      normal

      More
    Other investigations

      Drug-induced tremor

      History

      occurs following ingestion of certain drugs; rest tremors can be caused by dopamine receptor blockers such as neuroleptics, atypical antipsychotics, antinausea agents (metoclopramide, prochlorperazine, promethazine), and calcium-channel blockers (flunarizine, cinnarizine) or dopamine depletors (tetrabenazine); action tremors are common following treatment with antidepressants (serotonin-reuptake inhibitors, tricyclics, monoamine oxidase inhibitors), mood stabilizers (lithium), antiepileptic drugs (valproic acid), cardiac drugs (amiodarone), immunosuppressants (cyclosporine, tacrolimus, corticosteroids), asthma drugs (albuterol, theophylline), and stimulants (amphetamines); tremor occurs in a reasonable time frame following drug ingestion

      Exam

      rest or action tremor

      1st investigation
      • none:

        clinical diagnosis

      Other investigations
      • thyroid function test:

        normal

        More

      Uncommon

      Multiple system atrophy

      History

      lightheadedness and syncope, erectile dysfunction, urinary dysfunction, dysarthria, gait difficulty, slow movements, rest tremor, lack of coordination, early postural instability

      Exam

      orthostatic hypotension, parkinsonism, ataxia, hyperreflexia, shuffling or ataxic gait

      1st investigation
      • none:

        clinical diagnosis

        More
      Other investigations
      • head MRI scan:

        cerebellar and/or brainstem atrophy, putaminal hypointensity with slit-like hyperintensity of outer margin of putamen on T2-weighted imaging[17]

      • dopaminergic agent trial:

        minimal or no response to L-dopa

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      Progressive supranuclear palsy

      History

      frequent falls, visual problems, axial rigidity, dysarthria, dysphagia, personality and cognitive change, rest tremor

      Exam

      supranuclear gaze palsy, dysarthria, "surprised" facial expression, axial rigidity, bradykinesia, frontal release signs, cognitive impairment, marked gait instability

      1st investigation
      • none:

        clinical diagnosis

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      Other investigations
      • head MRI scan:

        thinning of the anteroposterior diameter of the midbrain with enlargement of the posterior third ventricle[18]

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      • dopaminergic agent trial:

        negative response to L-dopa

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      Cortical basal degeneration

      History

      asymmetric rest tremor; disorder of skilled, learned, purposeful movement; dystonic limb posturing; alien limb phenomenon

      Exam

      parkinsonism (rest tremor, rigidity, bradykinesia, postural instability), limb apraxia, dystonia, spontaneous and reflex focal myoclonus, rigidity

      1st investigation
      • none:

        clinical diagnosis

      Other investigations
      • head MRI scan:

        usually normal

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      • serum vitamin B12:

        normal

        More
      • serum TSH:

        normal

        More
      • metabolic panel:

        normal

        More
      • formal neuropsychometric testing:

        visuospatial and visuoconstructive impairment prominent

        More
      • dopaminergic agent trial:

        negative response to L-dopa

        More

      Toxin-induced tremor

      History

      history of toxic exposure to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (heroin addicts), carbon monoxide, manganese (may be seen in welders or in patients receiving parenteral nutrition), methanol, or cyanide

      Exam

      parkinsonism (rest tremor, rigidity, bradykinesia, and postural instability)

      1st investigation
      • none:

        clinical diagnosis

      Other investigations
      • head MRI scan:

        shows high signal intensity on T1-weighted images in the globus pallidus in patients actively exposed to high levels of endogenous or iatrogenic manganese, as with intravenous hyperalimentation and cirrhosis, or with environmental-industrial exposure such as with welding, smelting, or manganese mining; may show bilateral globus pallidus lesions in carbon monoxide poisoning

      Postencephalitic parkinsonism

      History

      was common in 1920s but has now virtually disappeared; occurred as a sequel to lethargic encephalitis within a variable period, from days to many years, after the acute process

      Exam

      parkinsonism (rest tremor, rigidity, bradykinesia, postural instability)

      1st investigation
      • none:

        clinical diagnosis

      Other investigations

        Pheochromocytoma (enhanced physiologic tremor)

        History

        headache, sweating, palpitations

        Exam

        hypertension, tachycardia, action tremor

        1st investigation
        • 24-hour urine collection for catecholamines, metanephrines, normetanephrines:

          high

        • serum free metanephrines, normetanephrines:

          high

        Other investigations
        • thyroid function test:

          normal

          More

        Cerebellar tremor (multiple sclerosis, trauma, or stroke)

        History

        complaints of incoordination, imbalance, family history of cerebellar ataxia, history of multiple sclerosis, head trauma, stroke, or cerebellar hemorrhage

        Exam

        coarse irregular kinetic tremor generated proximally, abnormal finger-to-nose testing and heel-to-shin testing, dysdiadochokinesis, wide-based ataxic gait, dysarthria (speech problems)

        1st investigation
        • head MRI scan:

          may see signs of cerebellar atrophy, or may suggest demyelinating disease in multiple sclerosis, or show changes consistent with stroke, trauma, or hemorrhage

        Other investigations
        • thyroid function test:

          normal

          More

        Fragile X tremor ataxia syndrome

        History

        occurs in upper limbs, age >60 years, more common in men, gait ataxia, may be a family history of premature ovarian failure in females and/or intellectual disability (fragile X syndrome) in males

        Exam

        intention tremor, ataxic gait, often have acquired cognitive impairment especially executive dysfunction

        1st investigation
        • head MRI scan:

          middle cerebellar peduncle hyperintensities

        Other investigations
        • genetic testing:

          positive fragile X premutation in FMR1 gene

        • thyroid function test:

          normal

          More

        Orthostatic tremor

        History

        tremor in legs that occurs on standing, accompanied unsteadiness, tremor disappears on sitting or walking

        Exam

        high-frequency tremor of legs when standing

        1st investigation
        • none:

          clinical diagnosis

        Other investigations
        • surface EMG:

          13-18 Hz pattern of alternating contractions of leg muscles

          More
        • thyroid function test:

          normal

          More

        Primary writing tremor

        History

        tremor of hand only when writing

        Exam

        hand tremor when writing only

        1st investigation
        • none:

          clinical diagnosis

        Other investigations
        • thyroid function test:

          normal

          More

        Dystonic tremor

        History

        tremor in a body region (usually head or neck, but may be limb) often with a directional pulling or jerking quality

        Exam

        often irregular head and neck tremor with a jerky, directional quality; patient may use a sensory trick (geste antagoniste) to relieve or diminish tremor; tremor may be very sensitive to task-specific or positional factors e.g., may disappear at a specific position (‘null point’)

        1st investigation
        • none:

          clinical diagnosis

        Other investigations
        • brain MRI:

          normal in most cases

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        Wilson disease

        History

        tremor, dysarthria, incoordination, dystonia, gait abnormalities, psychiatric changes, <40 years of age, hepatitis or cirrhosis

        Exam

        Kayser-Fleischer rings, tremor, dysarthria, dystonia, ataxia

        1st investigation
        • serum ceruloplasmin:

          <18 mg/dL suggests Wilson disease

        • 24-hour urine copper:

          >100 micrograms indicates disease

        • liver function tests:

          abnormal

        • slit-lamp exam:

          Kayser-Fleischer rings, greenish deposits as an arc across the outer rim of the top of the cornea

        • head MRI scan:

          bilateral T2 hyperintensities in any or all of basal ganglia, thalamus, or midbrain; hypointensities can also be seen

        Other investigations
        • liver biopsy:

          liver copper >250 micrograms/g

        • thyroid function test:

          normal

          More

        Rubral tremor

        History

        history of stroke or central nervous system insult such as multiple sclerosis; uncontrollable coarse tremor

        Exam

        tremor of arm with equal rest, action, and intention components

        1st investigation
        • head MRI scan:

          may show damage to the red nucleus or cerebellothalamic pathways

        Other investigations
        • thyroid function test:

          normal

          More

        Functional (psychogenic) tremor

        History

        sudden onset of tremor, history of anxiety or depression, history of sexual or child abuse

        Exam

        tremor that is distractible or can be entrained to a new frequency; may be associated with other nonorganic signs such as give-way weakness; nonanatomic sensory exam; astasia-abasia (inability to either stand or walk in a normal manner)

        1st investigation
        • none:

          clinical diagnosis

        Other investigations
        • thyroid function test:

          normal

          More

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