Abnormal Movements

Differential Diagnosis

Common Diagnoses

  • RLS
  • Myokymia (Affecting Orbicularis Oculi Muscles)
  • Drug Induced: Including Choreoathetosis, Dystonias, Tardive Dyskinesias and Akathisia (Drugs Include L-Dopa, Tricyclic Antidepressants, Metoclopramide and Antipsychotics)
  • Tourette’s
  • Simple Partial Seizures

Occasional Diagnoses

  • Anxiety/Nervous TIC (Common, but Rarely Presented to the GP)
  • Muscle Fasciculation (e.g. Benign Fasciculation, Motor Neurone Disease)
  • Simple Childhood Tics (Common, but Infrequently Presented)
  • Dystonias
  • Periodic Leg Movements During Sleep

Rare Diagnoses

  • Hemifacial Spasm
  • Myoclonus
  • Chorea (Sydenham’s, Huntington’s)
  • Wilson’s Disease
  • Hemiballismus (e.g. Post Stroke)
  • Hysterical

Ready Reckoner

Key distinguishing features of the most common diagnoses

RLSMyokymiaDrug InducedTourette’sSimple Partial Seizures
Worse at RestYesPossibleNoNoNo
Patient on MedicationPossiblePossibleYesPossiblePossible
Whole Limb AffectedYesNoPossiblePossiblePossible
Other Neurological SignsNoNoNoNoPossible
Childhood OnsetNoNoPossibleYesPossible

Possible Investigations

Likely:FBC, U&E, ferritin, B12, folate, TFT, fasting glucose or HbA1c, calcium.

Possible:CT/MRI of brain or spinal cord, EEG, EMG, nerve conduction studies.

Small Print:Other specialised tests (e.g. for myoclonus and Huntington’s).

  • FBC, ferritin: To assess for iron deficiency in RLS.
  • U&E: Renal failure is a potential cause of RLS and can be implicated in partial seizures.
  • B12, folate: Deficiencies may cause or mimic RLS.
  • TFT: Hypothyroidism may cause RLS.
  • Fasting glucose or HbA1c: Diabetes may cause RLS or partial seizures.
  • Calcium: Hypocalcaemia may be implicated in seizures.
  • CT/MRI of brain or spinal cord: May be required in investigation of fasciculation and seizures (usually arranged after specialist referral).
  • EEG: For investigation of seizures.
  • Other specialised tests: Usually arranged by neurologist to explore the more obscure diagnoses such as Huntington’s chorea and Wilson’s disease.

Top Tips

  • When faced with odd and otherwise inexplicable movements of recent onset in a patient, remember to take a drug history.
  • Bear in mind that abnormal movements can be caused by a drug that the patient has been taking for some time (e.g. tardive dyskinesias).
  • Patients with myokymia sometimes become disproportionately anxious about the symptom, imagining all sorts of possible neurological catastrophes – they may need a lot of reassurance.

Red Flags

  • Childhood tics tend to be single; the patient with the much more significant Tourette’s will probably have multiple tics.
  • Drug-induced dystonias may cause odd posturing and require prompt treatment. The diagnosis is easily overlooked – antipsychotics are common culprits, so it is easy to erroneously attribute the dystonia to psychiatric pathology.
  • Beware of the combination of personality changes and odd movements such as facial grimaces – this could be Huntington’s chorea. Also, don’t be misled by the lack of a positive family history – this background may have been concealed from the patient.
Report errors, or incorrect content by clicking here.