Hemifacial Spasm Clinical Presentation

Involuntary facial movement is the only symptom. Fatigue, anxiety, or reading may precipitate the movements.

• Hemimasticatory spasm

  • Hemimasticatory spasm is analogous to hemifacial spasm and occurs with irritation to the motor trigeminal nerve.
  • This rare condition is a segmental myoclonus and presents with unilateral involuntary contractions of the trigeminally innervated muscles of mastication (usually the masseter).
  • Similar to hemifacial spasm, hemimasticatory spasm responds to treatment with medications and botulinum toxin.
  • However, less evidence exists that exploratory surgery benefits patients with this condition.
• Myoclonic movements

  • Myoclonic movements affecting facial musculature also may arise from lesions at the brain or brainstem level.
  • These are distinguished from hemifacial spasm by the distribution of abnormal movements (more generalized, possibly bilateral) and possibly by electrodiagnostic evaluation.
  • Imaging studies may yield an underlying cause.
  • Central myoclonus responds to anticonvulsant management.
• Oromandibular dystonia

  • Oromandibular dystonia (OMD) refers to dystonia affecting the lower facial musculature, predominantly the jaw, pharynx, and tongue.
  • When oromandibular dystonia occurs in conjunction with blepharospasm, the disorder is termed Meige syndrome.
  • Jaw-opening forms of oromandibular dystonia indicate primary involvement of the digastric and lateral pterygoid. Jaw-closing oromandibular dystonia involves the masseter, temporalis, and medial pterygoid.
  • Jaw deviation, indicating predominant involvement of the lateral pterygoid, is rare.
  • Botulinum toxin is the preferred treatment for oromandibular dystonia and is most effective in the jaw-closure type.
  • Medications seldom yield acceptable results. When medications must be used, employ the same agents as for blepharospasm.
  • Because of the risk of aspiration, never inject botulinum toxin into the tongue.
• Craniofacial tremor

  • Craniofacial tremor may occur in association with essential tremor, Parkinson disease, thyroid dysfunction, or electrolyte disturbance.
  • It occurs rarely in isolation.
  • Focal motor seizures must occasionally be distinguished from other facial movement disorders, particularly hemifacial spasm.
  • Postictal weakness and greater involvement of the lower face are distinguishing features of focal motor seizures.
• Facial chorea

  • Facial chorea occurs in the context of a systemic movement disorder (eg, Huntington disease, Sydenham chorea).
  • Chorea is a random, flowing, nonpatterned set of movements.
  • A related disorder, spontaneous orofacial dyskinesia of the elderly, is observed primarily in the edentulous. It usually responds to proper fitting of dentures.
• Tics

  • Facial tics are brief, repetitive, coordinated, semipurposeful movements of grouped facial and neck muscles.
  • Tics may occur physiologically or in association with diffuse encephalopathy.
  • Some medications (ie, anticonvulsants, caffeine, methylphenidate, antiparkinsonian agents) are associated with producing tics.
  • Single, repetitive, stereotyped movements (eg, repetitive grimacing, throat clearing, vocalizations) define a simple tic disorder.
• Facial myokymia

  • Facial myokymia appears as vermicular twitching under the skin, often with a wavelike spread.
  • This is distinguished from other abnormal facial movements by characteristic electromyogram discharges presenting as brief, repetitive bursts of motor unit potentials firing at 2-60 Hz interrupted by periods of silence of up to a few seconds.
  • Facial myokymia may occur with any brainstem process. Severe cases may benefit from botulinum toxin.
  • Most cases are idiopathic and resolve without treatment over several weeks.

• The only physical finding in hemifacial spasm is involuntary facial movements.
• Spontaneous hemifacial spasm manifests with facial spasms that represent myoclonic jerks and are analogous to segmental myoclonus, which may affect other body regions.
• Postparalytic hemifacial spasm (following facial nerve trauma such as Bell palsy) manifests as facial synkinesis and contracture.

• Idiopathic
• Vascular compression
• Facial nerve compression by mass
• Brainstem lesion such as stroke or multiple sclerosis plaque
• Secondary to trauma or Bell palsy