Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 13 Sept 2026Clinical review pending
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Atypical facial spasm with acute neurology
New facial movement with weakness, brainstem signs, severe headache, altered consciousness, fever or a new cranial neuropathy is not routine primary hemifacial spasm.
Action: Stabilise the patient, perform an urgent neurological examination and arrange cause-directed emergency imaging or stroke, infection and neurosurgical assessment rather than delaying for an outpatient movement-disorder label.
Synopsis
Recognise the characteristic unilateral facial contraction pattern, exclude important mimics and secondary causes, interpret neurovascular contact cautiously, and select symptomatic or surgical treatment with informed risk discussion.
Hemifacial spasm causes involuntary contractions in muscles supplied by one facial nerve, commonly beginning in orbicularis oculi and later spreading down the same side of the face.
Primary disease is commonly associated with pulsatile vascular compression near the susceptible proximal facial-nerve segment; secondary disease follows another lesion or injury and needs cause-specific care.
Diagnosis remains clinical. MRI evaluates the nerve and posterior fossa, excludes secondary pathology and maps a possible conflict, but incidental neurovascular contact is not diagnostic by itself.
Key red flags
Sudden facial weakness, dysarthria, diplopia, limb ataxia or sensory loss suggests stroke or another brainstem lesion rather than uncomplicated hemifacial spasm.
Bilateral contractions, sustained dystonia, impaired awareness or spread beyond facial-nerve muscles should prompt reconsideration of blepharospasm, focal seizure or functional movement disorder.
Young onset, rapid progression, hearing change, other cranial neuropathies or a previous facial palsy increases concern for tumour, demyelination, inflammation or structural facial-nerve disease.
Painful vesicles, fever, meningism or an infected wound requires an infection pathway; visible twitching must not distract from systemic or intracranial illness.
Emergency alternative
Acute facial weakness or additional brainstem and limb signs requires urgent stroke or structural-lesion assessment rather than a routine spasm clinic.
Reasoning priorities
01
MRI brain with high-resolution posterior-fossa cranial-nerve sequences
Exclude a mass, demyelination or other secondary cause and demonstrate the facial nerve, neighbouring vessels and operative anatomy.
Proximal arterial contact accompanied by indentation, displacement or atrophy supports a causal conflict, but isolated contact is frequent and must be matched to typical unilateral symptoms.
Worked reasoning
Worked caseProgressive unilateral periocular and lower-face contractions
A middle-aged adult has typical same-side spread, preserved awareness and no additional neurological deficit.
Confirm the facial distribution, time course and disability; examine every cranial nerve and screen for seizure features, dystonia, tic and a previous facial palsy.
Obtain MRI with appropriate posterior-fossa sequences to exclude secondary pathology and assess whether a proximal neurovascular conflict plausibly matches the side and nerve.
Offer botulinum toxin through an experienced service when symptomatic treatment is preferred, documenting target muscles, benefit duration and weakness or ocular adverse effects.
If disability persists and durable treatment is desired, refer for specialist microvascular-decompression assessment rather than equating referral with an automatic operation.
National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 13 Sept 2026; clinical approval remains outstanding.
Hemifacial spasm updateJournal review published 2025; full available body read 13 September 2026. Abstract; clinical presentation and differential diagnosis; imaging; botulinum toxin; microvascular decompression; outcomes and complications. Supports: Clinical spread of hemifacial spasm, distinction from mimics, MRI purpose, symptomatic botulinum toxin and selected microvascular decompression. Limits: Narrative review of predominantly adult primary hemifacial spasm; not a UK commissioning guideline and not a fixed operative threshold. Chapter-specific use: hemifacial-spasm.
Imaging of neurovascular compression syndromesAmerican Journal of Neuroradiology review published 2016; full body read 13 September 2026. Neurovascular compression principles; transition-zone anatomy; trigeminal neuralgia, hemifacial spasm and glossopharyngeal neuralgia imaging sections. Supports: Symptomatic contact is more persuasive near the vulnerable transition zone with nerve displacement or atrophy; ordinary contact is common and may be incidental. Limits: Imaging review, not a treatment guideline; radiology supports but does not replace syndrome diagnosis or multidisciplinary selection. Chapter-specific use: hemifacial-spasm.
MRI neurovascular compression study in hemifacial spasmBrain 2021; article body read 13 September 2026. Methods defining arterial contact location and severity; symptomatic versus asymptomatic side comparisons; discussion of proximal contact and deformity. Supports: Arterial compression at the proximal susceptible facial-nerve segment is associated with the symptomatic side; isolated contact requires clinical correlation. Limits: Observational imaging study in hemifacial spasm; cannot make MRI contact alone diagnostic or prove benefit from surgery. Chapter-specific use: hemifacial-spasm.