AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Facial musculature is subject to the same movement disorders as muscles of the limbs or trunk. Myoclonus, dystonia, and other movement disorders present with specific syndromes in the facial musculature. An understanding of the underlying mechanism leads to appropriate diagnostic evaluation and potential treatment.

Although specific treatments are available for many craniofacial movement disorders, botulinum toxin (BTX) chemodenervation has proven useful in many of these disorders, supplanting surgery and medical therapy.

Pathophysiology

First described by Gowers in 1884, hemifacial spasm (HFS) represents a segmental myoclonus of muscles innervated by the facial nerve. The disorder presents in the fifth or sixth decade of life, almost always unilaterally, although bilateral involvement may occur rarely in severe cases. HFS generally begins with brief clonic movements of the orbicularis oculi and spreads over years to other facial muscles (corrugator, frontalis, orbicularis oris, platysma, zygomaticus).

Clonic movements progress to sustained tonic contractions of involved musculature. Chronic irritation of the facial nerve or nucleus, the near-universal cause of HFS, may arise from numerous underlying conditions.

Irritation of the facial nerve nucleus is believed to lead to hyperexcitability of the facial nerve nucleus, while irritation of the proximal nerve segment may cause ephaptic transmission within the facial nerve. Either mechanism explains the rhythmic involuntary myoclonic contractions observed in HFS.

Compressive lesions (eg, tumor, arteriovenous malformation, Paget disease) and noncompressive lesions (eg, stroke, multiple sclerosis plaque, basilar meningitis) may present as HFS. Most instances of hemifacial spasm previously thought to be idiopathic were probably caused by aberrant blood vessels (eg, distal branches of the anterior inferior cerebellar artery or vertebral artery) compressing the facial nerve within the cerebellopontine angle.

Race

All races are affected equally.

Sex

A slight female preponderance exists in HFS.

Age

• Idiopathic hemifacial spasm typically begins in the fifth or sixth decade of life.
• Onset of hemifacial spasm in patients younger than 40 years is unusual and often heralds an underlying neurologic illness (eg, multiple sclerosis).

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

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

• Hemimasticatory spasm
• • Hemimasticatory spasm is analogous to HFS 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 HFS, hemimasticatory spasm responds to treatment with medications and BTX.
  • 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 HFS 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 OMD occurs in conjunction with blepharospasm, the disorder is termed Meige syndrome.
  • Jaw-opening forms of OMD indicate primary involvement of the digastric and lateral pterygoid. Jaw-closing OMD involves the masseter, temporalis, and medial pterygoid.
  • Jaw deviation, indicating predominant involvement of the lateral pterygoid, is rare.
  • BTX is the preferred treatment for OMD 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 BTX 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 HFS.
  • 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 BTX.
  • Most cases are idiopathic and resolve without treatment over several weeks.

Physical

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

Causes

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

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Benign essential
Blepharospasm
OMD
Craniofacial tremor
Facial chorea
Tics
Facial myokymia

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Early cases of HFS may be difficult to distinguish from facial myokymia, tics, or myoclonus originating in the cortex or brainstem.
• • Neurophysiologic testing can be invaluable.
  • Spread and variable synkinesis on blink reflex testing and high-frequency discharges on EMG (with appropriate clinical findings) are diagnostic.
  • Stimulation of one branch of the facial nerve may spread and elicit a response in a muscle supplied by a different branch.
  • Blink reflex studies may reveal synkinesis, which is not present in essential blepharospasm, dystonia, or seizures.
  • Needle EMG shows irregular, brief, high-frequency bursts (150-400 Hz) of motor unit potentials, which correlate with clinically observed facial movements.

Imaging Studies

• Magnetic resonance imaging is the imaging study of choice, especially if an underlying compressive lesion is suspected.
• Perform angiography and/or magnetic resonance angiography prior to a vascular decompression surgical procedure.

Other Tests

• Cerebral angiography offers little diagnostic value in HFS. Ectatic blood vessels rarely are identified, and it is difficult to correlate vessels with the facial nerve. As angiography may identify an aneurysm or vascular anomaly, it often is performed prior to decompressive surgery to clarify the vascular anatomy.

Procedures

• In most patients, the treatment of choice is injection of BTX under EMG guidance.
• • Chemodenervation safely and effectively treats most patients, especially those with sustained contractions.
  • Relief of spasms occurs 3-5 days after injection and lasts approximately 6 months.
• Side effects of BTX injection (eg, facial asymmetry, ptosis, facial weakness) usually are transient.
• • Most patients report a highly satisfactory response.
  • Caution patients that although BTX ablates the muscular spasm, the sensation of spasm often persists.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

• Use medications in patients with noncompressive lesions and early idiopathic HFS.
• Response to medication varies but can be satisfactory in early or mild cases.
• The most helpful agents are carbamazepine and benzodiazepines (eg, clonazepam).
• Often, medication effects attenuate over time, necessitating more aggressive treatment.
• Medications may be used in early HFS (when spasms are mild and infrequent) or in patients who decline BTX injection.

Surgical Care

• Treat compressive lesions surgically.
• • Ectatic blood vessels cause HFS by compressing the facial nerve as it exits the brainstem.
  • Surgical decompression of these blood vessels can yield excellent results.
• Patients with apparently idiopathic HFS may benefit from posterior fossa exploration and microvascular decompression.
• Myectomy rarely is required.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The goal of pharmacotherapy is reduction of abnormal muscle contractions. Botulinum toxin type A is the treatment of choice. Carbamazepine, benzodiazepines, and baclofen also may be used in patients who refuse BTX injections or who are not surgical candidates.

Drug Category: Toxins

Botulinum toxin type A is the drug of choice. It causes presynaptic paralysis of the myoneural junction and reduces abnormal contractions. Therapeutic effects may last 3-6 months.

Botulinum toxin type B is useful in reducing excessive, abnormal contractions associated with blepharospasm; binds to receptor sites on the motor nerve terminals and after uptake inhibits release of acetylcholine, blocking transmission of impulses in neuromuscular tissue; 7-14 d after administering initial dose, assess patients for a satisfactory response; increase doses 2-fold over previously administered dose for patients who experience incomplete paralysis of the target muscle.

Drug Name	Botulinum toxin type B (Myobloc)
Description	When botulinum toxin injection is indicated and type A toxin is ineffective, injection with type B (Myobloc) should be considered.
Adult Dose	Not established: This author suggests starting dose of 500-1000 U IM, divided among abnormally contracting muscles
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity to drug; patients with hypersensitivity to type A toxin, hypersensitivity to type B is significant concern, and use of type B in these patients is not recommended
Interactions	Caution in patients taking aminoglycoside antibiotics or any other drug that interferes with neuromuscular transmission because they may potentiate effect of botulinum toxin
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Likely to cause pain at injection site for a few seconds immediately following administration

Drug Category: Benzodiazepines

May potentiate effects of GABA and facilitate inhibitory GABA neurotransmission. May act in the spinal cord to induce muscle relaxation. Individualize treatment for each patient.

Drug Category: Muscle relaxants

May inhibit transmission of monosynaptic and polysynaptic reflexes at the spinal cord level.

Drug Category: Anticonvulsants

Used to manage severe muscle spasms and provide analgesia and mild sedation. Anticonvulsants are probably the best medications in terms of efficacy and long-term safety when BTX and/or surgery are not an option.

Drug Name	Trileptal (Oxcarbazepine)
Description	Effective in partial complex epilepsy, Oxcarbazepine shows promise in HFS. Oxcarbazepine may be considered when first-line agents (e.g., botulinum toxin, carbamazepine) have failed or are contraindicated.
Adult Dose	Monotherapy: 150 mg or 300 mg PO bid initially; dose may be increased by 300 mg/d q3d; maximum recommended daily dose of 1200-2400 mg in divided dosing; elderly patients may require slower titrations
Pediatric Dose	<4 years Not established 4-16 years Adjunctive therapy: 8-10 mg/kg/d PO divided bid initially, not to exceed 600 mg/d; gradually increase to target dose over 2 wk; target adjunctive dose is based on body weight; 20-29 kg = 900 mg/d, 29.1-39 kg = 1200 mg/d, >39 kg = 1800 mg/d Conversion to monotherapy: 8-10 mg/kg/d PO divided bid initially; gradually reduce the dose of concomitant anticonvulsants over 3-6 wk; may gradually increase oxcarbazepine dose if clinically indicated by increments not to exceed 10 mg/kg/d at qwk to recommended monotherapy dose; monitor patients closely during this transition phase for anticonvulsant adverse effects Monotherapy: 8-10 mg/kg/d PO divided bid; may increase by 5 mg/kg/d q3d to recommended daily dose; maintenance monotherapy dose is based on body weight; 20-24 kg = 600-900 mg/kg/d, 25-34 kg = 900-1200 mg/kg/d, 35-44 kg = 900-1500 mg/kg/d, 45-49 kg = 1200-1500 mg/kg/d, 50-59 kg = 1200-1800 mg/kd/d, 60-69 kg = 1200-2100 mg/kg/d, >70 kg = 1500-2100 mg/kg/d
Contraindications	Documented hypersensitivity
Interactions	May decrease levels of dihydropyridine calcium antagonists and oral contraceptives; can reduce serum concentrations of carbamazepine, phenobarbital, phenytoin and valproic acid; when oxcarbazepine is given in doses above 1200 mg/d may increase phenytoin and phenobarbital serum concentrations significantly; oxcarbazepine can reduce serum concentrations of oral contraceptives and make oral contraceptives ineffective; can increase clearance of felodipine
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	May decrease levels of dihydropyridine calcium antagonists and oral contraceptives; can reduce serum concentrations of carbamazepine, phenobarbital, phenytoin and valproic acid; when oxcarbazepine is given in doses above 1200 mg/d may increase phenytoin and phenobarbital serum concentrations significantly; oxcarbazepine can reduce serum concentrations of oral contraceptives and make oral contraceptives ineffective; can increase clearance of felodipine

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Prognosis

• HFS is a progressive, nonfatal illness. It almost always responds favorably to treatment.

Patient Education

• For excellent patient education resources, visit eMedicine's Procedures Center. Also, see eMedicine's patient education article BOTOX® Injections.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• At initial evaluation, consider HFS a symptom, not a diagnosis.
• An abnormal neurologic examination (except for the facial movements) should prompt the search for an underlying cause (eg, compressive lesion, tumor, stroke).
• Look for demyelinating disease as a cause when HFS presents before 50 years.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• Adler CH, Zimmerman RA, Savino PJ, et al. Hemifacial spasm: evaluation by magnetic resonance imaging and magnetic resonance tomographic angiography. Ann Neurol. Oct 1992;32(4):502-6. [Medline].
• Colosimo C, Chianese M, Giovannelli M, et al. Botulinum toxin type B in blepharospasm and hemifacial spasm. J Neurol Neurosurg Psychiatry. May 2003;74(5):687. [Medline].
• Cruccu G, Inghilleri M, Berardelli A, et al. Pathophysiology of hemimasticatory spasm. J Neurol Neurosurg Psychiatry. Jan 1994;57(1):43-50. [Medline].
• Elston JS. The management of blepharospasm and hemifacial spasm. J Neurol. Jan 1992;239(1):5-8. [Medline].
• Jankovic J, Schwartz K, Donovan DT. Botulinum toxin treatment of cranial-cervical dystonia, spasmodic dysphonia, other focal dystonias and hemifacial spasm. J Neurol Neurosurg Psychiatry. Aug 1990;53(8):633-9. [Medline].
• Jannetta PJ, Abbasy M, Maroon JC, et al. Etiology and definitive microsurgical treatment of hemifacial spasm. Operative techniques and results in 47 patients. J Neurosurg. Sep 1977;47(3):321-8. [Medline].
• Kraft SP, Lang AE. Cranial dystonia, blepharospasm and hemifacial spasm: clinical features and treatment, including the use of botulinum toxin. CMAJ. Nov 1 1988;139(9):837-44. [Medline].
• Mauriello JA, Leone T, Dhillon S, et al. Treatment choices of 119 patients with hemifacial spasm over 11 years. Clin Neurol Neurosurg. Aug 1996;98(3):213-6. [Medline].
• Moller AR. The cranial nerve vascular compression syndrome: I. A review of treatment. Acta Neurochir (Wien). 1991;113(1-2):18-23. [Medline].
• Moller AR. The cranial nerve vascular compression syndrome: II. A review of pathophysiology. Acta Neurochir (Wien). 1991;113(1-2):24-30. [Medline].
• Reimer J, Gilg K, Karow A, et al. Health-related quality of life in blepharospasm or hemifacial spasm. Acta Neurol Scand. Jan 2005;111(1):64-70. [Medline].

Article Last Updated: Oct 11, 2006