Synkinesis

Original Editor - Wendy Walker

Lead Editors  

Introduction & Definition[edit | edit source]

Synkinesis (AKA aberrant regeneration) occurs after injury to the facial nerve, as a common sequelae of facial palsy.

The cause of the injury may be simple Bell's Palsy, the less common condition Ramsey Hunt Syndrome, surgical damage (eg. during surgical removal of Acoustic Neuroma) or trauma (skull fractures).

Synkinesis = "syn" meaning "together and "kinesis" meaning movement. Therefore synkinesis means "moving together" or "mass movement".

Synkinesis is an involuntary movement accompanying a voluntary one. These unintentional movements are thought to be caused by an undifferentiated regeneration of the facial nerve that occurs after being compressed or damaged.

Clinically Relevant Anatomy
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The facial nerve is the 7th cranial nerve, and it controls the muscles of facial expression.

Refer to the Facial Nerve page for more details of its anatomy. 

Mechanism of Injury / Pathological Process
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The unintentional or mass movements are thought to be caused by an undifferentiated regeneration of the facial nerve that occurs after being compressed or damaged.

There are 3 possible mechanisms which it is thought could be the cause of synkinesis:

  1. Aberrant regeneration[1][2] "miss-wiring"  (axons project from the facial nucleus to incorrect peripheral muscle groups)
  2. Ephaptic transmission[3] (electrical cross-talk between nerve branches)
  3. Nuclear hyperexcitability[4]

It is possible that a combination of 2 or all 3 of these mechanisms is involved.

Clinical Presentation[edit | edit source]

Following flaccid facial palsy, as the patient experiences recovery and reinnervation of the affected side of the face, they also experience the involuntary linking of movements which are typical of synkinesis.

The effects which are most commonly observed[5] are:

  • when moving the mouth (eg. smile, lip pucker, when eating) the eye on the affected side moves towards partial (or occasionally full) closure, whereas the unaffected eye remains wide open
  • when raising the eyebrows or closing the eyes, the corner of the mouth on the affected side of the face raises

Scoring/measuring synkinesis[edit | edit source]

The most commonly (by surgeons and physicians) used measure of facial range of movement is the House-Brackmann scale[6].

Unfortunately, this does not have a rating for the aberrant linking of movements which occur in synkinesis.

The Sunnybrook Facial Grading System[7] is a more comprehensive scoring system for facial range of movement, has a section dedicated to rating the presence of synkinesis movements[8].

Management / Interventions
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Physiotherapy interventions[edit | edit source]

The following physiotherapy interventions can be effective in reducing or minimising synkinesis:

Non-physiotherapy interventions[edit | edit source]

  • Botulinum Toxin injections

Differential Diagnosis[edit | edit source]

Synkinesis is a clinical diagnosis, and is usually easy to diagnose as the patient will demonstrate clear linking of facial movements on the affected side only and will have a history of facial palsy.

Occasionally it can be confused with the following conditions:

  • Facial dystonia
  • Essential blepharospasm
  • Essential hemifacial spasm

Resources
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The Facial Palsy UK charity has a comprehensive website, and this is the page explaining more about synkinesis.

Recent Related Research (from Pubmed)[edit | edit source]

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References[edit | edit source]

References will automatically be added here, see adding references tutorial.

  1. ↑ Moran CJ, Neely JG. (1996). "Patterns of facial nerve synkinesis.". Laryngoscope 106 (12): 1491–6
  2. ↑ Choi D, Raisman G. (2004). "After facial nerve damage, regenerating axons become aberrant throughout the length of the nerve and not only at the site of the lesion: an experimental study.". Br J Neurosurg. 18 (1): 45–8
  3. ↑ Sadjadpour K. (1975). "After Postfacial palsy phenomena: faulty nerve regeneration or ephaptic transmission?". Brain Res. 95 (2-3): 403–6
  4. ↑ Sibony PA, Lessell S, Gittinger JW Jr. (1984). "Acquired oculomotor synkinesis.". Surv Ophthalmol. 28 (5): 382–90
  5. ↑ Frequency and location of synkineses in patients with peripheral facial nerve paresis.fckLRBeurskens CH1, Oosterhof J, Nijhuis-van der Sanden MW
  6. ↑ House JW, Brackmann DE (1985). "Facial nerve grading system". Otolaryngol Head Neck Surg 93: 146–147
  7. ↑ Otolaryngol Head Neck Surg. 1996 Mar;114(3):380-6.fckLRDevelopment of a sensitive clinical facial grading system.fckLRRoss BG1, Fradet G, Nedzelski JM.
  8. ↑ Laryngoscope. 2010 May;120(5):1038-45. doi: 10.1002/lary.20868.fckLRSunnybrook facial grading system: reliability and criteria for grading.fckLRNeely JG1, Cherian NG, Dickerson CB, Nedzelski JM
  9. ↑ Brach JS, VanSwearingen JM, Lenert J, Johnson PC. (1997). "Facial neuromuscular retraining for oral synkinesis.". Plast Reconstr Surg. 99 (7): 1922–31
  10. ↑ Manikandan N. (2007). "Effect of facial neuromuscular re-education on facial symmetry in patients with Bell's palsy: a randomized controlled trial.". Clin Rehabil.. 21 (4): 338–43
  11. ↑ Ross B, Nedzelski JM, McLean JA. (1991). "Efficacy of feedback training in long-standing facial nerve paresis.". Laryngoscope. 101 (7): 744–50
  12. ↑ Int Rehabil Med. 1982;4(2):67-74.fckLRFacial paralysis rehabilitation: retraining selective muscle control.fckLRBalliet R, Shinn JB, Bach-y-Rita P

 

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