What is the treatment approach for pathological smile rises sardonicus?

Treatment Approach for Risus Sardonicus (Pathological Smile)

Botulinum toxin injections should be the first-line treatment for pathological risus sardonicus, as they effectively reduce abnormal muscular contractions with minimal side effects. 1

Understanding Risus Sardonicus

Risus sardonicus is a pathological facial expression characterized by:

• Sustained, involuntary contraction of facial muscles producing a grimacing smile appearance 2
• Often associated with dystonic movements of facial muscles 2
• Can occur following neurological events such as thalamic hemorrhage or as part of focal dystonia 2

Treatment Algorithm

First-Line Treatment: Botulinum Toxin

Botulinum toxin is the treatment of choice for risus sardonicus due to its:

• Ability to cause transient, non-destructive flaccid paralysis of affected muscles by inhibiting acetylcholine release from nerve terminals 1
• Effectiveness in treating focal dystonia, including facial dystonia 1
• Excellent symptom control lasting 3-6 months per treatment 1
• Minimal side effects compared to other interventions 1

Administration:

• Intramuscular injection into the affected facial muscles 1
• Can be performed on awake, ambulatory patients with minimal discomfort 1
• May require repeat treatments every 3-6 months 1

Potential side effects:

• Temporary dysphagia
• Breathy voice
• Excessive weakness in adjacent muscles 1

Second-Line Options for Refractory Cases

For cases not responding to botulinum toxin:

1. Surgical interventions may be considered:

   • Anterior belly of digastric muscle transfer has shown superior cosmetic results with less donor-site morbidity 3
   • Free muscle transfers (e.g., extensor digitorum brevis transfer) for complex cases 3

2. Deep Brain Stimulation (DBS) may be considered for severe, treatment-refractory dystonia:

   • Targets may include thalamic nuclei or globus pallidus interna 1
   • Should only be considered after failure of botulinum toxin and other medical therapies 1
   • Requires comprehensive neurological, neuropsychiatric, and neuropsychological assessment 1

Special Considerations

Underlying Causes

• If risus sardonicus is associated with tetanus infection, immediate treatment with tetanus antitoxin and antibiotics is essential 4
• When caused by thalamic hemorrhage or stroke, addressing the underlying neurological condition is critical 2
• In cases of medication-induced dystonia, consider medication adjustment 1

Adjunctive Therapies

• Speech and language therapy may help with functional communication issues resulting from facial muscle dysfunction 1
• Behavioral techniques can help patients develop compensatory strategies 1

Monitoring and Follow-up

• Regular follow-up to assess treatment efficacy and need for repeat botulinum toxin injections 1
• Monitor for side effects, particularly dysphagia or respiratory issues 1
• Assess improvement in quality of life and functional communication 1

Important Caveats

• Botulinum toxin provides symptomatic relief but is not curative for underlying dystonia 1
• Treatment response should be assessed using both objective measures and patient-reported outcomes 1
• Women may show better spontaneity of facial movements after rehabilitation compared to men 5
• Patients should be informed that repeated treatments will likely be necessary 1