Can excessive jaw chewing be considered an extrapyramidal symptom (EPS)?

Excessive Jaw Chewing as an Extrapyramidal Symptom

Yes, excessive jaw chewing can be considered an extrapyramidal symptom, specifically a form of tardive dyskinesia affecting the orofacial region. 1

Understanding Extrapyramidal Symptoms

Extrapyramidal symptoms (EPS) are a group of movement disorders that result from disruption in the extrapyramidal system, particularly involving dopamine pathways in the basal ganglia. These symptoms typically occur as side effects of medications, especially antipsychotics.

Types of Extrapyramidal Symptoms

According to clinical guidelines, EPS can be categorized into several distinct presentations:

1. Acute Extrapyramidal Side Effects:

   • Dystonia: Sudden spastic contractions of muscle groups, often in the neck, eyes, or torso 1
   • Parkinsonism: Symptoms mimicking Parkinson's disease including bradykinesia, tremors, and rigidity 1
   • Akathisia: Severe restlessness manifesting as pacing or physical agitation 1

2. Tardive (Late-Onset) Syndromes:

   • Tardive Dyskinesia: Involuntary movement disorder consisting of athetoid or choreic movements, primarily in the orofacial region 1
   • Tardive Dystonia: Characterized by slow movements along the body axis culminating in spasms, including facial spasms 1

Jaw Chewing as Tardive Dyskinesia

Excessive jaw chewing specifically falls under tardive dyskinesia, which is characterized by:

• Involuntary, repetitive movements affecting the orofacial region
• Athetoid or choreic movements that may affect any part of the body, but most commonly the mouth, tongue, and jaw 1
• Movements that persist even when the patient is not actively trying to move

The American Academy of Child and Adolescent Psychiatry practice parameters specifically note that tardive dyskinesia commonly presents with movements in the orofacial region 1, which would include excessive jaw chewing.

Clinical Significance

The recognition of excessive jaw chewing as an extrapyramidal symptom is important because:

1. It signals potential medication toxicity: Particularly from antipsychotics, but also potentially from other medications like antidepressants, lithium, anticonvulsants, and antiemetics 2

2. It may be persistent: Unlike acute EPS which typically resolves with medication adjustment, tardive dyskinesia may persist even after discontinuation of the offending agent 1

3. It affects treatment compliance: EPS symptoms are a common reason for medication noncompliance, increasing risk for relapse and greater morbidity 1

Assessment and Monitoring

When excessive jaw chewing is observed:

• Use standardized rating scales like the Abnormal Involuntary Movement Scale (AIMS) or the Extrapyramidal Symptom Rating Scale (ESRS) to document and monitor the symptom 1, 3
• Conduct assessments for dyskinesias at least every 3-6 months in patients on neuroleptic therapy 1
• Document baseline abnormal movements before initiating antipsychotic therapy 1

Management Considerations

If excessive jaw chewing is identified as an extrapyramidal symptom:

1. For tardive dyskinesia:

   • Consider lowering the dose of the antipsychotic medication
   • Consider switching to an atypical antipsychotic with lower EPS risk 1
   • Only continue the current medication and dose if the patient is in full remission and changing medication might precipitate relapse 1

2. For prevention:

   • Use atypical antipsychotics when possible, as they have lower risk of EPS 1
   • Use the lowest effective dose of antipsychotic medication
   • Regularly monitor for early signs of movement disorders 1

Pitfalls and Caveats

• Excessive jaw chewing may be misdiagnosed as a behavioral symptom rather than recognized as medication-induced
• Not all repetitive jaw movements are extrapyramidal in origin; they may be related to anxiety, stereotypic behavior in developmental disorders, or other neurological conditions
• The presence of excessive jaw chewing as an EPS should prompt comprehensive evaluation of all medication regimens, not just antipsychotics 2

Recognizing excessive jaw chewing as an extrapyramidal symptom is crucial for appropriate management and prevention of potentially irreversible movement disorders in patients receiving medications that affect dopaminergic pathways.