Aka
- Opercular Syndrome, OPS
Definition
- A rare cortical type of pseudobulbar palsy characterized by paralysis of facial, lingual, pharyngeal, and masticatory voluntary muscles, while autonomic, involuntary, and reflexive movements remain intact.
Pathophysiology
- Caused by lesions in the operculum or their projections to the brainstem nuclei.
- Bilateral involvement of corticobulbar tracts is required; however, unilateral stroke can trigger symptoms if a contralateral old lesion existed (previously compensated).
- Preserved spontaneous and emotional movements due to intact extrapyramidal and limbic systems (autonomic-voluntary dissociation).
- Anatomical sites often affected: posterior inferior frontal gyrus and inferior precentral gyrus.
Neuroanatomical Basis
- Opercular region connects with cranial nerves V, VII, IX, X, and XII.
- Damage disrupts voluntary motor control from the motor cortex but preserves emotional expression from subcortical circuits (thalamus, hypothalamus, extrapyramidal tracts).
- Autonomic-Voluntary Dissociation:
- Voluntary facial, tongue, and pharyngeal movements lost.
- Involuntary/expression-related movements (smiling, crying, yawning) are retained.
Aetiologies
- Ischemic or embolic stroke (most common).
- Others: trauma, tumors, multiple sclerosis, perisylvian cortical dysplasia, ADEM, moyamoya disease, vasculitis, neurodegeneration.
Radiology
- MRI may show bilateral opercular or corona radiata infarcts
- Example case:
- Preexisting left pontine ischaemic changes.
- New small right corona radiata infarct → bilateral weakness of speech and swallowing muscles.
- A, T2 fluid-attenuated inversion recovery (FLAIR) MRI demonstrates substantial preexisting ischemic burden, notably in the left pons.
- B, Our patient compensated for these previous insults, until a small unilateral stroke of the right corona radiata caused bilateral weakness of the muscles crucial for speaking and swallowing
DDx (vs. Bulbar Paralysis)
Feature | Opercular Syndrome (Foix–Chavany–Marie) | Bulbar Paralysis |
Site of Lesion | Bilateral cortical or subcortical opercular regions (upper motor neuron) | Brainstem cranial nerve nuclei or lower motor neurons |
Eye Movements | Normal | May be affected if brainstem involvement extends |
Facial, Lingual, Pharyngeal Movements | Voluntary movements lost, involuntary movements preserved | Both voluntary and involuntary movements impaired |
Reflexes (Jaw Jerk, Gag) | Preserved or exaggerated (hyperreflexia) | Diminished or absent |
Muscle Tone | Increased (spastic) | Decreased (flaccid) |
Muscle Atrophy | Absent | Present |
Fasciculations | Absent | Present |
Speech | Anarthria or severe dysarthria with preserved emotional expression | Dysarthria with loss of both voluntary and emotional expression |
Emotional/Automatic Movements | Preserved (smiling, crying, yawning) | Lost |
Common Etiology | Bilateral opercular stroke, demyelination, trauma | Motor neuron disease, brainstem infarct, Guillain–Barré syndrome |
Prognosis | Poor, limited recovery of speech/swallowing | Variable, depending on etiology |
Prognosis and Treatment:
- Outcome depends on the underlying cause (usually poor).
- Partial recovery of speech, chewing, swallowing rare.
- Major complication: aspiration pneumonia due to dysphagia.
- Rehabilitation focuses on speech therapy and safe feeding strategies.
- Prevention relies on control of recurrent cerebrovascular events.
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