Signs and Symptoms of Central Pontine Myelinolysis
Central pontine myelinolysis presents with a spectrum of neurological manifestations ranging from sudden weakness, dysphagia, and impaired consciousness to the classic locked-in syndrome, with cerebellar signs like ataxia and dysarthria also occurring in some cases.
Core Clinical Presentations
The clinical picture of CPM varies widely based on the extent and location of demyelination:
Motor and Bulbar Symptoms
- Spastic tetraparesis or quadriparesis - weakness affecting all four limbs 1, 2, 3
- Pseudobulbar palsy - difficulty with speech and swallowing 4, 2, 3
- Dysphagia - swallowing difficulties 1
- Mild tetraparesis in less severe cases 2
Consciousness and Cognitive Changes
- Impaired consciousness or loss of consciousness 1, 4
- Confusion and disorientation 5
- Coma in severe cases 2
- Locked-in syndrome - the most severe presentation where patients are conscious but completely paralyzed except for vertical eye movements 1, 4, 3
Movement Disorders
- Massive myoclonus - involuntary jerky movements, particularly notable as it can be the presenting feature 4
- Jerky movements 5
- Ataxia - incoordination of movement 1, 4
- Intention tremor 1
Cerebellar Signs
When pontocerebellar fibers are affected, patients may present with a benign cerebellar-type syndrome including 1:
- Ataxia
- Intention tremor
- Dysarthria - difficulty articulating speech
Important Clinical Context
The onset of symptoms typically occurs days after the precipitating event (usually rapid correction of hyponatremia), with one case showing severe neurological deficits appearing 10 days after the hyponatremic episode 6. The patient in 5 presented with symptoms following severe hyponatremia correction.
Associated Laboratory Findings
While not a direct symptom, extremely elevated creatine phosphokinase (CPK) levels have been observed in CPM cases, with one report documenting levels up to 92,763 U/L 5. This association warrants further investigation but may serve as a clinical clue.
Clinical Pitfalls
The presentation can range from completely asymptomatic to fatal 3, 7. Not all patients with radiological evidence of central pontine hyperintensities will be symptomatic 7, making clinical correlation essential. The guideline 8 appropriately emphasizes that severe hyponatremia requiring correction carries risk for CPM, particularly when correction is too rapid.
The spectrum of severity means clinicians must maintain high suspicion in at-risk patients (chronic alcoholism, malnutrition, liver disease, rapid electrolyte correction) even with subtle neurological changes, as progression can be rapid and devastating.