Physical Examination Findings for Central Pontine Myelinolysis
The key physical examination findings for CPM include assessment of motor function (spastic quadriparesis), bulbar function (dysarthria, dysphagia, pseudobulbar palsy), level of consciousness (ranging from encephalopathy to "locked-in" syndrome), and cranial nerve function, particularly nerves V-VIII which traverse the pons. 1, 2, 3
Core Neurological Examination Components
Motor System Assessment
- Spastic quadriparesis with increased muscle tone and hyperreflexia is a hallmark finding 2, 4
- Bilateral upper and lower limb weakness with decreased muscle strength 5
- Progressive neurologic deficits that may evolve to complete quadriplegia 3
Bulbar Function Evaluation
- Dysarthria (difficulty articulating speech) 2
- Dysphagia (difficulty swallowing) 5
- Pseudobulbar palsy with emotional lability, exaggerated jaw jerk, and brisk gag reflex 2, 4
Level of Consciousness
- Encephalopathy of varying degrees 6
- "Locked-in" syndrome in severe cases—patient is awake and aware but cannot move or communicate verbally due to complete paralysis of voluntary muscles except for vertical eye movements 4, 3
- Coma in most severe presentations 2
Cranial Nerve Assessment
- Cranial nerves V-VIII should be specifically examined as they traverse the pons 1
- Look for facial weakness, impaired corneal reflexes, hearing deficits, and vestibular dysfunction
Important Clinical Nuances
Variable Presentation Spectrum
A critical pitfall is assuming CPM always presents with severe neurological deficits. The clinical presentation is highly variable, ranging from severe neurologic disorders to mild neurologic disturbances only 2. Two key points:
- Mild forms of CPM may be difficult to diagnose clinically and can present with subtle findings 2
- The size of the pontine lesion on imaging does not correlate with the severity of neurologic illness or final outcome 2
Neuropsychiatric Manifestations
- Acute psychosis, paranoia, hallucinations, or catatonia may be the primary or sole manifestation, even without focal neurological deficits 6
- Personality changes can occur 6
- These psychiatric symptoms may appear in early stages before classic motor findings develop 6
Associated Physical Findings
Gait and Coordination
- Dizziness and frequent falls may precede other neurological signs 6
- Ataxia when cerebellar involvement is present
General Examination
- Look for signs of underlying conditions: alcohol abuse stigmata, malnutrition, chronic liver disease 3
- Assess hydration status and recent fluid management history 3
Examination Timing Considerations
Physical examination findings may evolve over hours to days, with initial examination potentially showing minimal deficits followed by rapid deterioration 3. Serial neurological examinations are essential, particularly in patients with:
- Recent correction of hyponatremia 4, 3
- Severe hyperglycemia with hyperosmolar state 5
- Underlying conditions like Wernicke's encephalopathy that can mimic CPM 2
Key Differential Diagnostic Clues on Examination
When examining for CPM, distinguish from:
- Pontine gliomas: typically slower progression, may have cranial nerve palsies without the characteristic electrolyte disturbance history 1
- Wernicke's encephalopathy: look for the classic triad of confusion, ataxia, and ophthalmoplegia (nystagmus, lateral rectus palsy) 2
The examination should always be interpreted in context of recent electrolyte abnormalities (particularly rapid sodium correction) or severe hyperglycemia, as these historical features combined with pontine signs make CPM the leading diagnosis 3, 5.