What are the key points to focus on during a physical examination for the clinical diagnosis of Central Pontine Myelinolysis (CPM)?

Physical Examination for Central Pontine Myelinolysis (CPM)

The physical examination for CPM should focus on identifying progressive neurological deficits including spastic quadriparesis, pseudobulbar palsy, dysarthria, and signs of "locked-in" syndrome, while recognizing that early presentations may show minimal or no focal deficits despite severe underlying pathology. 1, 2

Core Neurological Assessment

Motor Examination

• Assess for spastic quadriparesis by testing muscle strength in all four extremities, noting any progressive weakness pattern that may evolve over hours to days 1, 3
• Evaluate muscle tone for spasticity, which is characteristic of pontine involvement 1
• Test deep tendon reflexes for hyperreflexia and pathological reflexes (Babinski sign), indicating corticospinal tract involvement 3

Bulbar Function

• Examine for pseudobulbar palsy including dysarthria (slurred or difficult speech), dysphagia (difficulty swallowing), and emotional lability 1, 3
• Assess facial movements bilaterally for weakness or asymmetry 3
• Test gag reflex and palatal elevation to identify bulbar dysfunction 1

Level of Consciousness and Cognitive State

• Determine if the patient exhibits "locked-in" syndrome: preserved consciousness with quadriplegia and inability to speak, but retained vertical eye movements and blinking 1, 2
• Assess for encephalopathy of varying degrees, from mild confusion to coma in severe cases 3
• Screen for acute psychosis, personality changes, paranoia, or hallucinations, which may be the primary or sole manifestation in early CPM, even without focal neurological deficits 4

Critical Clinical Context

Associated Findings

• Document any history of dizziness, frequent falls, or generalized weakness that preceded neurological deterioration 4
• Examine for signs of chronic alcoholism (the most common underlying condition, present in 39.4% of cases), including stigmata of liver disease, malnutrition, or alcohol withdrawal 3
• Assess hydration status and recent fluid management, as iatrogenic precipitation through inappropriate rehydration is frequent 1

Extrapontine Involvement

• Perform comprehensive neurological examination to identify potential extrapontine myelinolysis, which may present with additional movement disorders, behavioral changes, or cortical signs 4, 3

Important Clinical Pitfalls

Early CPM may present with normal physical examination or only neuropsychiatric symptoms without focal deficits, making clinical diagnosis challenging in the initial stages 4, 2. In one documented case, a patient developed acute psychosis as the main manifestation with no focal neurological deficits on initial examination, despite subsequent MRI confirmation of CPM 4.

Physical examination findings lag behind the underlying pathological process—initial examination may be unremarkable even when demyelination is already occurring 2. Serial examinations are essential, as neurological deficits typically progress over hours to days 1, 3.

Clinical improvement precedes radiological resolution by several months, so improving examination findings do not necessarily correlate with MRI normalization 2.

Examination Sequence Priority

1. Mental status and psychiatric assessment first (given that acute psychosis may be the sole early manifestation) 4
2. Cranial nerve examination focusing on bulbar function 1, 3
3. Motor examination for quadriparesis and spasticity 1, 2
4. Assessment for locked-in syndrome (preserved vertical eye movements and blinking despite complete motor paralysis) 1, 2
5. Evaluation of consciousness level ranging from alert to comatose 3