What is the differential diagnosis for a patient with a 3-day history of progressive generalized body weakness, numbness, nape (neck) pain, mild-moderate headache, and a feeling of losing consciousness?

Differential Diagnosis for Progressive Generalized Weakness with Nape Pain and Near-Syncope

Life-Threatening Emergencies Requiring Immediate Exclusion

This presentation represents critical red flags that mandate immediate evaluation for subarachnoid hemorrhage, meningitis, Guillain-Barré syndrome, and cardiac syncope, as the combination of progressive weakness, neck pain, headache, and near-syncope cannot be dismissed without urgent workup 1.

Subarachnoid Hemorrhage (SAH)

• Sentinel headaches occur in up to 43% of patients 2-8 weeks before major aneurysm rupture, and the combination of posterior headache with neck stiffness mandates immediate consideration even without the classic "thunderclap" presentation 1, 2.
• Progressive headache over 3 days is itself a red flag suggesting potential intracranial pathology 1, 2.
• The feeling of losing consciousness may represent transient cerebral hypoperfusion from elevated intracranial pressure 1.
• Misdiagnosis of SAH occurs in up to 12% of cases, with failure to obtain neuroimaging being the most common error 2, 3.

Bacterial or Viral Meningitis/Encephalitis

• Meningitis remains possible without fever, with neck stiffness (nape pain) being a key red flag that cannot be dismissed 1, 2.
• The absence of fever does not exclude bacterial meningitis, and CSF analysis remains the principal diagnostic contributor 1, 2.
• Progressive weakness and altered consciousness (near-syncope) can indicate evolving meningeal inflammation or encephalitis 1.

Guillain-Barré Syndrome (GBS)

• GBS should be considered in any patient with rapidly progressive bilateral weakness, particularly when accompanied by numbness and dysautonomia (near-syncope) 1.
• Disease onset is typically acute or subacute, with patients reaching maximum disability within 2 weeks 1.
• Dysautonomia is common and includes blood pressure or heart rate instability that can manifest as near-syncope 1.
• Pain is frequently reported and can be muscular, radicular, or neuropathic, potentially explaining the nape pain 1.
• Reflexes are decreased or absent in most patients at presentation 1.

Cardiac Syncope

• The feeling of losing consciousness represents presyncope, defined as symptoms before syncope that could progress to complete loss of consciousness 1.
• Cardiac causes of syncope carry the highest mortality risk and must be excluded 1.
• Progressive generalized weakness may indicate reduced cardiac output from arrhythmia, structural heart disease, or mechanical obstruction 1.

Additional Critical Differential Diagnoses

Spinal Cord Compression

• Progressive weakness with neck pain should raise concern for cervical spinal cord pathology, including epidural abscess, hematoma, or tumor 4.
• Spinal cord compression is a time-sensitive emergency requiring urgent identification 4.

Acute Stroke or Posterior Circulation Ischemia

• Vertebrobasilar insufficiency can present with weakness, numbness, and near-syncope 4.
• Brainstem stroke may cause bilateral weakness and altered consciousness 4.

Metabolic or Toxic Encephalopathy

• Approximately 20% of impaired consciousness cases are of metabolic or infectious origin 5.
• Severe electrolyte disturbances (hypokalemia, hyponatremia, hypercalcemia) can cause progressive weakness 5.

Myasthenia Gravis or Neuromuscular Junction Disorders

• Can present with progressive weakness and may have bulbar symptoms 6.
• Weakness typically fluctuates and worsens with activity 6.

Immediate Diagnostic Algorithm

Step 1: Stabilization and Vital Signs

• Stabilize airway, breathing, circulation per ABCDE protocol, and obtain vital signs including orthostatic measurements (drop in systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg suggests orthostatic hypotension) 1, 4, 5.

Step 2: Focused Neurological Examination

• Perform focused neurological examination looking for:
  • Meningismus/nuchal rigidity (neck stiffness) 1, 2
  • Focal neurological deficits 1, 5
  • Reflex abnormalities (decreased/absent suggests GBS) 1
  • Pupillomotor disturbances (red flag for structural lesion) 5
  • Muscle contractions or fasciculations 5

Step 3: Immediate Diagnostic Testing

• Non-contrast head CT immediately (98-100% sensitivity in first 12 hours for SAH) to exclude SAH, mass lesion, or acute stroke 1, 2, 3.
• Electrocardiogram to exclude cardiac arrhythmia or ischemia 1.
• If CT negative but neck stiffness present: lumbar puncture for cell count, protein, glucose, gram stain, culture, and xanthochromia 1, 2.
• Laboratory workup including complete blood count, comprehensive metabolic panel, creatine kinase, and inflammatory markers 4.

Step 4: Additional Testing Based on Initial Results

• If GBS suspected: nerve conduction studies and CSF analysis showing albuminocytologic dissociation (elevated protein with normal cell count) 1.
• If spinal cord compression suspected: urgent MRI of cervical and thoracic spine 4.
• Consider EEG if subclinical seizures suspected 4.

Disposition and Management

Immediate Neurosurgical Consultation

• If SAH confirmed, immediate neurosurgical consultation is required 1, 3.

Hospital Admission Required For:

• Admit for monitoring and further workup if GBS suspected (intravenous immunoglobulin 0.4 g/kg daily for 5 days or plasma exchange) 1.
• Patients with suspected cardiac syncope, unexplained syncope after initial evaluation, or features suggesting serious conditions require specialist cardiovascular or neurological assessment 1.
• Any patient with progressive weakness of uncertain etiology requires admission for monitoring and serial neurological examinations 4.

Critical Pitfalls to Avoid

• Dismissing neck stiffness without neuroimaging can lead to missed SAH, occurring in up to 12% of misdiagnosed cases 1, 2.
• Assuming absence of fever rules out meningitis is incorrect, as clinical characteristics have limited diagnostic accuracy 1, 2.
• Failing to recognize presyncope as a warning sign of impending complete syncope from cardiac causes 1.
• Attributing progressive weakness to benign causes without excluding GBS can delay life-saving treatment, particularly if respiratory muscle involvement develops 1.
• Overlooking the progressive nature of symptoms over 3 days as a red flag for secondary pathology 1, 2.
• Failure to perform lumbar puncture when CT is negative but clinical suspicion for SAH or meningitis remains high 1, 2.