Brain Teasers: Decoding Encephalopathy One Case at a Time

Notes

General Workup

  • History
    • Majority of cases can be identified or at least significantly narrowed from history
    • Include medical conditions (liver disease, CKD, etc)
    • Immune status
    • Medications (including meds they have not taken and may be withdrawing from)
    • Elicits or exposures
  • Physical Exam
    • Thorough neuro exam
    • Hold sedation if possible
    • Pupils, gaze deviation, nystagmus
    • Delirium?
  • Lab tests
    • Chemistries
    • LFTs
    • ABG
    • B12, thiamine, TSH
  • Neurodiagnostic testing
    • Noncontrast CTH, CTA head and neck
    • MRI
    • EEG
    • ONS

Toxic-Metabolic Encephelopathies

  • History
    • present from admission or developed during admission
    • risk factors: nutritional deficiencies, pre-existing medical conditions, polypharmacy, recreational drug use
  • Physical
    • Oculomotor dysfunction, ataxia, asterixis, clonus, rigidity, roving eye movement
  • Labs
    • BMP, LFTs, ammonia, urine/serum toxicology
  • Metabolic causes:
    • Renal failure
    • Hypo/hypernatremia
    • Liver failure
  • Toxic Causes
    • Review current meds
    • UDS
    • True positives may be incidental
    • False positives
    • Ex metabolites of bupropion may result in false positive for meth
    • Consider withdrawal
  • Wernicke’s Encephalopathy
    • History of EtOH
    • History of Gastric Bypass (nutritional loss)
    • Prolonged hospitalization
    • Extreme weight loss
    • Dialysis
  • Antidote
    • Many toxins have specific antidotes
  • Evaluate and treat cerebral edema
    • Common with hepatic encephalopathy
  • Treat underlying cause
    • Ultimately the treatment for metabolic encephalopathy
    • Lactulose
    • CRRT/HD
    • Thiamine
    • Electrolyte replacement

Primary CNS Disorders

  • Non-Convulsive Status Epilepticus
  • Stroke
  • Cerebral Vasospasm
    • Usually associated with SAH but also TBI, immunosuppressant meds, toxic exposures, drugs of abuse, RCVS
  • History
    • Isolated AMS without other illness
    • AMS preceded other illness
    • AMS out of proportion to other illness
    • History of seizures, other neurological disease
  • Physical
    • Unilateral weakness/paralysis
    • Pupillary changes/gaze deviation
  • Labs
    • Hypercoagulability/coagulopathy
  • CT
    • Non-con CTH
    • If rapid onset, add CTA H/N
    • If hx of thrombophilia, lack of traditional risk factors, subacute onset, headache, peripartum: add CTV
  • EEG
    • Non-convulsive status can present in a variety of ways
    • Continuous EEG is preferred
  • TCD
    • If CT shows pathology with concern for cerebral perfusion changes
    • RCVS
    • TBI
    • SAH
    • Cerebral vasospasm presents with stroke-like symptoms
  • MRI
    • Provides more detailed images and may ultimately be needed to find definite cause
    • Logistical problems make this less attractive in the urgent setting
  • Ultimately we need to treat the underlying cause
    • If stroke, may need thrombolytics and or thrombectomy
    • If hemorrhage may need reversal of anticoagulation
    • If seizures may need additional AEDs
  • Neurology consult may be helpful
  • ENLS: See link below

CNS Infection

  • History
    • Fever PLUS headache, photophobia, or seizures
    • Exposure or risk of exposure (dorms, military, incarceration)
    • Immunosuppression
    • TBI or neurosurgical procedures
    • Recent systemic infection
  • Physical
    • Rashes
    • Radiculopathy
    • Signs of extra-CNS infection
  • Labs
    • ESR
    • CRP
    • Blood cultures
    • Targeted assays
  • Lumbar Puncture
    • If OP is elevated, consider EVD or LD
    • If OP is normal, non-invasive monitoring (ONS, TCDs, pupil exams)
  • CSF diversion if concern for communicating hydrocephalus
  • ENLS: See link below

Approach to the Undifferentiated Patient

  • Potentially reversible
  • Requires specific therapy to reverse
  • Substantial risk

Additional Resources

Albin CSW, Cunha CB, Glaser TP, Schachter M, Snow JW, Oto B. The Approach to Altered Mental Status in the Intensive Care Unit. Semin Neurol. Published online August 13, 2024. doi:10.1055/s-0044-1788894 [Click here to read] – This paper has a lot of good tables that expound on some of the differentials mentioned in the talk

General Neurocritical Care Resources

Emergency Neurological Life Support Course

Emergency Neurological Life Support Protocols (FREE)

Essentials of Neurocritical Care

Neurocritical Care Society Guideline for Management of Status Epilepticus

Academic Life in Emergency Medicine Guide to Management of Intracranial Hemorrhage

Neurocritical Care Society Guideline for Reversal of Anticoagulation in Intracranial Hemorrhage

Internet Book of Critical Care – Neurology Section

Optic Nerve Sheath Assessment for Raised ICP

Transcranial Doppler Assessment for Vasospasm

CSF Profile Analysis