What are the symptoms and treatment of uncal herniation?

Symptoms and Treatment of Uncal Herniation

Uncal herniation is a life-threatening neurological emergency requiring immediate aggressive intervention with mannitol or hypertonic saline, hyperventilation, head elevation, and urgent neurosurgical decompression to prevent mortality and improve neurological outcomes. 1

Clinical Presentation

Cardinal Signs and Symptoms

• Altered level of consciousness - progressing from lethargy to coma
• Pupillary changes - ipsilateral pupillary dilation (mydriasis) and sluggish/absent light reflex
• Contralateral hemiparesis - due to compression of the cerebral peduncle
• Cushing's triad - hypertension, bradycardia, and irregular respirations
• Headache - often severe and progressive
• Vomiting - frequently projectile

Progression of Symptoms

1. Early signs:

   • Headache
   • Decreased level of consciousness
   • Ipsilateral pupillary dilation
   • Contralateral weakness

2. Late signs (indicating advanced herniation):

   • Bilateral pupillary dilation
   • Decerebrate or decorticate posturing
   • Respiratory pattern changes (Cheyne-Stokes breathing)
   • Bradycardia
   • Hypertension
   • Loss of consciousness progressing to coma

The progression can be extremely rapid, with neurological deterioration occurring within minutes to hours 1.

Emergency Management

Immediate Interventions

1. Airway management:

   • Immediate endotracheal intubation for patients with Grade III-IV encephalopathy 1
   • Hyperventilation to PaCO₂ of 30-35 mmHg (temporary measure only) 1

2. Hyperosmolar therapy:

   • Mannitol: 0.5-1 g/kg IV over 15-20 minutes 1, 2
     • Maximum dose: 2 g/kg
     • Duration of action: 2-4 hours
     • Requires urinary catheter placement due to diuretic effect
   • Hypertonic saline (3%): 2 ml/kg as alternative, especially in patients with renal insufficiency 1

3. Patient positioning:

   • Elevate head of bed 20-30° to facilitate venous drainage 1
   • Maintain neck in neutral position

4. Blood pressure management:

   • Maintain cerebral perfusion pressure (CPP) between 60-70 mmHg 1
   • Treat hypertension with increased sedation and small boluses of labetalol
   • Treat hypotension with α-agonists after correcting hypovolemia

Surgical Interventions

• Decompressive craniectomy - urgent neurosurgical consultation for potential surgical decompression 1
• Evacuation of mass lesions - removal of hematomas, tumors, or abscesses causing the herniation
• Temporal lobectomy - may be considered in severe cases with traumatic subdural hematoma 3

Monitoring and Follow-up

Critical Parameters to Monitor

• Neurological status (GCS, pupillary response, motor function)
• Intracranial pressure (ICP)
• Cerebral perfusion pressure (CPP)
• Serum osmolality (maintain <320 mOsm/L)
• Electrolytes (every 4-6 hours)
• Renal function
• Fluid balance

Contraindications and Precautions

• Mannitol is contraindicated in:
  • Severe renal disease
  • Congestive heart failure
  • Active intracranial hemorrhage (except during craniotomy) 2
• Prolonged hyperventilation can cause cerebral ischemia; use only for short-term management 1
• Corticosteroids should not be used to control elevated ICP 1

Prognosis

The prognosis for uncal herniation depends on:

1. Speed of intervention - rapid treatment significantly improves outcomes 4
2. Glasgow Coma Scale at presentation - lower GCS correlates with worse outcomes 4
3. Underlying cause - certain causes (e.g., traumatic brain injury) may have better outcomes than others
4. Age - younger patients may have better recovery potential 5

While traditionally considered fatal if untreated, studies have shown that uncal herniation can be reversible with prompt and appropriate interventions 4, 5, 6. The Glasgow Coma Scale at presentation is the most significant predictor of outcome, with higher GCS values correlating with better recovery 4.