Rosen & Barkin's 5-Minute Emergency Medicine Consult (358 page)

• Increased volume of CSF in cranial cavity
  
• Cerebral atrophy also leads to increased CSF in the cranial vault but CSF pressure is not increased
  
• Obstructive hydrocephalus
  is the most common form:
  
  • Obstruction is within ventricular system or in subarachnoid space
    
• Acute
  obstructive
  hydrocephalus may cause rapid rise in intracranial pressure (ICP), rapidly leading to death or permanent cerebral damage
  
• Nonobstructive hydrocephalus
  causes subacute symptoms and is a potentially treatable form of dementia
  
• Also described as “communicating” and “noncommunicating”:
  
  • Communicating hydrocephalus: Flow of CSF is blocked after it exits the ventricles (ventricles still “communicate”)
    
  • Noncommunicating hydrocephalus: Flow of CSF blocked along 1 or more of the passages connecting the ventricles (ventricles do not “communicate”)
    

• Obstructive hydrocephalus:
  
  • Obstruction of:
    
    • Aqueduct of Sylvius (most common, both lateral ventricles and 3rd ventricle dilated, 4th ventricle is spared)
      
  • Aqueductal stenosis can be congenital or acquired (tumor, subarachnoid hemorrhage, post meningitis, idiopathic)
    
    • Foramen of Monro (lateral ventricles dilated, usually both but may be unilateral)
      
    • Foramina of Luschka and Magendie (4th ventricle blocked followed by 3rd and lateral ventricles)
      
    • Subarachnoid space around brainstem (postinfectious or postsubarachnoid hemorrhage [post-SAH] entire system dilated)
      
  • Acute presentations usually secondary to CSF shunt blockage, SAH, or severe head trauma
    
• Nonobstructive hydrocephalus:
  
  • Normal pressure hydrocephalus:
    
    • Increased intracranial volume of CSF without intracranial hypertension
      
    • Increased ventricular size on CT (without volume loss as in atrophy)
      
    • Sometimes called “chronic hydrocephalus”
      
    • Usually occurs due to inadequate CNS absorption
      
• Pediatric hydrocephalus:
  
  • Congenital hydrocephalus owing to neonatal hemorrhage, congenital malformations, or acquired post meningitis secondary to subarachnoid scarring around brainstem
    

DIAGNOSIS

• Obstructive hydrocephalus:
  
  • Headache
    
  • Nausea and vomiting
    
  • Decreased level of consciousness
    
  • Urinary incontinence
    
  • Ocular palsies
    
  • Papilledema, decreased vision
    
  • Pupillary dilation
    
  • Cushing response:
    
    • Raised systolic pressure and bradycardia secondary to increased ICP
      
  • Pediatric patients:
    
    • Full fontanelle, irritability, and lethargy
      
  • BP often elevated
    
  • May present like nonobstructive hydrocephalus if obstruction develops slowly
    
• Nonobstructive hydrocephalus:
  
  • Progressive dementia, somnolence
    
  • Gait disturbance
    
  • Urinary incontinence
    
  • Impaired upward gaze
    
  • Generalized weakness and lethargy
    
  • Dementia is often insidious with subacute onset of progressive intellectual deterioration
    
  • No headache or papilledema
    

• Pediatric patients increase CSF volume slowly:
  
  • Craniomegaly
    
  • Retardation
    
  • Prominent scalp veins
    
  • Impaired upward gaze (setting sun sign)
    

• Onset of symptoms
  
• History of CSF shunt
  
• Nausea/vomiting
  
• Headache
  
• Weakness
  
• Confusion
  
• Visual changes
  
• Incontinence of urine
  

• Thorough neurologic exam:
  
  • Motor
    
  • Sensation
    
  • Deep tendon reflexes
    
  • Gait
    
  • Cranial nerve exam
    
  • Papilledema may be seen
    
• Confusion
  
• Decreased level of consciousness
  
• Palpate CSF shunt if present
  
  • Malfunction indicated by failure to compress (distal shunt malfunction) or failure to refill (proximal shunt obstruction)
    
• Full anterior fontanelle in children:
  
  • Other findings as noted in Signs and Symptoms
    

CT scan of the head w/o contrast will allow assessment of ventricular size and symmetry:

• Aid in diagnosis of cerebral edema, mass lesions, and hemorrhage
  

Lumbar puncture (LP) is typically performed after head CT (for nonobstructive causes):

• Opening pressure on LP will reflect increased ICP in nonobstructive hydrocephalus.
  
• CSF should be sent for routine tests if infection is suspected.
  
  • Gram stain, culture, protein, glucose, and cell count
    

MRI of brain reveals ventricular size and symmetry and may allow for better visualization of masses than CT

LP may be indicated

• Acute cerebral infarction or hemorrhage
  
• Intracranial infection
  
• Mass effect from fast-growing tumor or hematoma
  
• Dementia or delirium of other cause
  
• Toxic or metabolic encephalopathies
  

• Suspect hydrocephalus in an infant whose head circumference is increasing excessively, has progressive lethargy, persistent vomiting, impaired upward gaze, etc.
  
• Congenital anomalies:
  
  • Dandy–Walker malformation
    
  • Arnold–Chiari malformation
    
  • Meningomyelocele
    
  • Choroid plexus papilloma
    
  • Hypoplasia/dysfunction of arachnoid villi
    
• Infections:
  
  • Rubella
    
  • Cytomegalovirus (CMV)
    
  • Toxoplasmosis
    
  • Syphilis
    
  • Bacterial meningitis
    
  • Reye syndrome
    
• Tumors, especially posterior fossa tumors:
  
  • Medulloblastoma
    
  • Astrocytoma
    
  • Ependymoma
    
• Hemorrhage:
  
  • Intraventricular
    
  • Subarachnoid
    

TREATMENT

Cautions:

• Elevated ICP/hydrocephalus cannot be definitively diagnosed in the field
  
• When it is suspected, supplemental O
  ₂
  and airway management (if needed) are indicated
  
• Patients should be transported with head elevated at ∼30°
  
  • HOB should not be elevated if patient is hypotensive for concern about decreased cerebral perfusion
    
  • Initial treatment for hypotension is usually volume expansion with normal saline
    

• Signs of impending herniation:
  
  • Rapid-sequence intubation (RSI)
    
    • Thiopental or etomidate for induction
      
    • Paralytic choice is controversial
      
    • Depolarizing agents (succinylcholine) may transiently increase ICP, this effect may not be clinically significant
      
    • Nondepolarizing agents (rocuronium, vecuronium) may be preferable
      
  • Controlled ventilation to maintain PaCO
    ₂
    at ∼35 mm Hg
    
  • Maintain systolic BP >100 mm Hg (adult) with fluids or pressors.
    
  • Mannitol
    
• If a CSF shunt is present and there are signs of impending herniation:
  
  • Forced pumping of shunt chamber:
    
    • Flush device with 1 mL saline to remove distal obstruction
      
    • Slow drainage of CSF from reservoir to achieve pressure <20 cm H
      ₂
      O
      

• Hydrocephalus does not generally require ED treatment unless:
  
  • Signs of impending herniation
    
  • Acute shunt malfunction
    
• Definitive treatment involves either placement (or revision) of shunting device or treatment of underlying cause (e.g., tumor)
  
• Neurologic symptoms (gait disturbance) or severe headache associated with normal pressure hydrocephalus may respond to removal of CSF by LP (20–30 mL)
  
• If intraventricular hemorrhage (usually from trauma or SAH) causes acute obstructing hydrocephalus a ventriculostomy may be placed in the lateral ventricle
  
• Patients who are agitated or intubated should be sedated
  
• Maintain elevation of the head unless hypotensive
  
• Mannitol may be used
  
• Consider seizure prophylaxis with fosphenytoin
  

• Atropine: 0.02 mg/kg IV (max. 0.1 mg)
  
• Etomidate: 0.2–0.3 mg/kg
  
• Lidocaine: 1 mg/kg IV
  
• Mannitol: 0.5–1.5 g/kg
  
• Rocuronium: 0.6 mg/kg IV
  
• Succinylcholine: 1–1.5 mg/kg IV
  
• Vecuronium: 0.1 mg/kg
  
• Fosphenytoin: 15–20 mg/kg loading dose
  

FOLLOW-UP

Evidence of increased ICP or shunt malfunction requires admission

Patients with presumed normal pressure hydrocephalus may be discharged for follow-up

Involvement of a neurosurgeon may be needed in acute obstructive hydrocephalus or for acute shunt malfunction

• Consider transfer if a neurosurgeon is not available at presenting hospital
  
• Airway management prior to transfer should be considered in acute cases