Hydrocephalus

Aka: Hydrocephalus, Chronic Hydrocephalus

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II. Definitions

  1. Hydrocephalus
    1. Increase in Cerebrospinal Fluid (CSF) volume in the Central Nervous System (CNS)
  2. Acute Hydrocephalus
    1. Neurologic Emergency
    2. Complete Obstructive Hydrocephalus
  3. Chronic Hydrocephalus
    1. Described below
    2. Results in Dementia
  4. Hydrocephalus ex vacuo
    1. Ventricles appear enlarged due to severe cerebral atrophy
    2. Not a true Hydrocephalus

III. Risk Factors

  1. Meningitis
  2. Intraventricular Hemorrhage
  3. Meningomyelocele (Spina bifida)

IV. Pathophysiology

  1. Children
    1. Ventricular obstruction (noncommunicating)
      1. Aqueductal stenosis
      2. Incomplete Magendie or Luschka foramina development
    2. Associated with other neurologic abnormalities
      1. Microgyria or Macrogyria
      2. Porencephaly
      3. Agenesis of corpus callosum or cerebellar vermis
      4. Fusion of Cerebral Hemispheres
      5. Spina bifida, Meningocele or Encephalocele
      6. Syringomyelia or Hydromyelia
      7. Arnold-Chiari Malformation
  2. Adults
    1. Extraventricular obstruction (communicating)
      1. Occurs from subarachnoid space blockage
    2. Rarely Noncommunicating from aqueductal stenosis

V. Causes

  1. Nonobstructive (ex vacuo)
    1. Alzheimer's Disease
    2. Pick's Disease
    3. Multiple Cerebral Infarctions
    4. Huntington's Disease
  2. Obstructive (Incomplete except in Acute Hydrocephalus)
    1. Adult: Communicating (Extraventricular Blockage)
      1. Post-Subarachnoid Hemorrhage
      2. Post-Meningitis
      3. Idiopathic Normal Pressure Hydrocephalus
    2. Child: Noncommunicating (Interventricular Blockage)
      1. Aqueductal stenosis
      2. Masses compressing the Fourth Ventricle
        1. Cerebellar tumor
      3. Foramen magnum malformation
        1. Arnold-Chiari Malformation
        2. Dandy-Walker Syndrome

VI. Symptoms

  1. Headache
  2. Vomiting
  3. Limb weakness
  4. Incoordination

VII. Signs

  1. Child
    1. Rapid increase in Head Circumference
    2. Bulging Anterior Fontanelle
  2. Adult
    1. Classic Triad of Normal Pressure Hydrocephalus
      1. Dementia of subcortical type
      2. Gait disturbance
      3. Incontinence
    2. Abulia
    3. Papilledema
    4. Extraocular Movement deficit
      1. Eyes displaced downward or
      2. Loss of lateral gaze (Cranial Nerve 6 Palsy)

VIII. Imaging

  1. Cranial Ultrasound (Infants)
    1. Requires open Anterior Fontanelle
    2. Shows ventricular enlargement
  2. CT Head or MRI Head (preferred)
    1. Dilated ventricles

IX. Precautions

  1. Avoid Lumbar Puncture in acute obstructive Hydrocephalus
    1. Risk of Uncal Herniation

X. Diagnosis

  1. CSF Flow study
    1. Radioiodinated Serum Albumin or radioactive indium
    2. Identifies obstruction site

XI. Management: Surgical Shunt (Ventriculoperitoneal Shunt)

  1. See Ventriculoperitoneal Shunt
  2. Needs to be done before irreversible neurologic loss
  3. Predictors of shunt efficacy in Hydrocephalus
    1. Symptoms for less than 6 months
    2. Lumbar Puncture efficacious
      1. Lowers CSF Pressure <100 mm
      2. Improves gait

XII. Management: Non-surgical

  1. Indicated when surgery not possible
  2. Acetazolamide (Diamox): Decreases CSF production
    1. Child: 10-25 mg/kg/day PO divided tid
    2. Adult: 250 mg PO tid
  3. Serial Lumbar Puncture (Temporize until surgery)

XIII. Resources

  1. All About Normal Pressure Hydrocephalus
    1. http://www.allaboutnph.com

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