Hydrocephalus

Aka: Hydrocephalus, Chronic Hydrocephalus, Acute Hydrocephalus, Communicating Hydrocephalus, Obstructive Hydrocephalus, Noncommunicating Hydrocephalus

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II. Definitions

  1. Hydrocephalus
    1. Abnormal increase in intracranial Cerebrospinal Fluid (CSF) volume and Intracranial Pressure (ICP)
    2. Caused by impaired CSF flow (noncommunicating, obstructive) or impaired absorption (communicating)
  2. Acute Hydrocephalus
    1. Rapid CSF accumulation results in sudden increase in Intracranial Pressure (e.g. infection, CNS Hemorrhage, shunt malfunction)
    2. Neurologic Emergency
    3. Complete Obstructive Hydrocephalus
  3. Chronic Hydrocephalus
    1. Gradual CSF accumulation and compensatory ventriculomegaly (e.g. Normal Pressure Hydrocephalus)
    2. May cause longterm cognitive dysfunction and Dementia
  4. Hydrocephalus ex vacuo
    1. Ventricles appear enlarged due to severe cerebral atrophy
    2. Not a true Hydrocephalus

III. Pathophysiology

  1. See Cerebral Ventricle
  2. See Cerebrospinal Fluid

IV. Risk Factors

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

V. Causes

  1. Hydrocephalus ex vacuo
    1. Ventricles appear enlarged due to severe cerebral atrophy (not a true Hydrocephalus)
    2. Causes
      1. Alzheimer's Disease
      2. Pick's Disease
      3. Multiple Cerebral Infarctions
      4. Huntington's Disease
  2. Communicating Hydrocephalus (adults or children)
    1. Impaired extra-ventricular CSF absorption at arachnoid granulations, basal cisterns
    2. Causes
      1. Post-Subarachnoid Hemorrhage
      2. Post-Meningitis
      3. Normal Pressure Hydrocephalus
  3. Non-Communicating Hydrocephalus (Interventricular obstruction, primarily children)
    1. Causes
      1. Aqueductal stenosis
      2. CSF Shunt Malfunction
      3. Incomplete Magendie or Luschka foramina development
      4. Masses compressing the Fourth Ventricle
        1. Cerebellar tumor
      5. Foramen magnum malformation
        1. Arnold-Chiari Malformation
        2. Dandy-Walker Syndrome
    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
  4. Venous Drainage Obstruction
    1. Cerebral Venous Sinus Thrombosis (Sagittal, Lateral)
      1. Aseptic (Hypercoagulable state)
      2. Septic (Otitis Media, Mastoiditis)
    2. Bilateral radical neck dissection (Jugular Vein cut)
    3. Superior Vena Cava Syndrome
    4. Increased Right Heart Pressure (Cor Pulmonale)

VI. Symptoms: Acute Hydrocephalus

  1. Headache
  2. Nausea and Vomiting
  3. Limb weakness
  4. Incoordination
  5. Confusion
  6. Tinnitus

VII. Signs: Acute Hydrocephalus

  1. Infant (esp. Non-Communicating Hydrocephalus)
    1. Rapid increase in Head Circumference (>97%)
    2. Bulging Anterior Fontanelle
    3. Poor feeding
    4. Vomiting
    5. Failure to Thrive
    6. Impaired upward gaze (sunset sign)
    7. Irritability
    8. Decreased Level of Consciousness
  2. Older Children and Adults (esp. Communicating Hydrocephalus)
    1. Acute confusion
    2. Altered Level of Consciousness or somnolent
    3. Papilledema
    4. Extraocular Movement deficit
      1. Eyes displaced downward (sunset sign) or
      2. Loss of lateral gaze (Cranial Nerve 6 Palsy)
  3. Cushing Triad (severe ICP increase or impending Brainstem Herniation)
    1. Hypertension
    2. Bradycardia
    3. Irregular respirations

VIII. Signs: Chronic Hydrocephalus

  1. Abulia
    1. Severe lack of willpower, motivation, and initiative
    2. Normal altertness and cognition
  2. Classic Triad of Normal Pressure Hydrocephalus
    1. Dementia of subcortical type
    2. Gait disturbance
    3. Incontinence

IX. Differential Diagnosis

  1. See Increased Intracranial Pressure Causes

X. Imaging

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

XI. Precautions

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

XII. Diagnosis

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

XIII. Management: Acute Hydrocephalus

  1. See Increased Intracranial Pressure in Closed Head Injury
  2. See Ventriculoperitoneal Shunt Malfunction

XIV. Management: Chronic Hydrocephalus

  1. Surgical Shunt (Ventriculoperitoneal Shunt)
    1. See Ventriculoperitoneal Shunt
    2. Perform 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 mmHg
        2. Improves gait
  2. Non-surgical
    1. Indicated when surgery not possible
    2. Acetazolamide (Diamox): Decreases CSF production
      1. Child: 10-25 mg/kg/day orally divided three times daily
      2. Adult: 250 mg orally three times daily
    3. Serial Lumbar Puncture
      1. Temporize until surgery

XV. References

  1. Jundoria, Dave, Hoag and Lopez (2026) Crit Dec Emeg Med 40(5): 4-11

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