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KembaraXtra-Emergency And Acute Medicine: Hydrocephalus
Basics
Description Hydrocephalus is an abnormal increase in cerebrospinal fluid (CSF) volume within the cranial cavity. Cerebral atrophy may also increase CSF volume but without elevated CSF pressure. Obstructive hydrocephalus is the most common form and results from blockage within the ventricular system or subarachnoid space, potentially causing rapid rises in intracranial pressure (ICP) leading to death or permanent brain injury. Nonobstructive hydrocephalus produces subacute symptoms and represents a potentially reversible cause of dementia. Hydrocephalus is also classified as communicating, where CSF flow is blocked after exiting the ventricles, and noncommunicating, where flow is blocked within ventricular pathways.
Etiology Obstructive hydrocephalus results from blockage at specific anatomic sites. Aqueduct of Sylvius obstruction is most common, causing dilation of the lateral and third ventricles with sparing of the fourth ventricle; causes include congenital stenosis, tumor, subarachnoid hemorrhage, postmeningitic scarring, or idiopathic disease. Foramen of Monro obstruction leads to dilation of one or both lateral ventricles. Obstruction at the foramina of Luschka and Magendie causes fourth ventricle blockage with subsequent dilation of the entire ventricular system. Subarachnoid space obstruction around the brainstem may occur after infection or subarachnoid hemorrhage, producing global ventricular dilation. Acute presentations are often due to CSF shunt malfunction, subarachnoid hemorrhage, or severe head trauma. Nonobstructive hydrocephalus, including normal pressure hydrocephalus, involves impaired CSF absorption with ventricular enlargement but no sustained intracranial hypertension and is sometimes termed chronic hydrocephalus. Pediatric hydrocephalus may be congenital or acquired and is commonly related to neonatal hemorrhage, congenital malformations, or postinfectious scarring.
Diagnosis
Signs and symptoms Obstructive hydrocephalus presents with headache, nausea, vomiting, decreased consciousness, urinary incontinence, ocular palsies, papilledema, visual loss, pupillary dilation, and Cushing response with hypertension and bradycardia. Pediatric patients may show a full fontanelle, irritability, lethargy, and elevated blood pressure. Slowly progressive obstruction may resemble nonobstructive hydrocephalus. Nonobstructive hydrocephalus presents with insidious dementia, somnolence, gait disturbance, urinary incontinence, impaired upward gaze, generalized weakness, and lethargy, typically without headache or papilledema.
Pediatric considerations Gradual CSF accumulation may cause craniomegaly, developmental delay, prominent scalp veins, and impaired upward gaze (setting-sun sign).
History Assess symptom onset, presence of a CSF shunt, headache, nausea or vomiting, weakness, confusion, visual changes, and urinary incontinence.
Physical exam Perform a complete neurologic examination including motor, sensory, reflexes, gait, and cranial nerves. Assess mental status and look for papilledema. Palpate any CSF shunt; inability to compress suggests distal malfunction, and failure to refill suggests proximal obstruction. In children, evaluate the anterior fontanelle.
Essential workup Noncontrast CT of the head assesses ventricular size and symmetry and helps identify hemorrhage, mass lesions, or cerebral edema.
Diagnosis tests and interpretation
Laboratory Lumbar puncture is performed only after CT and only for suspected nonobstructive causes; opening pressure may be elevated. Send CSF for routine studies if infection is suspected.
Imaging MRI provides detailed assessment of ventricular anatomy and improved detection of masses compared with CT.
Diagnostic procedures Lumbar puncture may be diagnostic or therapeutic in selected nonobstructive cases.
Differential diagnosis Acute ischemic stroke, intracranial hemorrhage, CNS infection, mass effect from tumor or hematoma, other causes of dementia or delirium, and toxic or metabolic encephalopathies.
Pediatric considerations Consider congenital anomalies such as Dandy–Walker malformation, Arnold–Chiari malformation, meningomyelocele, choroid plexus papilloma, or arachnoid villi dysfunction, as well as infections (rubella, CMV, toxoplasmosis, syphilis, bacterial meningitis), tumors of the posterior fossa, and intraventricular or subarachnoid hemorrhage.
Treatment
Prehospital Hydrocephalus cannot be definitively diagnosed in the field. Provide supplemental oxygen and airway support as needed. Transport with the head elevated to approximately 30° unless hypotension is present, in which case prioritize cerebral perfusion with fluid resuscitation.
Initial stabilization/therapy For signs of impending herniation, perform rapid-sequence intubation using agents such as etomidate or thiopental. Maintain controlled ventilation with PaCO₂ around 35 mm Hg and systolic blood pressure above 100 mm Hg in adults. Administer mannitol as indicated. In patients with CSF shunts and impending herniation, shunt pumping or controlled CSF drainage may be attempted to reduce pressure.
Emergency department management ED intervention is required for acute shunt malfunction or impending herniation. Definitive therapy involves shunt placement or revision or treatment of the underlying cause such as tumor. Symptoms of normal pressure hydrocephalus may transiently improve after removal of 20–30 mL of CSF via lumbar puncture. Acute obstructive hydrocephalus from intraventricular hemorrhage may require ventriculostomy. Provide sedation for agitated or intubated patients, maintain head elevation unless hypotensive, consider mannitol, and use seizure prophylaxis when appropriate.
Medication Atropine 0.02 mg/kg IV (max 0.1 mg), etomidate 0.2–0.3 mg/kg IV, lidocaine 1 mg/kg IV, mannitol 0.5–1.5 g/kg IV, rocuronium 0.6 mg/kg IV, succinylcholine 1–1.5 mg/kg IV, vecuronium 0.1 mg/kg IV, fosphenytoin 15–20 mg/kg loading dose.
Follow-up and disposition
Admission criteria Evidence of increased ICP or suspected shunt malfunction.
Discharge criteria Selected patients with presumed normal pressure hydrocephalus and no acute findings may be discharged with close follow-up.
Issues for referral Early neurosurgical consultation is essential for acute obstructive hydrocephalus or shunt malfunction; transfer should be considered if neurosurgical care is unavailable, with airway secured when indicated.
Follow-up recommendations Stable patients require prompt follow-up with neurology and/or neurosurgery.
Key points Lumbar puncture is contraindicated in obstructive hydrocephalus due to herniation risk. Rapid head growth in children should prompt evaluation for hydrocephalus. Any neurologic complaint in a patient with a CSF shunt should raise concern for shunt malfunction.
Basics
Description Hydrocephalus is an abnormal increase in cerebrospinal fluid (CSF) volume within the cranial cavity. Cerebral atrophy may also increase CSF volume but without elevated CSF pressure. Obstructive hydrocephalus is the most common form and results from blockage within the ventricular system or subarachnoid space, potentially causing rapid rises in intracranial pressure (ICP) leading to death or permanent brain injury. Nonobstructive hydrocephalus produces subacute symptoms and represents a potentially reversible cause of dementia. Hydrocephalus is also classified as communicating, where CSF flow is blocked after exiting the ventricles, and noncommunicating, where flow is blocked within ventricular pathways.
Etiology Obstructive hydrocephalus results from blockage at specific anatomic sites. Aqueduct of Sylvius obstruction is most common, causing dilation of the lateral and third ventricles with sparing of the fourth ventricle; causes include congenital stenosis, tumor, subarachnoid hemorrhage, postmeningitic scarring, or idiopathic disease. Foramen of Monro obstruction leads to dilation of one or both lateral ventricles. Obstruction at the foramina of Luschka and Magendie causes fourth ventricle blockage with subsequent dilation of the entire ventricular system. Subarachnoid space obstruction around the brainstem may occur after infection or subarachnoid hemorrhage, producing global ventricular dilation. Acute presentations are often due to CSF shunt malfunction, subarachnoid hemorrhage, or severe head trauma. Nonobstructive hydrocephalus, including normal pressure hydrocephalus, involves impaired CSF absorption with ventricular enlargement but no sustained intracranial hypertension and is sometimes termed chronic hydrocephalus. Pediatric hydrocephalus may be congenital or acquired and is commonly related to neonatal hemorrhage, congenital malformations, or postinfectious scarring.
Diagnosis
Signs and symptoms Obstructive hydrocephalus presents with headache, nausea, vomiting, decreased consciousness, urinary incontinence, ocular palsies, papilledema, visual loss, pupillary dilation, and Cushing response with hypertension and bradycardia. Pediatric patients may show a full fontanelle, irritability, lethargy, and elevated blood pressure. Slowly progressive obstruction may resemble nonobstructive hydrocephalus. Nonobstructive hydrocephalus presents with insidious dementia, somnolence, gait disturbance, urinary incontinence, impaired upward gaze, generalized weakness, and lethargy, typically without headache or papilledema.
Pediatric considerations Gradual CSF accumulation may cause craniomegaly, developmental delay, prominent scalp veins, and impaired upward gaze (setting-sun sign).
History Assess symptom onset, presence of a CSF shunt, headache, nausea or vomiting, weakness, confusion, visual changes, and urinary incontinence.
Physical exam Perform a complete neurologic examination including motor, sensory, reflexes, gait, and cranial nerves. Assess mental status and look for papilledema. Palpate any CSF shunt; inability to compress suggests distal malfunction, and failure to refill suggests proximal obstruction. In children, evaluate the anterior fontanelle.
Essential workup Noncontrast CT of the head assesses ventricular size and symmetry and helps identify hemorrhage, mass lesions, or cerebral edema.
Diagnosis tests and interpretation
Laboratory Lumbar puncture is performed only after CT and only for suspected nonobstructive causes; opening pressure may be elevated. Send CSF for routine studies if infection is suspected.
Imaging MRI provides detailed assessment of ventricular anatomy and improved detection of masses compared with CT.
Diagnostic procedures Lumbar puncture may be diagnostic or therapeutic in selected nonobstructive cases.
Differential diagnosis Acute ischemic stroke, intracranial hemorrhage, CNS infection, mass effect from tumor or hematoma, other causes of dementia or delirium, and toxic or metabolic encephalopathies.
Pediatric considerations Consider congenital anomalies such as Dandy–Walker malformation, Arnold–Chiari malformation, meningomyelocele, choroid plexus papilloma, or arachnoid villi dysfunction, as well as infections (rubella, CMV, toxoplasmosis, syphilis, bacterial meningitis), tumors of the posterior fossa, and intraventricular or subarachnoid hemorrhage.
Treatment
Prehospital Hydrocephalus cannot be definitively diagnosed in the field. Provide supplemental oxygen and airway support as needed. Transport with the head elevated to approximately 30° unless hypotension is present, in which case prioritize cerebral perfusion with fluid resuscitation.
Initial stabilization/therapy For signs of impending herniation, perform rapid-sequence intubation using agents such as etomidate or thiopental. Maintain controlled ventilation with PaCO₂ around 35 mm Hg and systolic blood pressure above 100 mm Hg in adults. Administer mannitol as indicated. In patients with CSF shunts and impending herniation, shunt pumping or controlled CSF drainage may be attempted to reduce pressure.
Emergency department management ED intervention is required for acute shunt malfunction or impending herniation. Definitive therapy involves shunt placement or revision or treatment of the underlying cause such as tumor. Symptoms of normal pressure hydrocephalus may transiently improve after removal of 20–30 mL of CSF via lumbar puncture. Acute obstructive hydrocephalus from intraventricular hemorrhage may require ventriculostomy. Provide sedation for agitated or intubated patients, maintain head elevation unless hypotensive, consider mannitol, and use seizure prophylaxis when appropriate.
Medication Atropine 0.02 mg/kg IV (max 0.1 mg), etomidate 0.2–0.3 mg/kg IV, lidocaine 1 mg/kg IV, mannitol 0.5–1.5 g/kg IV, rocuronium 0.6 mg/kg IV, succinylcholine 1–1.5 mg/kg IV, vecuronium 0.1 mg/kg IV, fosphenytoin 15–20 mg/kg loading dose.
Follow-up and disposition
Admission criteria Evidence of increased ICP or suspected shunt malfunction.
Discharge criteria Selected patients with presumed normal pressure hydrocephalus and no acute findings may be discharged with close follow-up.
Issues for referral Early neurosurgical consultation is essential for acute obstructive hydrocephalus or shunt malfunction; transfer should be considered if neurosurgical care is unavailable, with airway secured when indicated.
Follow-up recommendations Stable patients require prompt follow-up with neurology and/or neurosurgery.
Key points Lumbar puncture is contraindicated in obstructive hydrocephalus due to herniation risk. Rapid head growth in children should prompt evaluation for hydrocephalus. Any neurologic complaint in a patient with a CSF shunt should raise concern for shunt malfunction.
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