What are the initial assessment and management steps for a patient with possible obstructive hydrocephalus?

Assessment and Management of Obstructive Hydrocephalus

Initial Clinical Assessment

Patients with suspected obstructive hydrocephalus require immediate neuroimaging with non-contrast CT scan to confirm the diagnosis, followed by urgent neurosurgical consultation. 1

Key History and Physical Examination Findings

The clinical presentation depends on the rapidity of onset and underlying etiology 2:

Acute Presentation:

• Sudden severe headache (particularly in subarachnoid hemorrhage or cerebellar stroke contexts) 1
• Rapid deterioration in level of consciousness - progressing from wakefulness to drowsiness to coma 3
• Nausea and vomiting 1, 3
• Respiratory insufficiency requiring immediate intubation 4

Subacute/Chronic Presentation:

• Gait disturbance (ataxia, broad-based gait) 1
• Urinary incontinence 1
• Altered mental status or dementia 1
• Cranial neuropathies 1
• Headache with postural component 1

Neurological Examination Priorities

Perform serial neurological examinations focusing on 1, 4:

• Glasgow Coma Scale (GCS) score - deterioration indicates need for immediate intervention 1, 3
• Pupillary responses - assess for signs of herniation
• Motor examination - looking for focal deficits or posturing
• Gait assessment - when patient condition permits 1
• Cranial nerve examination - particularly for brainstem compression signs 1

Diagnostic Imaging Algorithm

First-Line Imaging

Non-contrast CT scan of the head should be performed immediately upon arrival 1:

• Identifies ventriculomegaly (not due to cerebral atrophy) 1
• Detects transependymal edema - hallmark of acute hydrocephalus 1
• Distinguishes communicating from non-communicating hydrocephalus 1
• Identifies underlying cause (mass, hemorrhage, infarction) 1

Advanced Imaging

Contrast-enhanced MRI of brain and spine should be undertaken in all patients shortly after presentation 1:

Brain MRI Protocol 1:

• T2-weighted sequences at 4-5mm thickness
• FLAIR (axial or coronal) at 4-5mm thickness
• T2* GRE or SWI (axial) at 2-5mm thickness
• Pre- and post-contrast 3D T1-weighted volumetric acquisitions

Spine MRI Protocol (when indicated) 1:

• Fat-suppressed T2-weighted sequences (STIR)
• High-resolution heavily T2-weighted 3D sequences (CISS, FIESTA, bFFE)
• Sagittal and axial T2-weighted at 3-4mm thickness

Phase-contrast and T2-weighted cinematic MRI provide valuable insights into CSF dynamics and can identify specific obstructive lesions like aqueductal webs 5

Severity Assessment Tools

Use validated scales to determine severity 1:

• Glasgow Coma Scale (GCS) 1, 3
• World Federation of Neurological Surgeons (WFNS) scale 1
• Hunt and Hess scale 1
• Fisher Scale (for subarachnoid hemorrhage) 1
• NIHSS 1

Lumbar Puncture Considerations

Opening pressure measurement at lumbar puncture can be suggestive of hydrocephalus 1:

• However, ventricular fluid pressure may be normal in some cases and this finding alone should not exclude the diagnosis 1
• Given the low risk of lumbar puncture when hydrocephalus is present, this evaluation should be undertaken as part of neurosurgical collaboration 1

Immediate Management Steps

Medical Stabilization

Before transfer or definitive treatment 1, 6:

• Elevate head of bed to 30 degrees 4
• Administer mannitol 0.25 to 2 g/kg IV over 30-60 minutes for reduction of intracranial pressure 6, 3
• Osmotic diuretics and hyperventilation provide only transient benefit 4
• Intubate immediately if respiratory insufficiency develops 4

Transfer Considerations

Patients should be transferred urgently to a center with neurosurgical expertise 1, 4:

• Initiate coagulopathy reversal and blood pressure control before transfer to avoid treatment delays 1
• However, do not delay transfer if it is the clinical priority 1
• Transfer within 48 hours if patient cannot care for themselves but has help 1
• Emergency admission if patient cannot care for themselves and lacks help 1

Surgical Management Algorithm

First-Line Surgical Intervention

Emergency ventriculostomy (external ventricular drain placement) is the initial surgical treatment 1, 4:

• Effective in isolation for relieving symptoms in many cases 1, 4
• Particularly effective even in acute ischemic cerebellar stroke 1
• Risk of upward herniation can be minimized with conservative CSF drainage 1, 4

Specific indications for urgent EVD placement 1:

• Aneurysmal SAH with CT evidence of hydrocephalus that is clinically symptomatic 1
• Clinical hydrocephalus defined as worsening examination attributable to acute hydrocephalus 1

Second-Line Surgical Intervention

If ventriculostomy fails to improve neurological function, proceed to decompressive suboccipital craniectomy 1, 4:

• Indicated when cerebellar infarction causes neurological deterioration from brainstem compression despite maximal medical therapy 1, 4
• 85% of patients progressing to coma die without intervention, but half have good outcomes with decompression 4
• Obstructive hydrocephalus should be treated concurrently with ventriculostomy when deemed safe 1, 4

Endoscopic Approaches

In centers with neuro-endoscopic expertise, endoscopic third ventriculostomy (ETV) is the preferred procedure for certain cases of obstructive hydrocephalus 4, 5:

• Particularly useful for aqueductal stenosis or webs 5
• Restores physiologic CSF flow without need for permanent shunt 5

Monitoring Requirements

Patients require intensive monitoring for at least 48 hours 4, 7:

• Regular neurological checks by staff trained in neurological assessment 1
• Monitoring for signs of increased intracranial pressure 4, 7
• Management of drainage system (if EVD placed) 4
• Monitoring for potential complications including infection, hemorrhage, and shunt malfunction 4, 7

The highest-risk period for neurological decline is within the first 12 hours, with deterioration becoming uncommon after 48 hours 1

Critical Pitfalls to Avoid

• Do not delay neurosurgical consultation - patients with SAH and hydrocephalus should be assessed without delay due to high early rebleeding risk 1
• Do not assume normal ventricular pressure excludes hydrocephalus - pressure may be normal in some cases 1
• Do not perform ventriculostomy without considering upward herniation risk - use conservative drainage techniques 1, 4
• Do not delay transfer to obtain all imaging if patient is deteriorating - prioritize access to neurosurgical care 1
• Do not rely solely on medical management (mannitol, hyperventilation) as these provide only transient benefit 4