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Normal Pressure Hydrocephalus
Aka: Normal Pressure Hydrocephalus
- See Also
- Hydrocephalus
- Pathophysiology
- See Cerebrospinal Fluid
- Defined as communicating Hydrocephalus
- No obstructive mass
- Results from decreased CSF absorption
- Due to scarring or fibrosis of arachnoid granulations
- Pressure builds within ventricles
- Baseline pressure higher but in normal range
- CSF production decreases
- Ventricles distend
- Stretch nerve fibers
- Compress periventricular tissue including vessels
- Brain parenchymal ischemia
- Causes
- Idiopathic fibrosis in most cases
- Contributing causes in some cases
- Subarachnoid Hemorrhage
- Head Injury
- Meningitis
- Symptoms and signs
- Classic triad (Positive Predictive Value: 65%)
- Dementia (Wacky)
- Gait instability (Wobbly)
- Urinary Incontinence (Wet)
- Gait instability (Gait Apraxia)
- Most common initial symptom
- Short shuffling steps (feet glued to floor)
- Wide based, slow ambulation
- Urinary Incontinence
- Urinary urgency
- Urodynamics: Detrussor muscle ineffective contraction
- Subcortical Dementia
- Late finding, and least responsive to shunting
- Findings
- Inattention
- Recall latency (but memory is accurate)
- Loss of spontaneity
- Cortical findings are not seen in NPH Dementia
- No difficulty with word formation (Aphasia)
- Able to interpret stimuli (Agnosia)
- No difficulty with sequential tasks (Apraxia)
- Differential Diagnosis
- See Hydrocephalus
- See Overflow Incontinence
- See Dementia
- See Parkinson's Disease
- Radiology
- MRI Head
- Ventriculomegaly
- Cerebral parenchyma preserved
- Contrast with Alzheimer's Disease
- Medial hippocampus and Temporal Lobe preserved
- Contrast with Alzheimer's Disease
- Cine MRI (CSF flow imaging)
- Turbulent posterior Third Ventricle flow
- Turbulent Aqueduct of Sylvius flow
- Radionuclide cisternography
- Used to evaluate for communicating Hydrocephalus
- Diagnostics
- Routine Lumbar Puncture
- Evaluates differential diagnosis
- Normal CSF Exam
- Normal CSF Protein
- Normal CSF Glucose
- CSF Opening Pressure <200 mm H2O
- High volume Lumbar Puncture
- Assess symptoms before/after removing 30-60 ml CSF
- Predictive of response to shunting
- Prolonged lumbar drainage
- CSF removed over 3-5 days via pump
- Predictive of response to shunting
- Intracranial Pressure monitoring
- May identify intermittent spikes in CSF Pressure
- CSF outflow
- Saline infused 0.5-5 ml/min via Lumbar Puncture
- Intracranial Pressure measured via ventriculostomy
- Observe for elevated outflow resistance
- May predict shunting response
- Management: Ventriculoperitoneal Shunting
- Description
- Catheter in Lateral Ventricle
- Cap and valve placed below scalp
- Tubing tunneled SQ from valve to Abdomen
- CSF diverted from ventricle to peritoneum
- Efficacy
- Variable based on patient selection
- Predictors of good response to shunting
- Patients with known NPH etiology do best
- Symptoms present only for short time
- No Dementia or mild Dementia present
- Diagnostics predictive of good response
- High volume Lumbar Puncture
- Prolonged lumbar drainage
- References
- Vanneste (2000) J Neurol 247:5-14 [PubMed]
- Verrees (2004) Am Fam Physician 70:1071-86 [PubMed]