Diagnosing Normal Pressure Hydrocephalus (NPH)
Often times the cause of Normal Pressure Hydrocephalus
(NPH) cannot be determined. In a few cases it can be
associated with a previous head injury or surgery. The
best way to diagnose patients presenting with the triad
of symptoms is to have them referred to a neurosurgeon.
The first step to diagnosing NPH is a magnetic resonance
imaging (MRI) scan or a computed tomography (CT) scan
which can show the build-up of fluid, and a thorough
history and neurological assessment. An additional evaluation
by a qualified neurologist may also be recommended at
this time. If NPH is still suspected after the initial
neurosurgical consultation, a multidisciplinary team
including a physical therapist, a speech therapist,
and a neuropsychologist will evaluate the patient to
determine if a more invasive external lumbar drainage
test would impact the symptoms.
External lumbar drainage
New medical guidelines suggest that this test may help
determine which patients are most likely to benefit
from NPH treatment. The lumbar drain has been found
to be the best predictor of whether a patient will improve
through treatment or not. An inpatient procedure running
the course of 3-4 days, the external lumbar drain is
placed in the spine and a small volume of fluid is drained
daily from the back in order to reduce the amount of
CSF around the brain. Each day the patient’s gait
(ability to walk), cognitive processes (ability to think),
and incontinence will be measured and analyzed independently
by nurses, physical therapists, speech therapists, neuropsychologists,
and rehabilitation specialists. Any improvement in symptoms
with this procedure is highly suggestive that an operation
to insert a shunt would be beneficial.
In some patients, this test may be done on an outpatient
basis. External lumbar drainage is "simulated"
by performing a series of lumbar punctures at which
a relatively high volume of CSF is withdrawn.
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