Laboratory Studies
Laboratory studies in the assessment of posttraumatic hydrocephalus (PTH) include the following:
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Urine analysis and culture - Evaluate for urinary tract infections
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Complete blood count (CBC) with differential - Evaluate for infection and anemia
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Metabolic profile - Evaluate for electrolyte abnormalities, including syndrome of inappropriate secretion of antidiuretic hormone (SIADH), cerebral salt wasting, calcium deficiency, hypoglycemia, hyperglycemia, and encephalopathy (uremic or hepatic)
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Thyroid-stimulating hormone (TSH), free T4 - Evaluate for hypothyroidism or hyperthyroidism
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Arterial blood gas level - Assess oxygenation and acid/base balance
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Serum medication levels - Measure medication levels if toxicity suspected
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CSF analysis - Evaluate for infectious etiologies, autoimmune disease, and certain cancers
Imaging Studies
See the list below:
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Noncontrast CT scan of the brain is one of the most commonly used diagnostic modalities.
The progressive enlargement of the ventricular system shown on repeat computed tomography (CT) scans is the key to the diagnosis of PTH. [7]
CT scans may show enlarged lateral ventricles, effaced cerebral sulci, and dilation on ventricles proximal to an obstruction. [5]
Periventricular edema may occur in white matter, particularly around the frontal horns. [5]
Sulcal enlargement with ventricular enlargement suggests atrophy and hydrocephalus ex vacuo rather than hydrocephalus. [5]
Large cisterns and focal regions of encephalomalacia suggest atrophy. [6, 27]
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Magnetic resonance imaging (MRI) is another method of diagnostic evaluation. [28]
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MRI is more useful in the evaluation of injury to structures in the posterior fossa, including cerebral aqueduct stenosis and cerebellar tonsil herniation. [29]
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It is the neuroimaging study of choice in patients with NPH. [29]
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MRI may be more useful than CT scanning in the identification of other neurologic disorders, especially cerebrovascular disease. [30]
Mazzini studied another imaging technique, single-photon emission CT (SPECT). [8] Mazzini found that SPECT had higher sensitivity than MRI or CT scanning in the demonstration of temporal lobe abnormality secondary to PTH.
Other Tests
See the list below:
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Radionuclide cisternography: [5]
Radioiodinated serum albumin (RISA) injected into the subarachnoid space by way of lumbar puncture (LP) can normally be detected in the cisterna magna, basal cisterns, and subtentorial subarachnoid space within 6 hours, with little accumulation in the ventricular system. In NPH, RISA accumulates in the ventricular system with delayed pericerebral diffusion.
Cisternography is usually normal in hydrocephalus ex vacuo.
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Although debate exists, cisternography may be a useful adjunct to CT scanning of the brain.
Procedures
See the list below:
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CSF tap test
This test is an LP with manometry and CSF removal.
Imaging of the brain should be performed before initiating the LP. The risk of cerebral herniation associated with the LP is increased in patients with greatly elevated ICP.
The CSF tap test may be a useful predictor of the potential benefits of shunting. Kim (2005) found that symptomatic improvement after lumbar drainage has a significant role in predicting the result of shunting.
CSF pressure is normally 110 mm water. Shunting may help if the pressure is 135-275 mm water, and it does help if the pressure is greater than 275 mm water.
Cognitive and physical functions are assessed before and after the removal of 50 mL of CSF. Improvement suggests that shunting may be beneficial.
