Normal Pressure Hydrocephalus: Diagnosis and New Approaches to Treatment

NPH is a chronic adult hydrocephalus characterized by gait deficit and, possibly, cognitive slowing and urinary urgency and incontinence. It is a disease of CSF circulation and parenchymal changes. Essential to the diagnosis of NPH are ventriculomegaly and gait disturbance, whereas cognitive and urinary problems also are seen often and, with gait impairment, constitute Adam's triad. The existence of other neurologic problems, such as cerebrvascular disease, does not eliminate the possibility of NPH but has a negative impact on the benefits of ventricular shunting. The diagnosis of NPH may be reinforced with ancillary tests, where the removal of several hundred milliliters of CSF over an extended period of time may be performed optimally through a lumbar drain. Other tests, including MRI with cine CSF flow study, CSF infusion studies, intracranial pressure monitoring, and cisternograms, may be useful in reinforcement of the diagnosis but may have little additional impact on diagnostic accuracy. Referral for an evaluation by an experienced neurosurgeon should be considered strongly if symptoms include gait impairment, unexplained by spinal disease or other progressive neurologic disorder, and ventriculomegaly as identified on either CT or MRI (ie, quadrant I patients). If ventriculomegaly exists, NPH still may be considered even in the context of other symptoms and comorbidities (such as spinal or vascular disease) and some of these patients also may undergo CSF drainage trial to evaluate potential improvement (quadrant II). Advancements in the technique and materials of CSF shunting and improvements in follow-up and postoperative CSF drainage have increased the possibility of benefit after treatment and reduced complications. Optimal treatment of NPH requires vigilant patient selection, meticulous surgical implantation, and careful follow-up with optimization. The failure to identify and treat these patients, however, results in a definite shortening of quality of life in the elderly population.