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NeuroLogic - Hydrocephalus: Common Symptoms, Rare Disorder
Hydrocephalus: Common Symptoms, Rare Disorder
Date: September 1, 2007
An energetic octogenarian in Philadelphia returned to college to earn the degree that had eluded her earlier in life. Soon, though, the woman started having problems with balance and resorted to walking with a cane. Mild dementia made it impossible to keep up in class.
When brain imaging revealed ballooning ventricles, the patient was referred to Johns Hopkins for a comprehensive evaluation and diagnosed with adult hydrocephalus, or normal pressure hydrocephalus. A shunt was surgically placed to drain off excess cerebral spinal fluid.
The patient’s walking improved, her cognitive scores jumped, and soon she was back in the classroom again. “There was no question about it,” says neurologist David Solomon. “She had NPH, she got the right treatment, and she got a great result.”
Solomon and neurologist Abhay Moghekar are the new leaders of the hydrocephalus program, along with veteran team member neurosurgeon Daniele Rigamonti, who established the service six years ago and has since operated on no fewer than 600 patients.
Treating hydrocephalus is especially gratifying, they say. It’s one of the few instances in which dementia can actually be reversed. But the devil is in the diagnosis—and in determining the best candidates for the shunt. “Fortunately,” says Rigamonti, “we bring to the table a deep understanding of the symptomatology and of the differential diagnosis.”
Solomon specializes in balance disorders; Moghekar, in cognitive disorders. Because gait problems and dementia are two in the triad of hydrocephalus symptoms (the third is incontinence), these two are particularly qualified to distinguish the characteristics of NPH from the more common disorders it mimics, Parkinson’s and Alzheimer’s.
With both hydrocephalus and Parkinson’s, for example, patients tend to shuffle. Strides are small; the heel doesn’t clear the toe. “But only patients with NPH walk with feet splayed outward and with an arm swing,” says Solomon. “Gait disturbance is an initial manifestation of hydrocephalus. If there are problems with gait, don’t wait for the other two symptoms in the triad to follow.”
One way to determine if a patient is a good candidate for a shunt is to remove 40 to 50 milliliters of CSF all at once via lumbar puncture. “While this test is superior to clinical examination alone,” says Moghekar, “it has a low sensitivity of only 26 to 61 percent, meaning that you will miss approximately 60 percent of patients who could have potentially benefited from a shunt.”
To avoid this problem, Hopkins patients are admitted for rigorous evaluation during which more than 300 milliliters of CSF is drained over a period of three days. “This is a highly sensitive test with a positive, predictive value of between 80 and 100 percent,” says Moghekar. Gait and cognitive skills are tested quantitatively before and after so that physicians can make objective assessments.
In part because the shunt is permanent, patients sometimes resist the surgery. Selvin Madow (pictured above), who developed hydrocephalus following a head injury, put it off for a couple of years until his wife implored him to do something about his peculiar gait and other symptoms.
In fact, studies conducted on the large cohort of hydrocephalus patients treated here have shown the value of timely treatment. “At a certain point, some irreversible changes occur,” says Rigamonti. “If you have a patient whose symptoms started more than five years earlier, chances are you may recover only 50 to 60 percent. But if symptoms are of a shorter duration, you have a window of opportunity that allows the patient to recover almost completely.”
To refer a patient: 440-955-7482