Who Is a Likely Candidate for Shunting?
The answer to this question still eludes neurologists and neurosurgeons. Many tests and criteria have been proposed, but unfortunately, no one single factor is reliable in predicting success from a shunt. The following findings are generally associated with a better prognosis:
- The onset of gait disturbance as the first and most prominent symptom
- A known cause for NPH, for example, trauma or hemorrhage
- Removal of spinal fluid via lumbar puncture or lumbar catheter gives dramatic, temporary relief of symptoms
- ICP or spinal fluid pressure monitoring shows an abnormal range or pattern of spinal fluid pressure or an elevated CSF outflow resistance
- There is minimal evidence of disease of the small blood vessels nourishing the brain
Because some patients with NPH have additional medical or neurological problems, it is important for patients, their families and their neurosurgeons to discuss their expectations of shunt surgery. Does 'success' mean that the patient will regain the levels of motor skill or mental ability they had before the symptoms presented themselves? Does it mean that the condition will not worsen? Or does it mean something else? The definition of success must be individualized, and it is important to know that it is possible for any or all of the hydrocephalus symptoms to improve. One way to evaluate the success of shunt surgery is to consider whether it has reduced the disabilities that were present before surgery and increased the patient's functional abilities.
Although complete recovery is often hoped for, it is not often seen, and many patients and their families are satisfied when shunt surgery results in less disability or dependence than the patient had before surgery. Patients, their families and their physicians need to be supportive and hopeful, but they should also know the possible complications, risks and realities of shunting.
Not all patients with enlarged ventricles need treatment. Some patients with enlarged ventricles have no symptoms and no neurologic deficits at all, even when evaluated by neurologists and neurosurgeons who specialize in hydrocephalus. This is a condition often called 'compensated hydrocephalus.' Patients who have compensated hydrocephalus cannot be 'made better' by treating the hydrocephalus, and in such circumstances, there are no benefits of treatment that would offset the potential risks of treatment (see below). Patients with compensated hydrocephalus may, however, develop symptoms later in their lives, and can benefit from treatment of hydrocephalus at that time. Therefore, it is important for patients with compensated hydrocephalus to see a neurologist or neurosurgeon periodically to assess whether subtle symptoms are developing.