Delayed symptom progression after ventriculoperitoneal shunt placement for normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is generally treated with ventriculoperitoneal shunts (VPS), with improved symptoms in the majority of patients. We performed a retrospective chart review study in order to describe patterns of, and risk factors for, delayed symptom progression after initially successful VPS placement. 69 consecutive patients underwent VPS placement for NPH, and were followed for a minimum of 12 months postoperatively. 55 patients (80%) had objective improvement in their NPH symptoms after surgery. Of these, 27 patients (49%) developed delayed deterioration of at least one of their NPH symptoms, at a mean of 28.3 months postoperatively (range, 3-77). 1 of the 27 patients was found to have shunt malfunction; 19 had specific clinical or imaging evidence of shunt function. 6/19 patients had transient improvement in their symptoms (lasting 30 days or more) after adjustment of their programmable shunt valves (32%), although symptoms in all of these patients later worsened. During a mean follow up period of 44.4 months (range, 15-87), 12 patients (44%) received other neurological diagnoses felt to at least partially explain their symptoms. Increased patient age was associated with likelihood of delayed symptom progression. We conclude that delayed symptom progression is common after VPS placement for NPH, including after initial symptom improvement; that symptom progression can often be temporarily palliated by shunt valve pressure adjustment; and that older patients are more likely to experience delayed symptom progression. We suggest that patients and their families be counselled accordingly before surgery.