Normal pressure hydrocephalus: long-term outcome after shunt surgery

Background/objective: Little is known about the long-term clinical course and management of patients with normal pressure hydrocephalus (NPH) treated by cerebrospinal fluid (CSF) shunting. Methods: We retrospectively reviewed records of 55 patients diagnosed with idiopathic NPH (INPH) and treated with CSF shunts, all of whom were followed for more than 3 years after the original shunt surgery. At each annual follow-up visit, the patient was assessed by Folstein Mini Mental State Examination, detailed clinical evaluation of gait and assessment of headache, cognition, gait or urination, as assessed by the patient and relatives. Results: The mean duration of follow-up was 5.9 +/- 2.5 years. There was an overall sustained improvement among all symptoms. Gait showed the highest maintenance of improvement over baseline (83% at 3 years and 87% at the last analysed follow-up of 7 years), cognition showed intermediary improvement (84% and 86%, respectively), and urinary incontinence showed the least improvement (84% and 80%, respectively). Fifty-three percent of patients required shunt revisions. Indications for revision included shunt malfunction (87%), infection (10%) and change of shunt configuration (3%). Overall, 74% revisions resulted in clinical improvement. Conclusions: Clinical improvement of patients with NPH can be sustained for 5 - 7 years in some patients with NPH, even if shunt revision surgery is needed multiple times. With earlier diagnosis and treatment of NPH and the increasing lifespan of the ageing population, the need for long-term follow-up after shunt surgery for NPH may be greater than it was in the past. Monitoring, identification and treatment of shunt obstruction is a key management principle.