Changes in callosal angle and Evans index after shunt surgery in patients with idiopathic normal pressure hydrocephalus.

ABSTRACT

BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is a disease characterized by gait disturbance, cognitive impairment and urinary incontinence. For those patients who do not respond to shunt surgery, it lacks objective radiological findings for the diagnosis of shunt malfunction. Here we aimed to evaluate whether Evans index and callosal angle change during a prospective long-term follow-up of patients with iNPH submitted to shunt surgery. METHODS: Clinical (NPH Japanese Scale) and radiological (Evans index, callosal angle) data were collected pre- and postoperatively (3, 6, 12 months) in 19 patients with iNPH. Imaging tests were evaluated by the same neuroradiologist during the follow-up. RESULTS: Patients had lower scores on NPH Japanese Scale over time (p< 0.001). There was no significant difference among Evans index values during the follow-up (p= 0.24). Preoperative average callosal angle was 72 ± 15, which increased to 91 ± 18 in 6 months (p= 0.003). CONCLUSIONS: In this sample, patients with iNPH submitted to a programmable valve shunt had an increase in callosal angle concomitant to neurological improvement. Evans index did not change during follow-up.