Factors influencing spinal canal stenosis in patients with long-term controlled hydrocephalus treated with cerebrospinal fluid shunt.

PURPOSE: Spinal canal stenosis (CS) occurs in patients with hydrocephalus who are treated with cerebrospinal fluid (CSF) shunting. The pathophysiology of CS comprises CSF overdrainage. We analyzed the incidence of CS and the factors causing it.

METHODS

Thirty-three patients who underwent ventriculoperitoneal shunt during childhood visited the Outpatient Department in Yamaguchi University Hospital in 2006. Diameters of spinal canal at C(4) were measured. Treatment procedure, age, and type of hydrocephalus in the patients with CS were compared with those without CS.

RESULTS

Of the 33 patients, 10 (30.3%) presented CS, and two (6.1%) were symptomatic. A low-pressure valve caused CS with a significantly higher incidence than a medium- or high-pressure valve (60.0% vs. 17.4%, P < 0.05). Although the difference was not significant, the average age of shunt insertion for a patient with CS was slightly less (0.87 +/- 0.99) than for a patient without CS (1.63 +/- 1.58). No differences in the CS incidence were observed between obstructive and communicating hydrocephalus.

CONCLUSION

In order to prevent CS, the hydrocephalus should be appropriately controlled by using a medium- or high-pressure valve until the diameter of the spinal canal reaches the required level. Adjustment of the programmable valve with the patient's growth should be ideal.