Treatment of hydromyelia in spina bifida

Cavitation of the spinal cord (hydrosyringomyelia) seems to be common in spina bifida patients, although the overall clinical and radiological incidence has very rarely been analyzed. The real incidence of the condition is, in fact, difficult to assess as patients with this complication may remain relatively asymptomatic. The mechanisms accounting for the occurrence of hydrosyringomyelia in myelodysplasia are still a subject of debate. Similarly, the indications for the surgical treatment are still to be defined and its results to be assessed.

In this study, 142 patients with spina bifida were screened with magnetic resonance imaging (MRI) to determine the incidence of hydromyelia. Thirty-two patients presented a cavitating lesion on MRIs of which 18 were not a cause of symptoms and 14 were. Clinical characteristics of the lesions and their correlation to the radiological picture were analyzed. All the symptomatic children underwent surgical treatment. Outcomes were evaluated and correlated also with the MRI findings.

A correlation between the presence of symptomatology and the extension and/or dilation of the hydromyelia was observed. A significant relationship between the presence of symptoms and adequate control of associated hydrocephalus was also noted. No correlation was observed between the presence of hydromyelia and the level of the myelomeningocele or the degree of ventricular dilation in those cases that presented with hydrocephalus. The mean age at hydromyelia diagnosis for all patients affected was 3.9 years and, in particular, 4 years for those patients who presented with symptoms. A total of 15 operations were performed in the 14 symptomatic patients. Seven direct procedures were carried out to drain the hydromyelia: five hydroperitoneal shunt insertions and two hydrosubarachnoid shunting procedures. Eight indirect treatments were performed to eliminate the filling mechanism of the hydromyelia: five posterior fossa decompressions, two ventriculoperitoneal shunt revisions, and one spinal cord untethering procedure with terminal syringostomy. All patients improved postoperatively, except one who remained clinically stable at follow-up. This patient had undergone a posterior fossa decompression followed by a hydrosubarachnoid shunting procedure.

The incidence of syringohydromyelia is actually higher than that reported in the literature, although not all lesions are symptomatic. The radiological picture may be helpful in planning a more careful follow-up program for patients theoretically at risk for neurologic deterioration. Surgical treatment is possible with good results in the majority of cases and should be carried out as soon as possible before further deterioration occurs. Not all symptoms respond equally to treatment. Generally, improvement of clinical status correlates with a reduction in size of the hydromyelic cavity on MRI.