Predictors of the need for cerebrospinal fluid diversion in patients with myelomeningocele.

OBJECT

Many patients with myelomeningocele (MMC) develop hydrocephalus, and most will undergo CSF diversion. The goal of this retrospective study was to determine whether there was a change in the shunt rate over the 7 consecutive years of the study. The authors will also identify the criteria used to determine the need for shunt placement.

METHODS

During a 7-year period, 73 patients underwent MMC closure at Arkansas Children's Hospital. The shunt rate for each year was calculated. Clinical characteristics were evaluated, including apneic and bradycardic spells, CSF leak, level of the MMC, head circumference, and rate of head growth. In addition, radiological images were reviewed, and the frontooccipital horn ratio (FOHR), ventricular index (VI), and thalamooccipital distance (TOD) were calculated. Comparisons were made between those patients who underwent shunt placement and those who did not.

RESULTS

One patient was excluded due to death in the perinatal period. Of the 72 remaining patients, 54 (75%) underwent placement of a ventriculoperitoneal shunt. This rate did not change significantly over time. Between the cohorts with and without a shunt there was no significant difference in age, sex, or race. There was no significant difference in apneic episodes or bradycardic episodes. There was a statistically significant difference in fontanelle characteristics, head circumference at birth, and rate of head growth. Patients who required CSF diversion had a mean head growth of 0.32 cm/day compared with those who did not receive a shunt (0.13 cm/day; p < 0.05). All radiological parameters were found to be statistically significant.

CONCLUSIONS

In this study, several classic indicators of hydrocephalus in the neonate were not found to be significantly associated with the need for CSF diversion. Fontanelle characteristics, head circumference at birth, and head growth velocity were associated with the need for shunt placement. Imaging information including the VI, TOD, and FOHR are statistically significant measures to evaluate prior to placement of a ventriculoperitoneal shunt. The optimal patient with MMC for CSF diversion will have full to tense fontanelle, increasing head circumference of more than 3 mm/day, and radiological evidence of an elevated VI, TOD, and/or FOHR.