Selective dorsal root rhizotomy is performed for relief of spasticity in children with cerebral palsy. Postoperative pain relief can be provided by intrathecal morphine administered at the time of the procedure. We sought to define an optimal dose of intrathecal morphine in children undergoing selective rhizotomy, through a randomized, double-blinded prospective trial. After institutional approval and parental written informed consent, 27 patients, ages 3-10 years, were randomized to receive 10, 20, or 30 micrograms.kg-1 (Groups A, B, and C, respectively) of preservative-free morphine administered intrathecally by the surgeon after dural closure. Postoperatively, vital signs, pulse oximetry, and pain intensity scores were recorded hourly for 24 hr. Supplemental intravenous morphine was administered postoperatively according to a predetermined schedule based on pain scores. There was considerable individual variability in the time to initial morphine dosing and cumulative supplemental morphine dose. Time to first supplemental morphine dose was not different between groups. When compared to Groups A and B, cumulative 6-hr supplemental morphine dose was significantly lower in Group C (38.6 +/- 47 micrograms versus 79.1 +/- 74 and 189.6 +/- 126 for Groups A and B, respectively). By 12 hr, cumulative supplemental morphine dose was similar in Groups A and C. Group B consistently had a higher supplemental dose requirement than Groups A and C at 6, 12, and 18 hr. By 24 hr, there was no difference in cumulative dose among groups. Postoperative pain scores and the incidence of respiratory events, nausea, vomiting and pruritus were comparable among groups. These data suggest that intrathecal morphine at 30 micrograms.kg-1 provides the most intense analgesia at 6 hr following selective dorsal root rhizotomy, but was otherwise comparable to the 10 micrograms.kg-1 dose.

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Chiari malformations comprise four different hindbrain anomalies originally described by Hans Chiari, a professor of pathology at the German University in Prague. There are four basic Chiari malformations. The reasons for revision of Chiari malformation decompression may be for conservative or inadequate initial decompression or the development of postoperative complications. Another reason involves cases of both hindbrain herniation and syringomyelia in patients who have undergone adequate posterior fossa decompression without resolution of symptoms, signs, or radiological appearance of their syrinx cavity. Additionally, symptom recurrence has been reported in association with various types of dural grafts. Reoperation or revision surgery for patients with Chiari malformations is common and may not be due to technical error or inadequate decompression. The types of revision surgeries, their indications, and initial presentations will be reviewed.

The pressure-volume index (PVI) technique of bolus manipulation of cerebrospinal fluid (CSF) was used to measure changes of neural axis volume buffering-capacity and CSF dynamics produced by different conditions of the skull and dura. Twenty-eight cats were studied in the intact state, after bilateral craniectomy, and with the dura opened. At each stage of altering the container of the brain, the following parameters were obtained: steady-state intracranial pressure (ICP), sagittal sinus venous pressure, PVI, and the resistance to the absorption of CSF. The resistance to absorption of CSF was determined using both the bolus injection and the continuous infusion of fluid. After craniectomy, PVI increased from 0.76 +/- 0.04 to 1.3 +/- 0.07 ml (+/- standard error of the mean) (p less than 0.001) and increased further to 3.6 +/- 0.17 ml (p less than 0.001) after opening the dura. The resistance to absorption of CSF (Ro), determined by bolus injection, decreased after craniectomy from 91.3 +/- 7.5 to 56.3 +/- 6.2 mm Hg/ml/min (p less than 0.001) and decreased further to 8.9 +/- 0.66 mm Hg/ml/min (p less than 0.001) after opening the dura. Although resistance determined by constant infusion was similar, results were dependent on the rate of infusion. Despite these changes of resistance and PVI, steady-state ICP and sagittal sinus venous pressure were similar in all three conditions of the skull and dura. These studies indicate that changes of the container of the brain affect pressure-volume relationships within the neural axis. However, the changes of resistance to absorption of CSF are in a direction that preserves a steady-state hydrodynamic equilibrium.