Hindbrain-related syringomyelia and raised intra-abdominal pressure: Implications for safety of laparoscopic and robotic surgery

BACKGROUND: The causative role played by intra-abdominal pressure (IAP) in the syringogenesis of the Chiari 1 malformation syringomyelia has been still not adequately studied. The aim of this study is to validate the transmedullary theory about the hindbrain-related syrinx, also discussing the implications for safety of these patients related to the use of high-pressure CO2 pneumoperitoneum during laparoscopic and robotic surgery. METHODS: Fourteen patients with a hindbrain-related syrinx were candidate for a posterior fossa decompression. Preoperative and follow-up protocol involved conventional T1/T2 and cardiac-gated Cine phase-contrast MRI sequences. Peak systolic and diastolic velocities were acquired at four Regions Of Interests (ROI), namely syrinx, ventral and dor-sal cervical subarachnoid space, and foramen magnum region. Data were reported as mean ± SD. Patients were fol-lowed for three years. One-way ANOVA with Bonferroni post hoc test of multiple comparisons were performed, where p-value was <0.001. RESULTS: A systolic-diastolic pulsatile pattern of CSF was found in all cases inside the syrinx. Syrinx and premedullary cistern velocities decreased within the first month after surgery (<0.001). All symptoms apart from atrophy and spastic-ity improved. These data lead to validate the Oldfield and Heiss transmedullary theory about syringogenesis, within which an increased IAP play a key role. CONCLUSION: Raised IAP plays a paramount role in the formation and maintenance of the hindbrain-related syrinx. High-pressure CO2 surgical pneumoperitoneum is strongly discouraged in these patients because at risk of rapid neurological worsening. A low-pressure insufflation technique has a rationale in those patients having smaller or incidental syrinxes.