Hindbrain-hernia-related syringomyelia without syringobulbia, complicated by permanent nocturnal central hypoventilation requiring non-invasive ventilation.

INTRODUCTION

In the absence of syringobulbia, hindbrain hernia does not commonly cause permanent respiratory complications. We present two patients who developed permanent central nocturnal hypoventilation following acute deterioration of hindbrain-hernia-related syringomyelia despite successful surgery.

PATIENTS: Two children (one boy and one girl, aged 7 and 13 years, respectively) presented with acute neurological deterioration. The boy presented with a 6-week history of progressive tiredness and weakness and a short history of respiratory depression. The girl presented with a 2-year history of left hemiparesis and a short history of left hemiplegia and respiratory depression. On magnetic resonance scan, both had hindbrain hernia, hydrocephalus and cervical syringomyelia. Following cranio-vertebral decompression and, later, a ventriculoperitoneal shunt, the syringomyelia remained well controlled in both patients. In contrast, their respiratory depression improved minimally. Repeated multichannel respiratory monitoring revealed a persistently slow sleeping respiratory rate, with nocturnal hypercapnia and hypoxemia, managed successfully by night-time non-invasive ventilation. Neither the boy nor the girl, after 7 and 4 years, respectively, has developed any complications of nocturnal hypoventilation. When awake, both breathe normally.

RESULT: Both children appear to have suffered a permanent impairment of respiratory control, resulting in nocturnal hypoventilation. This is usually seen with brain stem lesions and is unexpected when syringomyelia does not extend above C2, in the absence of syringobulbia.

DISCUSSION: Central nocturnal hypoventilation is postulated to be due to permanent damage of central brain stem pathways controlling the respiratory muscles, due to local pressure at the cranio-cervical junction associated with acute deterioration of the hindbrain herniation.

CONCLUSION

Sudden deterioration of hindbrain hernia and cervical syringomyelia can rarely impair the central mechanisms of respiratory control, with long-term implications on quality of life.