Intrapleural Migration of Ventriculoperitoneal Shunt due to Negative Intrathoracic Pressure.

Ventriculoperitoneal (VP) shunt is still a mainstay of treatment in centers for infants with aqueductal stenosis which is the most common cause of congenital obstructive hydrocephalus. Shunt migration remains a common complication. Delayed distal shunt tip migration into the thoracic cavity due to negative intrathoracic pressure is a rare occurrence.  Authors report a 1-year-old infant presenting with drowsy sensorium, increasing head circumference, and bulging anterior fontanelle. Magnetic resonance imaging of the brain revealed significant obstructive hydrocephalus with periventricular seepage. A large expansile diverticulum of the suprapineal recess extending infratentorially compressing the dorsal midbrain and cerebellum inferiorly. The child underwent an emergency right-side VP shunt (medium pressure) in view of clinical symptoms of raised intracranial pressure. A right iliac fossa infraumbilical transverse incision was taken for placing the abdominal end. Visual confirmation of bowel was done after opening the peritoneum by two operating surgeons prior to inserting the distal catheter. Postoperative course was uneventful. The child presented 3 months later with acute dyspnea and diminished breath sounds on the right hemithorax. Neurologically, the child was active, feeding well, and anterior fontanelle was lax. A chest roentgenogram and computed tomogram (CT) of the thorax revealed complete shunt migration into the pleural space with significant pleural effusion on the right side. The distal shunt system on CT appeared to enter the pleural space below the 8th rib, probably indicating that there was subcostal tunneling of the shunt below the 8th rib space during the first surgery which was inconspicuous and subsequently over a span of 3 months due to sucking effect of negative intrathoracic pressure the shunt gradually migrated into the pleural cavity which led to the effusion. An emergency VP shunt revision was performed. The distal end below the chamber was retunneled subcutaneously into a new incision in the left paraumbilical region. Postoperative chest and abdomen roentgenograms showed resolving effusion and accurate shunt placement. The child required elective ventilation temporarily to tide over the underlying lung collapse and an intercostal tube drainage for the cerebrospinal fluid (CSF) hydrothorax for 2 days to aid in quicker weaning. The child was discharged on the 5th postoperative day.  Intrapleural migration of VP shunts has been contemplated to be due to trauma during surgery, migration across foramen of Bochdalek or Morgagni, and negative intrathoracic pressure. Taub and Lavyne have classified thoracic complications of VP shunt as thoracic trauma during shunt tunneling, supradiaphragmatic migration of shunt or transdiaphragmatic migration of shunt, and pleural effusion complicated by CSF ascites. Transdiaphragmatic migration is commonly seen in pediatric population and supradiaphragmatic migration can be seen in any age group. We believe our case to be a type of supradiaphragmatic migration of the shunt which has occurred slowly over a span of time due to the negative intrathoracic pressure. The idea behind this clinical case image is to edify neurosurgeons, pediatricians, and intensivists to remain wary of such a complication.