Complete intracranial migration of a ventriculoperitoneal shunt: Rare complication of a common procedure

Rakesh Kumar Sharma, Mayank Bansal, Manish Agrawal, Ashok Gupta, Virendra deo Sinha 
 Department of Neurosurgery, Sawai Man Singh Medical College, Jaipur, Rajasthan, India

Correspondence Address:
Manish Agrawal
Department of Neurosurgery, Sawai Man Singh Medical College, Jaipur, Rajasthan
India

Full Text

Sir,

Clinicians managing patients undergoing a ventriculoperitoneal shunt procedure must be aware of its possible complications and their early recognition. Here, we report a rare case of complete intracranial migration of a ventriculoperitoneal shunt, a potentially fatal complication. A 6-month-old female child presented with gradual enlargement of head and decreased oral intake. The child had a previous history of low birth weight and an occipital encephalocele (she was operated for the later condition). The patient developed hydrocephalus in the post-operative period for which a medium-pressure ventriculoperitoneal "Chabbra shunt" was inserted. After 3 months, the patient presented in an altered sensorium with decreased oral intake. The upper and lower ends of the shunt were re-explored, found to be functioning well, and left, in situ. On examination, the head was disproportionately enlarged with a bulging and tense anterior fontanel, engorged scalp veins, and the sunset sign. There was a small pulsatile swelling at the parietal burr hole site. The abdominal scar was puckered. The shunt catheter was not palpable anywhere across the chest wall. A guarded lumbar puncture revealed a normal cerebrospinal fluid (CSF) picture. The shunt catheter was not visible on a plain chest and abdominal radiographs. X-ray skull [Figure 1] and computed tomography (CT) of the head [Figure 2] showed the entire shunt catheter lying inside the cranium, confirming the upward migration. The CT head also showed gross hydrocephalus, with a thin cortical mantle. Endoscopy-assisted removal of the migrated shunt with placement of a new shunt on the opposite side was planned. Under general anesthesia, a zero degree, rigid endoscope was introduced through the Kocher's point inside the ventricle where the coiled and migrated shunt was seen. The tip of the shunt was found adherent to the choroid plexus. Attempts at separation of the adherent shunt resulted in mild intraventricular bleeding. In spite of constant saline irrigation and bipolar coagulation, the bleeding did not stop. Finally, the procedure was abandoned. An external ventricular drain (EVD) was placed inside the ventricular cavity. In the post-operative period, the child continued to be dull but the anterior fontanel remained lax. There was blood-tinged CSF emerging from the EVD. In spite of our best efforts, the child expired after 24 hours.{Figure 1}{Figure 2}

The ventriculoperitoneal shunt procedure is a deceptively simple operation with a wide range of complications. Mechanical shunt failure is the most common complication. Complete intracranial migration of the ventriculo-peritoneal shunt is extremely rare [1] with a reported incidence of 0.1-0.4% of all shunt procedures. [2],[3] On reviewing the database in PubMed and Google Scholar, we found only nine reported cases of total intracranial shunt migration. The factors that may be responsible for the migration of the shunt are malnourishment (less subcutaneous tissue for anchorage), anemia, sepsis, and a thin cortical mantle. [4] Excessive neck movements producing a windlass effect coupled with a large potential subgaleal space created for chamber positioning, dilated ventricles with negative suctioning pressure, or a positive intra-abdominal pressure may be responsible for the migration. [5] The technical factors include a large burr hole, larger dural opening, re-exploration leading to poor local tissue availability for anchorage, and an improper shunt securing. [6] The "Chabbra" shunt, having a cylindrical chamber can easily pass into the cranium. [7]

Shunt migration may be prevented by taking precautions during the procedure, especially in high-risk patients. If the shunt has recently migrated proximally and is not considered adherent to the choroid plexus, the decision to remove it may be taken. In case of any suspicion of adherence of the shunt tubing to the choroid plexus or the ventricular ependyma, the shunt should be left in situ. Optimum creation of the subgaleal space for the shunt chamber, a smaller burr hole, a smaller dural opening, and proper anchorage of the chamber to the pericranium, are some of the measures that may be useful in obviating this complication. [8]

References