An overweight 15-year-old girl developed severe headache and visual loss with papilledema. A cranial magnetic resonance imaging (MRI) scan, MR angiogram, and MR venogram were negative. Serial lumbar punctures revealed elevated opening pressures consistent with idiopathic intracranial hypertension, i.e. pseudotumor cerebri []. Refractory to medical treatment, she underwent placement of a Medtronic Spetzler LP shunt. The Spetzler shunt has slit valves at its distal end and a catheter of small diameter, which provide resistance to CSF flow in order to regulate pressure. The patient did well with resolution of symptoms for 10 years. At age 25, she developed a 3-week history of severe headache and intractable nausea and vomiting. Vision remained intact as did her motor exam. However, decreased touch and pinprick sensation were noted in the left upper extremity. Repeat MRI of the head and cervical spine demonstrated an acquired Chiari I malformation with cerebellar tonsillar ectopia extending 16 mm below the foramen magnum, and a cervical syrinx from C2 extending to the T8 level []. Neither the Chiari I malformation nor the cervical syrinx were present on previous scans. We assumed that the new findings were the result of cranial spinal CSF pressure differentials caused by the lumbar drain. Weight reduction can result in resolution of pseudotumor cerebri. Because the patient had not undergone substantial weight loss and was not experiencing papilledema, it was assumed that the pseudotumor cerebri continued to be managed by her lumbar drain and that the drain was still working. The patient underwent placement of a right frontal programmable ventricular peritoneal shunt utilizing stereotactic navigation and ligation of the LP shunt. Postoperatively, she continued to have severe headaches, nausea, and vomiting. Follow-up computed tomography (CT) showed decreased ventricular size and persistent Chiari malformation. Secondary to persistent symptoms, a suboccipital craniectomy, C1 laminectomy, and duraplasty were performed 5 days after shunting. Bipolar cautery was used to shrink the tonsils and clear egress of CSF from the fourth ventricle was noted prior to closure. With shrinkage of the ventricles, there appeared to be excessive ventricular tubing, so the proximal catheter was repositioned. The patient's symptoms gradually resolved over time, including the sensory symptoms in her left arm. A follow-up MRI done 6 months postoperatively revealed a complete resolution of both the Chiari malformation and the syrinx [].