Patient presents with signs and symptoms suggestive of ventriculoperitoneal shunt malfunction.  Presenting complaints include headache, nausea, vomiting, lethargy, irritability, and altered mental status.  These symptoms may indicate increased intracranial pressure.  On physical examination, findings may include papilledema, altered level of consciousness, focal neurological deficits, or signs of meningeal irritation.  The patient's medical history is significant for hydrocephalus requiring VP shunt placement.  Differential diagnosis includes infection, shunt obstruction, overdrainage, and subdural hematoma or hygroma.  Initial diagnostic workup may include head CT scan, shunt series x-rays, and possibly MRI brain.  Treatment plan may involve shunt revision or replacement surgery, depending on the cause of the malfunction.  Neurological consultation may be warranted.  Patient education regarding VP shunt complications and follow-up care will be provided.  This documentation supports the diagnosis of VP shunt malfunction with ICD-10 code T85.898A (Other mechanical complication of other specified internal prosthetic devices, implants and grafts, initial encounter).  CPT codes for potential procedures include 62160 (Ventriculoperitoneal shunt revision) or 62223 (Creation of shunt, ventriculoatrial, ventriculoperitoneal, or ventriculopleural).  Medical necessity for procedures will be documented and justified based on clinical findings and imaging results.