Acquired heterotopic ossification following encephalitis and intractable seizures.

Case History The subject is a 26-year-old female with no past medical history, who was admitted for seizures and concurrent febrile illness. A magnetic resonance imaging (MRI) of the brain was unremarkable, and cerebrospinal fluid cultures were negative. She was treated for presumed viral encephalitis, which was complicated by status epilepticus. She was placed under phenobarbitone-induced coma followed by thiopentone-induced coma and required intubation for 28 days. She was subsequently treated with a combination of oral lamotrigine, phenytoin and valproate and developed cholestatic hepatitis secondary to the antiepileptic medication. When the patient was transferred out to the general ward, she continued having several seizures a day. There were apparent cognitive deficits, namely disorientation, short attention span, short-term memory loss, inappropriateness and deficiency in executive functioning. Six weeks after admission, she complained of acute thigh pain. It was noted that there was difficulty in performing range of motion therapy 3 days before this complaint. X-ray of the pelvis and lower limbs did not reveal any fracture but there was vague haziness in the soft tissues. A computed tomographic (CT) scan of the lower extremities was then performed, which revealed ossification mainly in the adductor muscles as well as the vastus medialis bilaterally (Fig. 1). The diagnosis of HO was also confirmed with a triphasic bone scan. She was transferred to Rehabilitation Medicine, and was treated with diclofenac and etidronate for 6 and 12 weeks respectively. Gentle range-of-motion exercises were started albeit with difficulty due to severe pain, and there was difficulty getting the patient into a functional position due to her hips being in a position of external rotation. With further therapy, pain was reduced with improved range of motion. She was eventually able to ambulate with elbow crutches with the hips abducted, externally rotated, and slightly Acquired Heterotopic Ossification following Encephalitis and Intractable Seizures