LAUSR

Dear Editor: In response to your September 2019 issue that highlighted decompressive craniectomy, we will present an unusual case of “complex Chiari malformation” complicated with necrotizing encephalopathy caused by a novel influenza A (H1N1) virus. A 3-year-old previously asymptomatic girl, presumably immunocompetent, was admitted to a local hospital with 1 day of fever and mild digestive symptoms where she had a tonicclonic seizure and urinary incontinence during her stay in the emergency department. The next day, after receiving antiepileptic medication, she was transferred to another hospital. Initially, empiric broad-spectrum antibiotic therapy was initiated and later oseltamivir treatment was added because of her positive oropharyngeal PCR testing for H1N1 viral infection. On day 6 of the illness, she had hematemesis and hypoventilation and was intubated. Her pupils became dilated and nonresponsive to light on the next morning. High-dose anti-edema treatment was started because of the presence of severe cerebral edema involving the brainstem and cerebellum on theMRI scan (Fig. 1 b and c). Surprisingly, there was also a marked tonsillar ectopia and basilar invagination with retroflexion of the odontoid (Fig. 1a). With this history, she was then transferred to our hospital on day 8 of the onset of her symptoms. Her GCS score was 2T with bilateral fixed and dilated pupils and unstable vital signs. She was urgently taken to the operation room and a posterior fossa decompression with a C1 laminectomy and tonsillectomywas performed as a salvage procedure. During the surgery, swelling of the brain parenchymal tissue was observed due to the very high ICP. After the surgery, her neurologic examination had no improvement and her vital signs remained unstable. The patient’s condition continued to deteriorate and she died on day 10 of the illness. It was reported that surgical specimen sent during surgery was PCR negative for the H1N1 virus. Currently, H1N1 is a well-documented infectious disease causing a wide range of neurologic dysfunction that includes acute necrotizing encephalopathy which is one of the most devastating forms of H1N1 infection and is a rare but serious complication of the disease. Radiologically, MRI findings demonstrated bilateral thalamic involvement, in addition to extensive involvement of the brain stem and cerebellum, despite an absence of viral footprints in the central nervous system as previously documented in the literature, as we observed [7]. Autoimmune and cytokine-related pathways are suggested to lead to the development of encephalopathy [2]. Despite antiviral and anti-edema treatment, neurological worsening is usually caused by increased ICP and the poor outcome is related to herniation due to malignant edema which is unavoidable in such cases [1, 4]. Therefore, an urgent decompressive craniotomy or craniectomy should be considered in the management of these cases that are complicated by the presence of cerebellar tonsil herniation with or without basilar invagination [1, 3, 5, 6]. To the best of our knowledge, this is the first report of suboccipital decompressive craniectomy for “complex Chiari malformation” associated with necrotizing encephalopathy caused by H1N1 viral infection in literature. It is possible that the presence of basilar invagination and the small posterior fossa volume accelerated the devastating course of the disease in our patient by decreasing the tolerance for extensive cerebral edema caused by the H1N1 infection. In our opinion, multiple transportations of the patient might also have caused * Mehmet Turgut [email protected]