Chiari 1.5 malformation: a case report and review of literature

Chiari 1.5 malformation, a rare neurological disorder, involves cerebellar tonsil herniation and slight brainstem descent through the foramen magnum. A 25-year-old woman presented with recurrent headaches exacerbated by coughing, straining, and difficulty in maintaining head posture despite normal motor functions and reflexes. MRI revealed a Chiari 1.5 malformation with a 13.5 mm cerebellar tonsil herniation, minor brainstem descent, and C2-C3 vertebrae fusion. Suboccipital craniectomy with foramen magnum decompression significantly alleviated her symptoms. This case emphasizes the importance of recognizing Chiari 1.5 malformation as a cause of headaches in young adults and supports surgical intervention to prevent neurological decline. Although the aetiology is unknown, theories suggest a pressure differential between the cranial and spinal subarachnoid spaces during fetal development. Early diagnosis and posterior fossa decompression are crucial for symptom management and outcome improvement in CHIARI 1.5.