Atlantooccipital Assimilation and Basilar Invagination Treated Successfully in a Young Male With Marfanoid Features: A Stitch in Time.

Marfan syndrome is a spectrum of disorders caused by a genetic defect involving connective tissue and is heritable by the autosomal dominant mode of inheritance. Atlantooccipital assimilation is a partial or complete fusion of the atlas and the occiput base congenitally. Although primarily asymptomatic, some patients with atlantooccipital assimilation may present with neurological issues, including myelopathy. Here, we are discussing a case of an 18-year-old male who presented with bilateral paraesthesia, tingling and neck pain which, upon investigations, turned out to be a case of atlantooccipital assimilation along with basilar invagination with spinal cord compression. The patient also had marfanoid features like tall stature, reduced upper to lower segment ratio, and increased arm span to height with positive wrist and thumb signs. As myelopathy had already developed, the patient was treated surgically rather than with medical management with a favorable outcome.