Cerebellar tonsillar descent: A diagnostic dilemma between Chiari malformation type 1 and spinal cerebrospinal fluid leak.

Cerebellar tonsillar descent can be seen on head magnetic resonance imaging in both Chiari malformation type 1 and spinal cerebrospinal fluid leak creating the potential for misdiagnosis. We report five cases of spinal cerebrospinal fluid leak at Stanford University initially misdiagnosed and treated as Chiari malformation type 1 based on cerebellar tonsillar descent demonstrated on imaging. All five cases had sustained relief at the 6-month follow up visit from epidural blood patches for the treatment of spinal cerebrospinal leak after unsuccessful suboccipital decompression surgeries. A misdiagnosis of Chiari malformation type 1 in patients with spinal cerebrospinal fluid leak may lead to unnecessary surgeries instead of the less invasive treatment, such as epidural blood patches. It is imperative to consider a spinal cerebrospinal fluid leak in the differential based on clinical-radiological correlation and not solely on cerebellar tonsillar descent demonstrated on imaging.