Arnold-Chiari Malformation

A Chiari Malformation consists of a displacement of the cerebellar tonsils through the foramen magnum and sometimes causes hydrocephalus as a result of obstruction of cerebrospinal fluid drainage. It can cause headaches, fatigue, muscle weakness in the head and face, difficulty swallowing, dizziness, nausea, impaired coordination, and, in severe cases, paralysis. Incidence ranges between 1:1000 and 1:5000.
There are 4 types of increasing severity with Type III and IV being exceedingly rare.

Type I (most common): Headaches, fatigue, muscle in the head and face, difficulty swallowing, dizziness, nausea, impaired coordination, and, in severe cases, paralysis. Usually adult onset, is treatable, not curable and rarely fatal.
There is a hereditary version which is related to connective tissue dysfunction. Patients with hypermobility or connective tissue deficiency such as Ehlers Danlos and Marfan syndrom may develop a Chiari malformation.

Type II: Type I plus a myelomeningocele which causes paralysis below the spinal defect; 15% of patients die within 2 years of birth.

Type III: Severe neurodevelopmental defects in addition to above symptoms

Type IV: Lack of cerebellar development; Type III and IV patients typically do not live beyond 2-3 years of life.

What we'll see in the chair:
-mild to moderate mental retardation
-dysphagia
-facial pain
-nystagmus
-vertigo
-tachycardia
-headaches secondary to Valsalva maneuvers

Treatment:
Decompression surgery to relieve the buildup of CSF is the most common treatment. Shunts and removal of occipital bone have also been used. There has also been success with transnasal endoscopic surgery.

Summary:
While it is most often adult onset, with a relatively high incidence we will almost certainly see this in our chair at some point. With my minimal exposure, I would compare the behavior and mental status to a patient with Aspergers and/or ADHD. The nystagmus for both of my patients was also very salient.