Acute deterioration in Chiari type 1 malformation after chiropractic cervical manipulation

Type 1 Chiari malformation consists of caudal displacement of the cerebellar tonsils through the foramen magnum. It may also be associated with displacement of the medulla and hydromyelia or syringomyelia. The natural history is variable, with most patients presenting between the 3rd to 5th decades.1 In a reported series of 71 patients, 69% presented with pain, 56% had weakness, 52% had numbness, and 40% complained of unsteadiness.2Mohr et al 1 classified patients' presentations into four main groups: syringomyelia, paraparesis, cerebellar, and “raised pressure'. We describe a patient with a previously relatively asymptomatic complex chiari 1malformation who acutely deteriorated after chiropractic manipulation of the cervical spine. This white woman first presented at the age of 47 years in August 1995. She had sustained a mild “whiplash” injury in April 1995, having been struck at low speed from behind while sitting in a stationary car. She developed neck pain a few days later and this became progressively more annoying over the next 2 months. She then attended for chiropractic manipulation of the neck. This included repetitive high velocity, low amplitude thrusting movements at