Chiari malformation



A Chiari malformation (CM) is a structural defect of the base of the skull and the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull). This can sometimes lead to non-communicating hydrocephalus as a result of obstruction of cerebrospinal fluid (CSF) outflow.

The cerebrospinal fluid outflow is caused by phase difference in outflow and influx of blood in the vasculature of the brain.

Chiari malformation is usually congenital but can happen later in life – called secondary Chiari malformation – in the case of spinal fluid leak due to traumatic injury, disease, or infection.

Symptoms
There are three types of Chiari malformation with many symptoms, some that overlap and others that are unique to that type. The three types are diagnosed at different stages of life such as an ultrasound given during pregnancy, during an exam at birth or infancy, or in older children and adults.

Chiari malformation can cause headaches, difficulty swallowing (sometimes accompanied by gagging), choking and vomiting, dizziness, nausea, neck pain, unsteady gait (problems with balance), poor hand coordination (fine motor skills), numbness and tingling of the hands and feet, and speech problems (such as hoarseness).

Less often, people with Chiari malformation may experience ringing or buzzing in the ears (tinnitus), weakness, slow heart rhythm, or fast heart rhythm, curvature of the spine (scoliosis) related to spinal cord impairment, abnormal breathing, such as central sleep apnea, characterized by periods of breathing cessation during sleep, and, in severe cases, paralysis.

Fibromyalgia
In the 1990s, there was controversy surrounding whether patients with Chiari malformation had been misdiagnosed with fibromyalgia or whether Chiari malformation could indeed cause the symptoms of fibromyalgia. A 2004 study of 270 patients with fibromyalgia diagnoses found that 46% had cervical spinal stenosis and 20% chiari malformation. However, a 2011 paper failed to find any increased rate of Chiari malformation among people with fibromyalgia. Chiari malformation is associated with Ehlers-Danlos syndrome , which is sometimes misdiagnosed as fibromyalgia, or with which there may be diagnostic overlap.