HeadWise HeadWise: Volume 3, Issue 2 | Page 20

DEFINITION Chiari malformations are a group of developmental abnormalities that are located in the back of the brain. These malformation occur when the posterior or back region of the skull which contains the cerebellum is either too small or deformed, thus putting pressure on and crowding these nervous system structures. The lowermost portion of the cerebellum, known as the cerebellar tonsils, become displaced downwards into the upper spinal canal, and thus interferes with the normal flow of the cerebrospinal fluid (CSF) which circulates around the brain. These actions may lead to increased pressure inside the cranium and can also cause pressure on the upper spinal cord. C hiari malformations are classified into four different types depending on the part of the brain tissue that is displaced into the spinal canal and whether other developmental abnormalities are present. This article will focus on Chiari malformation type I—the most common type of these malformations. 2. CHIARI MALFORMATION TYPE I Chiari Malformation Type I is usually diagnosed during adolescence or in adulthood. In this type of malformation, the cerebellar tonsils become displaced below the foramen magnum. The foramen magnum (from the Latin: “great hole”) is a large opening in the occipital bone of the cranium. It is one of the several openings (the foramina), through which the medulla oblongata enters and exits the skull vault. Chiari malformation Type I is usually asymptomatic. 3. 4. 5. 6. SYMPTOMS usually, Chiari Type I Malformation is an incidental finding; however, depending on the severity and extent of the abnormality, it can appear with different clinical symptoms. The onset of symptoms is usually in the second or third decades of life. 1. Headaches: Headaches are the most common symptom associated with Chiari type I malformation. These headaches often worsen with 18 HEAD WISE | Volume 3, Issue 2 • 2013 7. 8. 9. 10. 11. 12. coughing, sneezing, or straining. Patients may also complain of headaches at the base of the skull which can worsen with exertion. Neck pain: Individuals with Chiari Malformation Type 1 may also experience neck pain and stiffness. Pain radiating to the shoulders may be present. unsteadiness: These patients may complain of an unsteady gait and a feeling they are off-balance. Difficulty with dexterity: Some patients may experience impaired fine motor skills such as trouble writing or using utensils. Numbness and tingling of hands and feet: Tingling of the hands is more common. Visual problems: Pain behind the orbit of the eye, and visual difficulties such as floaters, blurred vision, double vision, peripheral visual loss, and downbeat nystagmus (downward jerky movements of the eyes) may be reported. Dizziness or vertigo. Trouble swallowing. Fluctuating hearing loss Shooting facial or throat pain Drop attacks: Rarely, patients will complain of unexplained falls due to leg buckling. Syncope: Fainting associated with sneezing or coughing is unusual.