Chiari I Malformation

A Chiari I Malformation is a condition where part of the brain called the cerebellar tonsils extends down into the spinal canal, which is part of the central nervous system. This abnormal positioning can block the flow of cerebrospinal fluid and cause pressure on the brainstem and spinal cord. People with this condition may experience symptoms like headaches, especially after coughing or straining, as well as problems with balance and coordination. The malformation affects how the brain and spinal cord function together, potentially leading to neurological symptoms. It is often diagnosed in adolescence or adulthood but can be present from birth.

Chiari I Malformation is a congenital or acquired structural defect characterized by the downward herniation of the cerebellar tonsils at least 5 mm below the foramen magnum into the cervical spinal canal. This displacement disrupts normal cerebrospinal fluid (CSF) flow and can cause brainstem compression and neurological dysfunction. The condition is often idiopathic but may be associated with congenital anomalies such as spina bifida or acquired causes like CSF hypovolemia. Clinically, it presents with symptoms including occipital headaches, cerebellar signs, and sometimes syringomyelia due to altered CSF dynamics. The malformation is significant because it can lead to progressive neurological deficits if untreated.