Chiari Malformation

What is it?

A Chiari malformation, previously called Arnold Chiari malformation, is where the lower part of brain protrudes into the spinal canal. There are four main types of Chiari but type 1 Chiari is the most common. Here the lower part of the back of the brain extends into the spinal canal. This puts pressure on the brain stem, spinal cord and obstructs the flow of fluid (CSF).

What are the causes?

• The exact cause is not known. It tends to be present from birth, but normally found in adult hood when symptoms manifest or when an MRI is done.
• Skull may not be big enough for the brain
• It can also develop in people with tethered cord, hydrocephalus an din some types of brain tumor
• It can run in families due to faulty genes

What are the symptoms?

• Headaches usually felt in the back of the head, worsened by straining, coughing and sneezing.
• Neck pain
• Dizziness and balance problems
• Muscle weakness
• Tingling and numbness in arms and legs
• Double vision, blurred vision and sensitivity to light
• Swallowing problems
• Hearing loss and tinnitus

Diagnosis:

• Proper clinical history and a detailed neurological examination.
• MRI to see for the severity of the lesion and any other associated pathology
• Complications associated with Chiari malformation:
• Hydrocephalus: accumulation of excess fluid in the brain
• Spina bifida: where the spinal cord and it coverings are not fully developed
• Syringomyelia: where fluid accumulates in the spinal cord
• Tethered cord: where the spinal cord attaches to the spine and gets stretched. This may result in severe nerve and muscle damage in the lower body

Treatment:

Treatment depends on the severity of the symptoms. Asymptomatic chiari needs no treatment. If there is associated increased fluid in the brain (hydrocephalus) then CSF diversion called ventriculo peritoneal shunt is the best If there is no hydrocephalus, then the more common posterior fossa decompression is a better option. Here a small part of the bone in the back of the skull is removed to relieve the pressure in the brain. Along with it the coverings of the brain is opened and a patch is sewn to make it roomier.

Authored By Dr. Sai Sudarsan