Chiari 1 Malformation Resources

Types of Chiari Malformations

1. Type 1 occurs during fetal development and is characterized by downward displacement by more than four millimeters, of the cerebellar tonsils beneath the foramen magnum into the cervical spinal canal.
2. Type 2 characterized by downward displacement of the medulla, fourth ventricle, and cerebellum into the cervical spinal canal, as well as elongation of the pons and fourth ventricle. This type occurs almost exclusively in patients with myelomeningocele.
3. Type 3 is a form of dysraphism with a portion of the cerebellum and/or brainstem pushing out through a defect in the back of the head or neck. These malformations are very rare and are associated with a high early mortality rate, or severe neurological deficits in patients that survive
4. Type 4 the most severe form and the rarest. The cerebellum fails to develop normally. There may be other associated malformations of the brain and brainstem. Most babies born with this malformation do not survive infancy.

Chairi 1 Malformation Symptoms

• Severe head and neck pain
• An occipital headache felt at the base of the skull that is made worse by coughing, sneezing, or straining
• Loss of pain and temperature sensation of the upper torso and arms (as a result of a syrinx)
• Loss of muscle strength in the hands and arms (as a result of a syrinx)
• Drop attacks – collapsing to the ground due to muscle weakness
• Spasticity
• Dizziness
• Balance problems
• Double or blurred vision
• Hypersensitivity to bright lights
• Brain stem findings, e.g. swallowing or breathing difficulties 

Decision to operate based on symptomatology

• Head-aches, classically sub-occipital, worsened by a Valsalva maneuver
• Brain stem symptoms, e.g. respiratory distress, central sleep apnea, diminished fine motor skills
• Truncal symptoms, e.g. progressive scoliosis
• Distal neurological symptoms, e.g. ataxia, bowel/bladder incontinence

Decision to operate based on MRI

• Enlarging Syrinx
• Signal changes within the cord/brain stem
• Reduced flow on cine studies
• Progressive tonsillar herniation

Chairi 1 Malformation Recovery

Greater than 90% of syrinxes will reduce in size after decompression and 50-90% of patients will have improvement in their pre-operative symptoms.

Why is the procedure more difficult at a younger age?

• Size – more difficult to get adequate bony decompression
• Bony healing – greater tendency to close openings1
• Greater growth – more changes in skull morphology
• Associated symptoms – higher incidence of respiratory and lower cranial nerve dysfunction