- What Is It?
- Life Expectancy
What Is Chiari Malformation?
Chiari malformations refer to a group of congenital abnormalities of the brain that affect the structural relationships between the cerebellum, brainstem, the upper cervical cord (craniocervical junction), and the bony cranial base.
There are four main types of Chiari malformations:
- Chiari type I malformation is the most common, the least severe, and is usually diagnosed in adults.
- Chiari type II malformation is less common, more severe, almost invariably associated with a type of spina bifida (myelomeningocele), and patients usually become symptomatic in infancy or early childhood.
- Chiari type III and IV malformations are extremely rare and generally fatal.
What Are Symptoms of Chiari Malformation?
Chiari type I malformation is usually diagnosed in adulthood and symptoms include:
- Headache, especially after coughing, sneezing or straining
- Neck pain
- Spinal cord injury (myelopathy)
- Cerebellar symptoms such as involuntary eye movements, disruptions in speech patterns, loss of muscle control (especially in the trunk)
- Lower brainstem symptoms such as problems speaking, problems swallowing, involuntary eye movements (especially looking down), hoarseness, palate weakness, tongue atrophy, recurrent aspiration, and sleep-related breathing disorders such as sleep apnea
- Central spinal cord symptoms such as hand weakness, dissociated sensory loss, and loss of sensation that spreads over the shoulders and back (cape anesthesia)
Chiari II malformation is usually diagnosed with infants and younger children and symptoms include:
- Swallowing/feeding difficulties
- Cessation of breathing (apnea)
- A weak cry
- Involuntary eye movements
- Weakness of extremities
Despite extensive malformations, some patients with Chiari II have normal intelligence and can function independently.
Chiari type III has a high mortality rate. Those who survive beyond the neonatal period may have symptoms including:
- Severe neurologic impairments
- Mental retardation
- Low muscle tone or muscle spasm
- Upper and lower motor neuron signs
- Lower cranial nerve palsies
Chiari type IV malformations are generally incompatible with life and data are limited regarding symptoms as patients do not survive.
What Causes Chiari Malformation?
The main cause of Chiari malformations is a result of structural deficiencies in the brain and spinal cord that take place during development of the fetus. This can be due to:
When Chiari malformations occur later in life, they may be due to excessive draining of spinal fluid from the lumbar or thoracic areas of the spine either due to traumatic injury, infection, or disease.
How Is Chiari Malformation Diagnosed?
Other tests that may be performed include:
- CT scans of the neck and head
- X-rays of the neck and head
What Is the Treatment for Chiari Malformation?
Patients with Chiari I malformations who have mild symptoms may only need conservative treatment for mild headaches and neck pain, such as:
- Pain relievers (analgesics)
- Muscle relaxants
- Use of a soft collar
Surgical treatment may be required for more pressing symptoms, and early surgical intervention is often associated with better outcomes. Types of surgery include:
- Suboccipital craniectomy
- Cervical laminectomy
- Arachnoid dissection
What Are Complications of Chiari Malformation?
Complications of Chiari type I malformation patients include an increased risk of concussion and post-concussion syndrome.
In other patients, Chiari malformation can be progressive and lead to other complications, such as:
- Spina bifida (incomplete closing of the spine and spinal cord covering)
- Syringomyelia (a cyst or cavity forms in the spinal cord)
- Hydrocephalus (buildup of excess fluid within the brain)
- Tethered cord syndrome (tissues attach to the spinal cord, causing limited movement of the spinal cord within the spinal column)
What Is the Life Expectancy for Chiari Malformation?
Life expectancy for Chiari malformation depends on the type.
Patients with Chiari type I malformation, the mildest form of the condition, are typically diagnosed in adulthood and have a normal life expectancy and good outcomes with treatment and/or surgery.
Despite extensive malformations, some patients with Chiari II have normal intelligence and can function independently. The outlook depends on the specific malformations present in each individual.
Chiari type III malformation patients have a very high mortality rate, and patients often die in infancy due to respiratory failure. Chiari type IV malformations are incompatible with life.
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