Arnold Chiari Syndrome

What is Arnold Chiari Syndrome?

Malformation of the cerebellum, which is a major part of brain and assists to body balancing is clinically termed as Arnold Chiari Syndrome.

The anatomical malformation in Arnold Chiari Syndrome causes functional abnormality in the cerebellum. In normal human being, the cerebellum and a portion of the brain stem locate at the lower portion of the skull and just above the starting part of the vertebral column ( termed as foramen magnum). In Arnold Chiari Syndrome, cerebellum sited below the foramen magnum.

In Arnold Chiari Syndrome, bony space in the skull is smaller than the normal individual. Therefore, a congested setting of the cerebellum and brain stem pressed down and placed into the foramen magnum and into the upper vertebral column. The resulting of this causes pressure difference in the cerebellum and brain stem and also obstruct the cerebrospinal fluid flow1,2.

Arnold Chiari Syndrome


Depending on the severity of the symptoms and the portion of brain projected out from the vertebral column, Arnold Chiari Syndrome is further classified into four types.

Type 1

In this type of Arnold Chiari Syndrome, the lower part of the cerebellum extended into the foramen magnum, but brain stem positioning is not altered. This type of Arnold Chiari Syndrome is the most common type and it is asymptomatic (no symptoms arise). This type of Arnold Chiari Syndrome can appear due to acquired reason. This type of Arnold Chiari Syndrome is noticeable at the adulthood, may during examine another condition.

Arnold Chiari Syndrome Type 1

Type 2

Type 2 Arnold Chiari Syndrome is also known as classic Chiari Syndrome. In this condition both cerebellar and brain stem extended into the foramen magnum. In association with this partial or complete absence of nerve tissues, which connects both halves of the cerebellum.

This deformity is started at the fetus developmental phase because the spinal cord is opened at the time of birth and resultant of this leads to spina bifida. Therefore, affected children have a sac-like opening protrude through the backbone. Patients affected with Type 2 Arnold Chiari Syndrome causes in partial or complete paralysis of the region lower part of the spinal opening.

Arnold Chiari Syndrome Type 2

Type 3

Another common form type of Arnold Chiari Syndrome and provide most serious outcomes. In this condition, both the cerebellum and brain stem herniate or protrude through the foramen magnum and into the spinal cord. In addition, the fourth ventricle of the brain also protrudes through the spinal cord. This condition hampers CSF circulation. Type 3 provides severe neurological defects.

Arnold Chiari Syndrome Type 3&4

Type 4

In type 4, the cerebellum is underdeveloped and the condition also termed as cerebellar hypoplasia. This is a very rare type of Arnold-Chiari Syndrome. In this condition, a portion of the cerebellum is lost1,3.


The type 2 is specifically termed as Arnold-Chiari Syndrome. The name of the condition is derived from two pioneer researchers, who first demonstrated the condition.

The development of Arnold Chiari Syndrome is sporadic. There is no family history involve in the development of this condition, though detail knowledge is unknown. Genetic involvement may play a role in the development of the disease, but researchers also expect the environmental factors like lack of vitamins, minerals, and other nutrients also have a role in producing this condition.

The exact cause of the disease development is yet unclear and no certain data obtained, which clearly indicates about the estimation of the recurrence risk for family members. In 1971, when Arnold-Chiari first demonstrated this condition, they found two sisters had similar malformation associated with hydrocephalus and meningomyelocele. For detail information, further detail research work need to conduct1,4.


Following are the symptoms of Arnold-Chiari Syndrome:

  • Neck pain
  • Ataxia or body balancing problem
  • Weakness in the muscles
  • Numbness in both extremities
  • Dizziness
  • Buzzing sensation in the ear
  • Hearing problem
  • Loss of hearing
  • Vision problem
  • Swallowing difficulty
  • Vomiting
  • Insomnia
  • Headache
  • Depression
  • Irregular coordination of hands
  • Impaired fine motor skills

The above-mentioned symptoms are not seen in every case. Infants affected with Arnold Chiari Syndrome usually have to feed difficulty, irritable mood, arm weakness, weak cry, neck stiffness, breathing difficulty, vomiting. delayed development and the poor gaining of weight. Patients also have impaired reflex action and sensation and motor skills1,2,5.


Physical examination

During physical examination doctor usually noticed the above-mentioned symptoms, which is considered as an indication of the Arnold-Chiari Syndrome. Other diagnostic measures include:


Electromagnetic energy providing X-Ray can provide bone and tissue images, which reveals the head and neck abnormality.


Computed tomography (CT) scan also conducted to detail detection of the associated irregularities, like bony deformities, vascular irregularities, associated brain tumors and/or cysts formation, brain injury, and other disorders.


Magnetic resonance imaging (MRI) is another imaging tool applied to diagnose an Arnold-Chiari Syndrome. this is also noninvasive and painless process, which can provide detail structural description of the brain and spinal cord1,2,4.


If Arnold Chiari Syndrome is asymptomatic and does not interfere with the daily activity, then no treatment require treating the condition. But if the symptoms are progressive and hamper patient’s daily activity then surgical intervention is an only treatment option for Arnold-Chiari Syndrome. Usually, three surgical procedures are applied, which include:

  • Posterior fossa decompression surgery
  • Electrocautery
  • Spinal laminectomy

The aims of these surgical interventions are excessive pressure release from the brain and spinal cord; re-establish the normal CSF flow1,5.


  1. Chiari Malformation Fact Sheet; National Institute of Neurological Disorders and stroke; Retrieve from
  2. Chiari Malformation; WebMD; Retrieve from
  3. Chiari-Malformation Type 2; Genetic and Rare Diseases Information Center; Retrieve from
  4. Peyman Pakzaban; Chiari Malformation; Medscape; Retrieve from
  5. Chiari Malformation; Maya Clinic; Retrieve from

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