Chiari Malformation

Imagine if someone told you- “If you laugh or sneeze too hard, your brain may pop out of your skull!” Well, yes, this seems like a very distant endeavour for any normal human being, but patients suffering from a condition called Chiari Malformation would likely concur on the same.

Chiari malformations are the structural defects in the base of the skull and cerebellum (the part of the brain that controls balance). Here, the cerebellum bulges through an opening in the cranium, where it joins the spinal canal. As a result, pressure is created on parts of the nervous system leading to severe to mild to no symptoms.

These may develop when part of the skull is smaller than usual or misshapen, which presses on the brain and forces the cerebellum to be pushed down into the spinal canal (see Figure 1.). This pressure on the cerebellum and brain stem, thus, affects the various functions administered by these areas and blocks the flow of cerebrospinal fluid (CSF)-the clear liquid that surrounds and cushions the brain and the spine.

“I started to have spasms in my diaphragm that would make me gasp and have hiccups constantly. I began to stutter as I had lost all control of the muscles for speech. Jerking movements such as during a fit of giggles could cause my brain to herniate into the top of the spinal column raising the risk of sudden deaths.” – Hailey Dickson, Social & Community Content Producer at Khan Academy quotes amidst her teenage crisis of being diagnosed with Chiari Malformation Type I.

CAUSES OF CHIARI MALFORMATIONS

The exact cause is still unknown; such structural defects in the brain may often occur during foetal development, which in turn result due to the consumption of harmful substances or an injury during pregnancy. Alternatively, it may be linked to the genetic problems that run in families. Such a CM is called primary or congenital Chiari Malformation.

Moreover, another cause of the same is excessive spinal fluid draining from the lumbar (lower back) and thoracic (chest) areas of the spine either due to traumatic injury, disease, or infection. This is called secondary or acquired Chiari Malformation.

 HOW CAN CMs BE CLASSIFIED?

Chiari malformations can be classified based on two factors:

1. The severity of the disorder
2. The parts of the brain that protrude into the spinal canal

When the lower part of the cerebellum, also known as cerebellar tonsils, pushes into the spinal opening called the foramen magnum, it results in Chiari Malformation Type I the most usual form of the condition. It is often diagnosed in patients during adolescence or adulthood, often by accident during an examination for another condition.

Others include Chiari Malformation Type II (also called Classic CM), where both the brainstem tissue and cerebellum protrude into the foramen magnum, and Chiari Malformation Type III where the cerebellum and the brainstem tissue stick out or herniate through an abnormal opening in the back of the skull which is what referred to as the “brain falling off the skull”.  The last type is Chiari Malformation Type IV, which involves an incomplete or underdeveloped cerebellum; thus, parts are missing, resulting in portions of the skull and spine being exposed.

SIGNS & SYMPTOMS OF CM

Some individuals with this condition may remain asymptomatic for a long period. The compression of the tissue and the build-up of the CSF pressure influence the symptoms produced in such defects. The following symptoms can be observed in patients with CM:

1. Headaches

Undiagnosed CM type I leads to severe headaches, especially on sheer exertion and after sudden coughing, sneezing, or straining.

• Spinal Curvature

The individuals may develop an abnormal, lateral curvature of the spine, i.e., bending either left or right (scoliosis) or bending forward (kyphosis).

• Sleep Apnoea

“Apnoea” refers to the state of ceased breathing during sleep. This symptom may develop into a severe sleep disorder characterised by recurrent sleep interferences.

• Other common symptoms include-
• Hoarseness
• Hearing or balance issues
• Nausea
• Ringing or buzzing in the ears (tinnitus)
• Excessive drooling or gagging
• Difficulty swallowing or speaking
• Dizziness
• Rapid, side-to-side eye movements (nystagmus)

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Dorothy Pope, the Director of the Chiari and Syringomyelia says about 3 million people develop this condition in the US with symptoms, severity and treatments varying in each case. She also quotes, “Chiari Malformation is uncommon but increased use of imaging tests has led to a more frequent diagnosis.”

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DIAGNOSIS

No test is available to check the presence of CM in the foetus, [AA1] [KJ2] but some of the malformations associated with this defect can be observed via ultrasound. Most patients with Chiari Malformations are asymptomatic until the malformations are discovered during another diagnosis or treatment. In addition, the specialist shall also conduct a physical assessment of the individual to check the person’s memory, cognition, balance (controlled by the cerebellum), touch, reflexes, sensations, and motor skills (controlled by the spinal cord). The two tests that can be done to diagnose are MRI (Mental Resonance Imaging) and CT scan (Computed Tomography scan).

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“September is Chiari Malformations Awareness Month, an illness that affects one to two per cent of the population around the globe, making it uncommonly special to deal with.”

–Gerald Grant, MD, division chief of paediatric neurosurgery

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HOW CAN CM BE TREATED?

The treatment of the individual is usually undertaken by a neurologist and neurosurgeon based on four factors: symptoms, age, general health, and severity of the condition.

Individuals with CM who do not show any symptoms and do not interfere with a person’s everyday living may require frequent doctor examinations and medicines to ease the headaches and general body pain.

When the condition becomes utterly severe, surgery is the only way out. It facilitates easing the symptoms or halting the progression of damage to the central nervous system. Unfortunately, the stabilization of symptoms may also require more than one surgery

BASIC TAKEAWAYS:

• In patients with Chiari Malformations, the bottom portion of the brain dips down through an opening at the lower part of the skull.
• Type I is the most generic form of Chiari Malformations.
• In most cases, the problem remains undiagnosed till adolescence or adulthood and is congenital (present by birth).
• The individual may not show any symptoms. However, the most common ones would be headaches or pain in the back of the neck, which can worsen during sneezing, laughing, and coughing.
• The individual may develop a pocket of spinal fluid in the spine or brain stem. This is referred to as syrinx.
• The individual may be suggested to undertake tests like MRI or a CT scan to ease the process of diagnosis and facilitate preliminary treatment.

Reviewer: Areeba Azeez