Chiari malformation is typically considered a congenital condition, although acquired forms of the condition (like from trauma) have been diagnosed. A Chiari malformation also commonly referred to as cerebellar ectopia
A German pathologist, Professor Hans Chiari, first described abnormalities of the brain at the junction of the skull with the spine in the 1890s. He categorized these in order of severity – types I, II, III, and IV. The term Arnold-Chiari was later applied to the Chiari type II malformation. On this site we will only be covering the type of Chiari that can be acquired (through severe whiplash/neck trauma) – Chiari I Malformation.
Acquired Chiari I Malformation is characterized by downward displacement by more than four millimeters, of the cerebellar tonsils beneath the foramen magnum into the cervical spinal canal (mine is 9mm below the foramen magnum on my MRI). This displacement may block the normal pulsations of CSF between the spinal canal and the intracranial space.
Several studies have suggested that a previously undetected Chiari I malformation can be “awakened” as a result of trauma caused during a motor vehicle crash. While these studies determined that head or neck trauma is capable of “triggering” symptoms relating to Chiari I malformations, in a 2010 study, Michael D. Freeman and number of other experts asked: could motor vehicle crash trauma actually be the sole cause of a Chiari I malformation? The answer is that it’s definitely possible.
Established research has already concluded that Chiari malformation can be acquired (i.e. non-congenital). In a procedure known as lumbar shunting, cerebrospinal fluid (CSF) levels are reduced in order to ease intracranial pressure in patients with neurological disorders, excessive drainage of spinal fluid from the lumbar or thoracic areas of the spine due to injury, exposure to harmful substances, or infection.
In some cases, reduced CSF levels can allow the brain to drop in the skull to the point that the cerebellum pushes through the foramen magnum, in effect causing a Chiari malformation. This occurs because the flotation level of the brain is dependent on the amount of CSF within the dural covering of the spine and brain. There is also clinical evidence showing that dural leaks causing reduced CSF levels are in fact associated with whiplash trauma. Accordingly, it is quite possible that whiplash trauma could cause a dural leak that results in Chiari I malformation.
Chiari Malformation Following an Auto Accident
Regardless of whether or not trauma from a wreck triggers preexisting asymptomatic Chiari I malformation or actually causes it, research indicates that symptoms of Chiari I malformations are substantially more prevalent in whiplash-injured patients. If you suffer head or neck trauma in a wreck, especially whiplash, you may develop symptoms resulting from a Chiari I malformation. With whiplash, the head moves violently forward then backwards. This is known as an acceleration/deceleration mechanism injury. During such, the cerebellar tonsils can pass through the opening at the bottom of the skull (known as the foramen magnum) and pass into the upper part of the neck. In a study published in the Journal of Brain Surgery written by Professor Michael Freeman and Dr. Ezriel Kornel, a correlation between acceleration/deceleration injuries and symptomatic Chiari was found after reviewing 1200 cervical MRI’s. The study illustrates that a pre-existing congenital Chiari often becomes symptomatic following a motor vehicle collision. Disruption of the CSF results in symptoms including dizziness and disorientation.
Type I—which may not cause symptoms—is the most common form of CM and is usually first noticed in adolescence or adulthood, often by accident during an examination for another condition. Type I is the only type of CM that can be acquired. (http://www.ninds.nih.gov/disorders/chiari/detail_chiari.htm)
Many individuals with the Chiari I malformation do not become symptomatic until adulthood, and the factors that contribute to the onset of symptoms have not been well characterized. ( http://www.ncbi.nlm.nih.gov/pubmed/18981886 )
What are the tests to diagnose a Chiari I Malformation?
Magnetic resonance imaging (MRI). An MRI uses powerful radio waves and magnets to create a detailed view of your body. This safe, painless test produces detailed 3-D images of structural abnormalities in your brain that may be contributing to your symptoms. It can also provide images of the cerebellum and determine whether it extends into the spinal canal. An MRI is often used to diagnose Chiari malformation.
A stand up MRI is recommended if possible as it shows Chiari more clearly. A regular MRI in a machine where you lay down is the most common ordered though as stand up MRI’s are not yet as prolific.
Computerized tomography (CT) scan. Your doctor may recommend other imaging techniques such as a CT scan. A CT scan uses X-rays to obtain cross-sectional images of your body. A CT scan can help to reveal brain tumors, brain damage, bone and blood vessel abnormalities, and other conditions.
What are the symptoms of Chiari I Malformation?
These structural abnormalities can lead to headaches as well as a variety of other neurological symptoms including:
- swallowing problems or speech problems such as hoarseness
- headaches – often severe, typically precipitated with sudden coughing, sneezing, or straining (usually at the back of the head, and are often made worse by exertion); it is important to remember that trye migraine headaches are rarely caused by Chiari I Malformations
- neck pain and stiffness
- muscle weakness
- Unsteady gait (problems with balance)
- Poor hand coordination (fine motor skills)
- numbness in arms, legs, or face
- vision problems
- spasticity of the limbs
- sudden “drop attacks” where the legs seem to buckle for no reason
- Scars called adhesions may form over time at the site of compression, resulting eventually in a gradual onset of symptoms. A whiplash-type injury or other accident or trauma may cause sudden onset of symptoms
- spinal curvature
- the most serious complication is a Syringomyelia or syrinx (a cyst within the spinal cord); this may cause weakness, numbness, tingling and/or clumsiness involving the upper and lower extremities
Less often, people with Chiari malformation may experience:
- Ringing or buzzing in the ears (tinnitus)
- Slow heart rhythm
- Curvature of the spine (scoliosis) related to spinal cord impairment
- Abnormal breathing, such as central sleep apnea, characterized by periods of breathing cessation during sleep
Symptoms may be worse when the neck is flexed or extended.
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