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Hidden Injury Series: Cerebellar Tonsilar Ectopia after Whiplash

The Hidden Injury Series: In this series of articles, we review potential causes of chronic symptoms after a whiplash type injury. These injuries are not commonly diagnosed by traditional physicians, and many cases are inappropriately attributed to mental health problems. The correct exam and a knowledgeable doctor may be able to help. Today we cover cerebellar tonsilar ecptopia.

Cerebellar tonsilar herniation or cerebellar tonsilar ectopia (CTE) is a condition in which the base of the brain begins to descend down through the skull and into the spinal canal. You may know these findings as a condition called Arnold Chiari malformations. The severity of this displacement of brain tissue can vary, and is usually classified into 4 types:

  • Chiari I – Small protrusion of the cerebellum into the foraman magnum
  • Chiari II – Larger protrusion involving the cerebellum and brainstem into the foramen magnum. Considered to t be the classic form of Chiari and is associated with the development of a spinal cord syrinx.
  • Chiari III – a rare and sever form of Chiari which prounounced herniation. Associated with tethered cord and pronoucned neurologic deficits
  • Chiari IV – rare form of chiari where the cerebellum is significantly underdeveloped.

Chiari II is the most common clinically relevant form of Chiari. It can be asymptomatic which makes its true prevalence unknown, but it can be tied to symptoms such as:

  • Neck pain
  • Hearing/balance problems
  • Difficulty swallowing
  • Weakness
  • Dizziness
  • Tinnitus
  • Ataxia
  • Drop attacks

Most chiari malformations are thought to be congenital and exist from childhood. However, Chiari I malformations can be secondary and induced by things like spinal taps, infection, and even…..traumatic injury.

Whiplash and Cerebellar Tonsilar Herniation

A 2010 study published in the journal Brain Injury found that a significantly higher proportion of patients involved in motor vehicle accidents met the MRI criteria for a chiari malformation.

The study recruited 1200 patients with 600 involved in an accident and 600 controls. They also wanted to observe if there were any differences in findings when an upright MRI was used compared to a recumbant MRI.

The results were pretty astounding.

In the non-trauma control group, both the upright and recumbent MRI showed 5.3% and 5.7% of the subjects met the criteria for chiari malformation.

However, in the trauma group, the numbers increased significantly. In the recumbent MRI, 9.8% of the scans showed cerebellar tonsilar ectopia (CTE) which is a pretty large increase from the non-trauma population. However, subjects that received an MRI in a seated position showed that 23.3% of the scans showed CTE!

That is a massive difference! Considering that the vast majority of MRI scans are performed lying down, there could be a large number of people who have received an MRI but have no idea that they have a chiari malformation.

So what? They might be asymptomatic

We know that many of these ectopias can be asymptomatic so, when it comes to identifying these types of injuries, it’s important to correlate them with clinical findings.

What’s unique about whiplash injuries is that many patients will go to their doctor with complaints of headache, dizziness, and other new and unusual symptoms. When these patients are sent for diagnostic imaging and other tests, they often come back empty handed. Many of these patients then get diagnosed with a non-specific pain disorder, or are told that their symptoms are likely psychogenic.

There’s no doubt that mental health can play a role in many accident cases. However, a thorough neurological exam can reveal subtle signs cranial nerve and brain related dysfunction. This can include:

  • Eye movement abnormalities and nystagmus
  • Asymmetric uvula/tongue deviations
  • Subtle signs of ataxia and dysmetria
  • Persistent deficiencies in balance exams

While these tests aren’t necessarily diagnostic of a chiari malformation, they can help paint a more complete clinical picture for why a patient may not be responding well to treatment.