Can Head Trauma Cause Essential Tremor?

It seems like nearly every day brings some new health issue to be concerned about. If it isn’t mosquito-borne disease, it’s distracted drivers on their cell phones. Then there’s head trauma. This was brought to popular awareness by the movie “Concussion,” based on a real-life story about the doctor who identified extreme brain damage among NFL football players. He called it chronic traumatic encephalopathy (CTE), and it ravages a person’s brain. A recent news story told how examination of 111 deceased NFL players’ brains led to the revelation that 110 of them had CTE.

It’s a scary, sobering report, yet the movie did not trigger widespread anxiety among us non-athletic types. After all, who among us has an occupation that involves severe repeated brain-battering like hard-hitting football does?

It’s easy, therefore, to not include head trauma on our list of daily anxieties, but in fact traumatic brain injury (TBI) is more common than we think. The U.S. Centers for Disease Control (CDC) says that everyone is at risk, especially children and older adults; in 2013, there were about 2.8 million TBI-related emergency room visits and hospitalizations. The CDC defines TBI as “a bump, blow, or jolt to the head that disrupts the normal function of the brain.” The injury can range from severe to mild, and most concussions are in the moderate-to-mild category.

Since I keep an eye on medical news, my email is bringing an uptick in items on head trauma in connection with movement disorders. I decided to look into it more.

Traumatic brain injury

It is generally accepted that a severe brain injury due to a blow to the head can lead to movement disorders, including tremors and other symptoms associated with disruption of the brain’s movement (motor) circuitry. The statistical incidence of movement disorders after severe head injury ranges from 13-66%. With regard to essential tremor (ET), a published study by Benito-León, et al. (2015) reported that out of 274 individuals with ET, 32 (11.7%) had a history of serious head trauma. Compared with a control group (no ET), “participants who reported serious head trauma were 52% more likely to have ET.”  This research team found that age at the time of injury made a difference. Those who were over 40 at the time of brain trauma were at greater risk of developing ET.

But this study doesn’t raise much anxiety. Despite the CDC statistics, we don’t expect to have a severe TBI. However, the news in my in-box suggests that even less severe head injury can lead to tremors.

Moderate or mild head injury and ET

Here are a few examples of research reports that linked moderate or mild head injury with ET.

1. A German team contacted 158 patients 4-6 years after they had moderate or mild head injury. Sixteen of them (10.1%) had developed movement disorders most like related to brain trauma, though not severe. “The most frequent finding was a low-amplitude postural/intention tremor that appeared to resemble enhanced physiological or essential tremor.”
2. An older University of Chicago observational study described tremor brought on by mile head injury without loss of consciousness. Tremor appeared from 1-4 weeks after the trauma, and it was postural and action-triggered, affecting the hands and/or head. There were no other neurologic symptoms, and neurologic imaging was normal. Three patients experienced tremor reduction on clonazepam, the propranolol helped on other. The authors concluded, “A tremor, similar to essential tremor, can be a rare complication of head trauma.”
3. A very recent news report explains that while moderate to severe brain injury has been linked with developing Parkinson’s disease, the evidence for mild trauma has been inconclusive. This report states, “People who have been diagnosed with a mild concussion, or mild traumatic brain injury, may have a 56 percent increased risk of developing Parkinson’s disease, according to a study published in the April 18, 2018, online issue of Neurology®…” While this particular study tracked mild TBI in connection with Parkinson’s, it gives us cause to wonder how many people developed tremors, even temporarily, after a relatively mild blow to the head.

To return to the question of whether head trauma can cause ET, I think the short answer must be yes, it can. The more severe the injury, and the older the person, the greater the possibility. However, I found one more published article that assures us, “In cases of mild to moderate head injury, the incidence of movement disorders is much lower, occurring only transiently [temporarily] in 7.6% of the cases and persistently in 2.6% of the patients.” In other words, you probably have a better chance of dodging an erratically driven SUV whose driver is texting than you do of having a bump on the head that causes tremors.

If, however, you have ET (regardless of the cause) that does not respond to medication, contact our Center for information on a noninvasive procedure called Neuravive to control hand tremors.

i. Joe Ward, Josh Williams, Sam Manchester, “110 N.F.L. Brains.” NY Times, Jul. 25, 2017. https://www.nytimes.com/interactive/2017/07/25/sports/football/nfl-cte.html

ii. Oh, IJ. Movement disorders in brain injury. Undated powerpoint presentation at https://www.scripps.org/assets/documents/34a_movement_disorders_oh.pdf

iii. Benito-León J, Louis ED, Labiano-Fontcubert A, Bermejo-Pareja F. Serious head trauma preceding essential tremor: A population-based study (NEDICES). J Neur Sciences. 2015 Jun;353(1-2):116-21.

iv. Krauss JK, Tränkle R, Kopp KH. Posttraumatic movement disorders after moderate or mild head injury. Mov Disord. 1997 May;12(3):428-31.

v. Biary N, Cleeves L, Findley L, Koller. Post-traumatic tremor. Neurology. 1989 Jan;39(1):103-6.

vi. Jack E. Hubbard and Samuel D. Hodge, Jr., A Whole Lot of Shakin’ Going On: Movement Disorders Caused by Brain Trauma, 65 Clev. St. L. Rev. 287 (2017) available at http://engagedscholarship.csuohio.edu/clevstlrev/vol65/iss3/5