Most children will fully recover from a concussion within a few days, but many will have prolonged symptoms that can last for weeks or even months after their injury. This is known as post-concussion syndrome (PCS).
A 2011 study in the American Journal of Sports Medicine found that dizziness, the second most common symptom of PCS (headache is first) is the only on-field symptom of sports-related concussion predictive of PCS. The study also noted that high-school football players who experienced dizziness at the time they sustained their concussions were six times as likely to develop PCS as those who did not feel dizzy at the time of injury.
What is it about dizziness that is unique in concussion?
Inner ears and balance
There are many potential causes of dizziness following concussion, most of which result from the impact to the brain itself. However, there is a lot more real estate in the head than just the brain.
Two structures that are very sensitive to trauma and can cause dizziness when injured are the inner ears, which lie directly next to the brain on either side of the head. Each of our two-paired inner ears includes a hearing organ, called the cochlea, and five balance organs called the vestibular organs. The vestibular organs are motion sensors that sense movement and orientation.
Two otolith organs sense linear motion and three semicircular canals sense rotation in different planes. The inner ears take this information and send it to the brain, which compares and processes the information from both ears to help us feel oriented and stay balanced. The same information is also sent to our eyes to help keep our retinas still when we move our head; think of to the image-stabilizing function on a digital camera or smartphone.
Injury to the vestibular organs can cause a particular type of dizziness called vertigo, which involves a sensation of movement or spinning of one’s surroundings, as well as imbalance.
Guang Wei Zhou ScD, Talia Shoshany BS, and I recently retrospectively reviewed the medical records of all children and adolescents seen for dizziness in the PCS setting over a two and a half year period (109 patients altogether) in the Balance and Vestibular Program Clinic and Brain Injury Center Multidisciplinary Concussion Clinic at Boston Children’s Hospital Waltham. We found that we had identified a traumatic inner ear disorder in one out of every four patients (25.7 percent). Many of these children had been struggling with their dizziness for many months after their injury. Unfortunately, the diagnosis and treatment of these disorders was frequently delayed by limited awareness of traumatic inner ear disorders among primary concussion providers, who are typically sports medicine and neurology specialists that are not generally exposed to disorders of the ears.
The most common diagnosis identified was benign paroxysmal positioning vertigo (BPPV), which was present in approximately one in five of the patients with dizziness in the setting of PCS in this study.
Other diagnoses we identified were: temporal bone fracture (three patients), perilymphatic fistula (two patients), superior semicircular canal dehiscence (two patients), and labyrinthine concussion (two patients). In addition to dizziness or vertigo, these diagnoses can also be associated with severe imbalance, sound-induced vertigo, hearing loss and/or tinnitus (ringing in the ears). Many of these disorders are treatable with surgical repair or with a specialized type of physical therapy known as vestibular rehabilitation.
If any of the ear-related symptoms described above are present in the setting of prolonged post-concussive dizziness, then a careful examination of the ears and an audiogram (hearing test) should be considered. Often, specialized vestibular testing and a temporal bone CT are also required to diagnose certain disorders; when any of these disorders are suspected, referral to an otolaryngologist or a vestibular specialist should be considered.
Learn more about the Balance and Vestibular Program.