Dizziness & Vertigo

The most common cause of dizziness is injury to the tissues of the neck. When the ligaments and discs of the neck are injured, inflammation and scar tissue can affect the nerves of the spine that help us regulate balance. In fact, recent studies show that most patients suffer from balance problems after an auto accident, even if they don’t have symptoms of dizziness.

Vertigo and balance problems can come from a variety of sources, including blood pressure, the inner-ear, eyes, brain or the muscle and joints of the neck. Often these areas in the neck have receptors that help tell our body where we are in space. If these receptors and our other clues that help orient our balance are not communicating effectively, we can experience vertigo. Our doctors will help determine the possible causes of vertigo in your individual case.

How we can help with these symptoms:

Here are some important articles that explore the issue of dizziness and vertigo after an auto collision:

Postural Stability and Neck TraumaProprioception and WhiplashMore on Proprioception and WhiplashObjective Evidence of Nerve and Muscle Changes after Whiplash InjuryWhiplash: The Neck and the BrainWhiplash and Postural Control Disturbance
Dizziness and vertigo are common symptoms of whiplash injuries. The issue of posture control is a relatively new area of study in the field of whiplash injuries, but one that is providing many new clues into the nature of such injuries. Because postural control is such a complex mechanism, much can be learned about the nature of whiplash injuries if we can understand what aspects of the postural control system are altered after an injury.

There are three components to the Postural Control System:

The Visual System provides information to the brain on where the body is positioned in space.
The Vestibular System consists primarily of the inner ear, and provides information to the brain on the motion of the head.
The Somatosensory portion of the PCS informs the brain of the position of the body. Organs and receptors in the muscles and joints of the body perform this function, which is commonly referred to as “proprioception.”
Most of the research on the problem of dizziness after whiplash has been focused on proprioceptive dysfunction. Injury to proprioceptors in the cervical spine could lead researchers to understand exactly what kind of injury mechanism is responsible for whiplash pain and symptoms.

The goal of this current study was to see if there was a difference in balance between healthy subjects and patients with neck trauma. The researchers performed postural stability tests on 32 healthy subjects (no neck complaints or reports of vertigo), and ten whiplash patients. None of the subjects were told the purpose of the study. The healthy subjects were divided into five groups, by age (20s, 30s, 40s, and 50s).

The graph on the following page shows the results between the five groups of subjects.

The researched found two interesting pieces of information. First, all of the subjects had more trouble maintaining balance with the head in the backwards position. Secondly, whiplash patients had significantly reduced postural control functioning.

The authors conclude, “Patients with a whiplash injury and subjective neck complaints have impaired postural control compared with control subjects.”

This seems to be a fairly objective test, since the test subjects did not know what was being studied, making it more difficult to “fake” results.

Further research will need to be done to determine the nature of these postural disturbances in whiplash patients.

postural stability

Kogler A, Lindfors J, Odkvist LM, Ledin T. Postural stability using different neck positions in normal subjects and patients with neck trauma. Acta Otolaryngologica 2000;120:151-155.

Over the last few years, a number of researchers have investigated the role of proprioception in the problem of whiplash. Some researchers have hypothesized that injury to the cervical facet joints may result in dysfunction of that part of the nervous system responsible for balance. (For a review of these studies, see our book Low Velocity Whiplash Biomechanics.)

A recent study again looked at this problem by studying the cervical movements, the cervical range of motion, and the oculomotor function of 27 whiplash patients. They compared these patients to 25 healthy control subjects, and found significant differences. They found that, “Repositioning dysfunction was present in 62% of subjects with whiplash trauma 2 years after the trauma.” They also showed dysfunction in the oculomotor tests, indicating that “restriction of cervical movements and changes in the quality of proprioceptive information from the cervical spine region affect voluntary eye movements.”

These dysfunctions could possibly result in dizziness or vertigo—a common symptom of whiplash injury—and also may indicate that if the proprioceptive function of the nerves in the facet joints are injured, the nociceptive—or pain carrying—nerves may also be involved as well. This could explain the chronic neck pain experienced by whiplash patients.

“Previous studies illustrate the presence of mechanoreceptive and nociceptive nerve endings in cervical facet capsules proving that these tissues are monitored by the central nervous system and implying that neural input from the facets is important to proprioception and pain sensation in the cervical spine. In our study significant correlations occurred between active range of cervical motion and oculomotor performances as well as kinesthetic sensibility, which could indicate that the zygapophysial joints’ dysfunction mediates this proprioceptive dysfunction.”

The authors conclude:

“These results point to a multifactorial background of the chronic morbidity after whiplash trauma. However, a proprioceptive dysfunction might be one of the most important factors for understanding the morbidity after a noncontact whiplash trauma to the neck.”

Heikkila HV, Wenngren BI. Cervicocephalic kinesthetic sensibility, active range of cervical motion, an oculomotor function in patients with whiplash injury. Archives of Physical Medicine and Rehabilitation 1998;79:1089-1094.

Many studies have been recently published that have explored the relationship between whiplash and proprioception. A new study adds more to this research, by seeing how well whiplash patients could reproduce their head position in an experimental setting, as compared to a group of healthy control subjects.

Eleven whiplash patients were evaluated in this study; at least three months had passed since the injury before the test was performed. The patients wore a cervical range-of-motion device (CROM), and their heads were positioned at 30° of right rotation by the researcher. With the test subjects eyes closed, the researcher positioned the patients head at 0°, and then instructed the patient to return his or her head to the 30° position three times, without opening his or her eyes. Five other test positions were evaluated as well, and the same test was given to eleven healthy control subjects.

“The whiplash group averaged an absolute difference of 5.01° from their recorded angle measure compared with the true angle measure, whereas the control group averaged a 1.75° absolute difference.”

The authors conclude, “Individuals who have sustained a whiplash injury may have proprioceptive deficits that do not allow them accurately or reliably to calculate head position. This may be detrimental to their everyday function…Rehabilitation after whiplash injury should focus not only on range of motion and strength but on postural awareness.”

Loudon JK, Ruhl M, Field E. Ability to reproduce head position after whiplash injury. Spine 1997;22(8):865-868.

One of the problems with whiplash diagnosis for many years was the lack of objective evidence of injury. Recent studies, however, have given us new tools that we can use to pinpoint organic lesions in many patients.

Muscle Injury After WhiplashNow, two new studies show that neck muscles show objective, anatomical changes after whiplash injury.

Muscle Injury After Whiplash
The first study set out to see if there were detectable changes in the neck muscles of whiplash patients. Previous studies have shown that patients with spinal pain also show fatty infiltration of the muscles on MRI. The authors of this study studied 79 female whiplash patients and 34 healthy control subjects, all between the ages of 18-45. Each subject had a neck MRI focused on the cervical spine muscles.

The authors found:

Whiplash patients had significantly larger cross section of the deep multifidus muscles at the C3-C7 spinal levels.
Other spinal muscles in the whiplash patients showed an increase in size as well.
There was no correlation between fatty infiltration and BMI or age.
Symptom duration or severity did not seem to affect the degree of muscle changes.
The authors write that these, “alterations in the deep muscles may provide valuable insight into the common functional impairments observed in patients with persistent whiplash.”

Because these deep muscles play a critical role in postural control and balance, disruption of these muscles may result in other symptoms of whiplash, such as dizziness or vertigo.

The changes in muscle were found to occur as quickly as three months after injury.

Whiplash Different from Other Neck Pain

The same group of researchers decided to perform another study2 that compared the difference between whiplash patients and people with “chronic, insidious-onset neck pain.” Their theory was that if disuse of the neck muscles was responsible for the fatty deposits in the muscle, it should be found in patients with non-traumatic neck pain as well as whiplash patients.

The study examined 23 women with chronic neck pain. Each subject was imaged with MRI, and was tested with pressure and thermal pain threshold tests.

The authors of the second study found that, “the results of this study provide preliminary data that female patients (18-45 years) suffering from persistent insidious-onset neck pain do not show quantifiable MRI changes in the fat content of the cervical extensor musculature and that their levels of fat mirror those with no history of neck pain. In addition to a lack of muscle changes, participants with insidious-onset neck pain did not demonstrate widespread sensitivity to sensory stimuli and the presence of these features is consistent with abnormal central pain-processing mechanisms; such as seen in some subjects with acute and chronic WAD.”

These studies provide important insight into the problem of whiplash:

– Motor vehicle collision patients show objective evidence of muscle changes on MRI.
– Whiplash injuries are different from non-traumatic neck pain.
– Because fatty infiltration occurs only in whiplash patients, the cause of this phenomenon may be damage to the nerves of the spine.

Elliott J, Jull G, Noteboom JT, Galloway G. MRI study of the cross-sectional area for the cervical extensor musculature in patients with persistent whiplash associated disorder (WAD). Manual Therapy 2008;13:258-265.
Elliot J, Sterling M, Noteboom JT, Darnell R, et al. Fatty infiltrate in the cervical extensor muscles is not a feature of chronic, insidious-onset neck pain. Clinical Radiology 2008;63(6):681-687..

There is a wide range of whiplash symptoms. The most common, of course, are neck pain and headache, but a substantial percentage of patients report other, more difficult to understand problems as well. Some of these symptoms include dizziness; problems with balance; difficulties with attention and concentration; and sleep disturbances.
Brain injury and whiplash

A number of theories have been put forth to explain these myriad symptoms. Some researchers have suggested that brain injury is responsible, while the insurance industry insists that these symptoms are fabricated.

A recent study1 from Sweden attempts to answer some of these questions by examining the functions of the brain in whiplash patients.

The study started with 40 patients with grades II and III whiplash injuries. The patients were given neuro-otological tests within two months of the injury and again two years later.

Brain injury and whiplash
These tests included auditory brainstem response tests (ABR) and oculomotor function tests, including evaluation of saccades (the rapid, step-like voluntary motion of the eyes used when reading or scanning an image).

ABR tests involve measuring the patient’s neurological response to a repetitive sound stimulus
“A brief sound causes a series of electrical waves, in the nanovolt range, that can be recorded from the surface of the head. The signals are so small that they are normally buried in background electrical noise, but when the same brief stimulus is presented many times and the responses are averaged, the waves can be measured reproducibly. Early peaks in the waveform represent electrical activity in the eighth nerve arriving at the cochlear nuclei, and later peaks represent combined activity at successive sites in the auditory pathway.” 2

By analyzing the waveform, it is possible to identify dysfunction along the neurological pathway.

At the two-year follow-up, 16 of the patients (40%) had no symptoms from the original injury. Ten patients (25%) complained of intermittent neck pain, headache, and radiating pain in one or both arms. Four patients (10%) also reported memory impairment, concentration problems, and showed neurological deficits. Another 4 patients (10%) were still on sick leave.

In the smooth pursuit tests, 5 patients showed abnormalities in the first test. Three of these patients improved, but two showed worse results at the two-year follow-up. These two patients who worsened over time also showed problems with their ABR tests.
Ten patients showed a worsened score on saccade velocity at the two-year follow-up.

What is at the root of the chronic pain and the neuro-otological signs? The authors suggest two possible explanations: altered neurological responses of the brainstem, and direct trauma to the brainstem.

The first explanation would describe the symptoms of most chronic whiplash patients and works as follows: The cervical spine plays a key role in how the brain maintains balance, and signals from the injured cervical spine travel through the spinal core to the brainstem—specifically the vestibular and oculomotor nuclei. This is the same part of the brain that receives the signals from the inner ear, via the eighth cervical nerve. A painful neck can cause overexcitation of the nerve pathways, resulting in altered functioning of the brainstem. These alterations in the brainstem can in turn cause dysfunction in eye motility and balance, since these different systems all work together as the Posture Control System.

Most patients with chronic whiplash pain and ocular and auditory signs would fit in this category. However, this mechanism may not account for those patients with the most severe symptoms: “In the present study, we found two patients with pronounced pursuit abnormalities compatible with organic brain/brainstem lesions.”

So, according to this small study, about 2% of whiplash patients have signs of brainstem damage. This may seem like an insignificant number, but when we consider that there are approximately 1 million whiplash injuries in the US each year, there may be 20,000 cases of brainstem injury from auto collisions annually.

This study provides two important pieces of information about chronic whiplash: the first is that ABR and saccade tests are an objective way to measure altered neurology in these patients; the second is that some patients may have actual brain injury from these collisions.

For patients with more severe symptoms, it may be advisable to have them evaluated for saccade movements and ABR by an audiologist.

Wenngren BI, Pettersson K, Lowenhielm G, Hildingsson C. Eye motility and auditory brainstem response dysfunction after whiplash injury. Acta Otolaryngologica 2002;122:276-283.
Nolte J. The Human Brain: An Introduction to Its Functional Anatomy. 2002, Mosby, p. 355.

Symptoms of vertigo, dizziness, and visual disturbance are common after whiplash injuries. A group of researchers recently studied patients with these symptoms, focusing specifically on the proprioceptive functions of the cervical spine.

Twenty six patients were studied, 23 of whom had been in a rear-end collision. The average time since the accident was 4.7 years, and all patients had been active employees or students at the time of the accident. A thorough neurological examination had been performed on each patient, including CT and MRI scans of the neck or brain. “There was neither neurological nor radiological evidence of any CNS injury in any of the subjects.” All of the test subjects were compared to a matched control group of asymptomatic people.

The researchers studied:

Eye movements during reading. This test was used to study eye behavior.
Caloric tests—used to test for proper or disturbed functioning of the vestibular, pontine, and cerebellar brain functions.
Visual evoked potential tests were done to study occipital lobe function.
Auditory brainstem response was analyzed to test the cochlear nerve, the pons, and the mesencephalon.
A saccade test was performed to test the function of the paramedian pontine reticular formation, the pons, mesencephalon, basal ganglion, midcerebellum, and frontal lobe.
The Smooth Pursuit Neck Torsion Test (SPNT)—used to study the smooth pursuit system and the proprioceptive function of the cervical spine.

The authors found that there was no difference between the whiplash patients and control group subjects on visual evoked potentials, caloric tests, brainstem audiometry, and saccade test.
The study found significant differences between the two groups on the SPNT. The authors state that, “it is likely that all but 2 of the patients had a posture injury.”
There were significant differences between the two groups on reading behavior. In fact, the whiplash patients showed reading behaviors similar to children in the first three years of elementary school, while the control subjects showed behaviors in the high school range! These reading problems were found to be closely linked to problems with smooth pursuit.
By examining many different functions, the authors were able to analyze exactly which neurological functions, if any, were responsible for symptoms of vertigo, dizziness, and reading problems. “In a consecutive group of [whiplash] patients, we have documented disturbed control of saccadic eye movements during reading as well as of the smooth pursuit eye movements. This last effect was augmented by neck torsion. After a systematic discussion and elimination of other explanations, this is interpreted as being caused by distorted neck proprioceptive activity which sends misleading information to the posture control system. It is reasonable to interpret the impairment as a result of the [whiplash] trauma.”

This study contains an excellent review of the different components of the postural control system, and anyone interested in this aspect of whiplash trauma would be well served by obtaining a copy of this article.

Gimse R, Tjell C, Bjorgen IA, Saunte C. Disturbed eye movements after whiplash due to injuries to the posture control system. Journal of Clinical and Experimental Neuropsychology 1996;18(2):178-186.