Video Nystagmography to Monitor Treatment in Mild Traumatic Brain Injury: A Case Report

Abstract

This case report follows a patient with mild traumatic brain injury who was successfully treated using chiropractic care with chiropractic functional neurological rehabilitation applications. Video nystagmography (VNG) assessment was used as a diagnostic tool to detect aberrant eye movement. The patient was found to have dysfunctional rotational vestibulo-ocular reflexes, poor gaze stability, dysfunctional vertical extraocular pursuits, and inadequate vertical optokinetic responses. Based on the hypothesis that dysfunctional eye movements could be the source of many of this patient’s persistent postconcussive symptoms of nausea, fatigue, headaches, and reading difficulties, a course of specific chiropractic and brain-based applications was implemented as dictated by the physical examination and VNG findings. Following 2 wk of care, a follow-up VNG assessment demonstrated improvements in eye movement that correlated with the patient’s complete resolution of symptoms.

The incidence of concussions in the United Stated from sports and recreational activities is estimated to be 1.6 to 3.8 million cases annually.¹ Postconcussion syndrome (mild traumatic brain injury, or mTBI) represents a myriad of symptoms that may include headaches, fatigue, blurry vision, foggy thinking, reading difficulties, cognitive challenges, balance issues, trouble sleeping, and mood changes.² Females are more prone to postconcussion syndrome than males.³ Although the symptoms of 80% to 90% of concussion victims resolve on their own during the first 10 days postinjury, the remainder may have postconcussion symptoms that last from weeks to years.⁴

As many patients with postconcussion syndrome report symptoms related to visual disturbance, it follows that video nystagmography (VNG) may be a useful tool in evaluating eye movements that may have become dysfunctional as a consequence of a head injury.^5,6 It could also prove to be a helpful device in developing specific rehabilitation programs for particular individuals based on their VNG results and overall clinical picture. Finally, VNG could also be used in demonstrating treatment efficacy.

Patient Information

A 19-year-old female, Caucasian, college student presented on January 5, 2015, with a 2-month history of postconcussion symptoms following being hit on the left side of her head by a soccer ball in October 2014. Shortly thereafter, she began to have daily symptoms consisting of headaches, nausea, fatigue, difficulty reading or thinking, and jaw pain. Her symptoms were worse with shopping, walking, exercising, watching television, or walking downstairs. She had been experiencing jaw pain for the last 18 months after knocking heads with her brother, but her jaw pain had worsened since the soccer injury. Her symptoms became so severe and persistent that she had to take a leave of absence from her university in another state and move back in with her parents a few weeks later. She was diagnosed with a concussion by a medical neurologist from Oregon Health Sciences University in November 2014. No recommendations were given other than to rest. This patient had a concussion 9 years previously but had no apparent residual effects. She had no symptoms and was functioning normally prior to the October 2014 event.

Timeline.

Clinical Findings

Initial physical exam findings revealed a tender articular fixation of the left temporo-mandibular joint (TMJ) as well as asymmetrical opening and closing of the jaw. Palpation of the internal and external muscles of mastication revealed moderate-severe tenderness and hypertonicity on the left and moderate tenderness and hypertonicity on the right. There was an accentuated response to pinwheel perception throughout the right upper extremity and the right V1–V3 distributions of the face. The tongue deviated to the left upon protrusion. She had moderate palpatory tenderness and hypertonicity of the anterior muscles above T6 and the posterior muscles below T6. She had aversion to leftward optokinetic stimulus and was unable to watch the stimulus move to the left at all. She had a gradual decrease in refixation saccade amplitude with rightward optokinetic stimulus. She had poor vertical optokinetic responses and tended to nod her head up and down while following a vertical optokinetic stimulus whether it was moving upward or downward. Infrared oculography revealed an absent right rotational vestibulo-ocular reflex (r-VOR) and a poor left r-VOR. VNG confirmed the poor vertical and rightward optokinetic responses that were found in the physical examination. She was able to perform leftward optokinetic testing with the VNG, although she found it to be very fatiguing. VNG testing additionally revealed poor vertical pursuits, inability to hold downward gaze, and difficulty holding the eyes still at rest without a point of fixation.^7,8

Optokinetic (OPK) Responses

As the patient observes an optokinetic stimulus of alternating red and black stripes moving quickly in a particular direction, a reflexive eye movement referred to as optokinetic nystagmus is produced. Normal optokinetic nystagmus tracings appear as a saw-tooth pattern.

Intervention

Treatment consisted of chiropractic care and chiropractic functional neurological rehabilitation applications that were performed in 6 sessions in the course of 11 days. These included chiropractic adjustments using manual and instrument techniques, massage therapy, multiplanar right extremity exercises, therapeutic eye exercises, and right warm air caloric stimulus.

Chiropractic manipulation of the left TMJ was administered using an Activator I adjusting instrument.⁹ This was followed by massage therapy to the bilateral muscles of mastication. Spinal and extraspinal chiropractic adjustments were performed to the right side of the patient’s body using manual, high velocity, low amplitude manipulations.^10,11

Passive multiplanar movements of the right upper and lower extremities were performed where the practitioner would individually move the patient’s right arm or leg in an “infinity sign” pattern for 10 repetitions for 2 to 3 sets. During the first week of care, the exercise was performed with the patient’s right leg and the patient’s right arm was used during the second week of care. The patient was shown on the second week of care how to actively perform these exercises herself at home.

Therapeutic eye training exercises included gentle, left rotational head thrusts with central fixation immediately followed by optokinetic stimulus for 5 seconds, 12 seconds rest, and then repeated for 8 repetitions. The final optokinetic stimulus was in a rightward direction, while the previous optokinetic stimuli were in a leftward direction. This exercise was performed only for the first 2 days of care.

Vertical optokinetic and smooth pursuit eye exercises were also given. A vertical optokinetic stimulus was viewed for 5 seconds at a time with 10-second rest for 5 mini-sets. Direction of the stimulus, upward or downward, depended on the patient’s tolerance on each individual day. Vertical smooth pursuit exercises were given at different rates of speed to address the weaknesses found in the VNG assessment.^12,13 On days where she was not receiving care, she was to perform these eye exercises at home 2 to 3 times per day.

Right warm air caloric stimulus was administered using an ATMOS Varioair (ATMOS, Allentown, PA, USA). The Varioair allows for “dry” thermal examination of the vestibular organ by means of air. This device is typically used in the diagnosis of vestibular conditions but was used therapeutically in this case. Warm air at 48°C was applied into the right ear canal for 60 seconds for 3 repetitions. This therapy was only used during the second week of care.

The practitioner was careful to not exceed the patient’s metabolic capacity to tolerate any of these applications by observing for signs of autonomic stress brought on by anaerobic neuronal metabolism such as increased pulse, pupil dilatation, or sweating.¹⁴

Outcomes

Two days after the first visit, infrared oculography was again performed and revealed that the bilateral r-VORs were functioning normally. A repeat VNG was performed after the first week of care that demonstrated improvement in vertical pursuits, vertical optokinetic responses, rightward optokinetic responses, and spontaneous nystagmus without fixation. At various points in the course of treatment, other signs and symptoms began to improve, such as normalization of sensitivity to pinwheel perception on her right face and upper extremity, a decrease in her TMJ pain and dysfunction, and less aversion to leftward optokinetic stimulus.

Less than 2 weeks after her first visit, the patient was able to return to her university and resume her studies with no apparent residual effects. She had no more difficulty exercising, going shopping, thinking, reading, studying, or going downstairs. Her TMJ symptoms had also resolved. The patient was contacted at 1 month and at 6 months following her last visit and was doing well at each interval.

Discussion

Brain plasticity is the process by which synapses adapt in response to activation brought about by changes in the internal or external milieu. Synapses that receive adequate stimulation will become stronger and more efficient. Those synapses that do not receive adequate stimulation will become weak and less efficient, and they may eventually be eliminated. Brain plasticity is the process by which the brain can potentially compensate for lesions, such as those caused by mTBI.¹⁵ The history, physical exam, and VNG studies in this patient’s case helped to determine which of her neural pathways were most in need of activation. Specific therapeutic interventions were applied to promote brain plasticity in the areas that proved to be deficient.

Although the TMJ portion of the patient’s symptom complex was treated locally, the patient’s other signs and symptoms were treated with interventions designed to stimulate particular aspects of the central nervous system. The history and the physical exam findings indicated that the left hemisphere of the cerebral cortex was more affected by the patient’s head trauma than the right side. Activation of a particular cerebral hemisphere is greater with manipulation of contralateral spinal and extraspinal joints compared to manipulation of articulations on the ipsilateral side.^16,17 Manual high velocity, low amplitude adjustments were therefore administered to fixated right-sided spinal and extraspinal joints. Complex movements of the right upper and lower extremities were also used to enhance activation of the right cerebellum and left cerebral cortex.¹⁸

VNG is a computerized device that is primarily used in vestibular assessment. It consists of the use of infrared goggles to trace and measure eye movements during visual stimulation and positional changes. A set of standardized tasks is given to the patient with instructions to use the eyes to follow a target that is generated on a video monitor. A course of testing usually includes evaluating smooth tracking (pursuits), saccades, and optokinetic responses, as well as detecting nystagmus with and without fixation. The infrared goggles can also be used to observe for the existence or absence of vestibulo-ocular reflexes (VORs) and whether or not those reflexes can be attenuated by fixation. Although VNG is used commonly in vestibular assessment, the information provided by this technology may also be of value in evaluating and managing mTBI as dysfunctional eye movements are typically found after concussion.¹⁹ This case is an illustrative example of a patient who did not have outright vestibular complaints postconcussion and yet was able to benefit from a unique application of VNG. Whereas the history and physical exam were very helpful in determining the broad strokes of the source of this patient’s complaints, the VNG provided very specific details about which eye movements were dysfunctional and likely contributing to her symptom complex.

Both the physical and VNG exam revealed that many reflexive eye movements were dysfunctional in this patient, including the r-VORs and optokinetic reflexes. These eye movements may be observed by physical examination or with VNG, although VNG allows the practitioner to record and trace the movements for more detailed observation.

An r-VOR generates eye movements to compensate for brief angular head movements for the eyes to stay fixed on a target. The r-VOR is characterized by slow phases of eye movements opposite the side of head rotation and fast phases toward the side of head rotation.²⁰

Optokinetic responses are generated by visual stimuli to the central vestibular system and are similarly characterized by slow and fast phases of eye movement, with slow phases in the direction of the optokinetic stimulus and fast phases in the opposite direction. This is referred to as optokinetic nystagmus. If the fast phase of the nystagmus is generated to the right side, the nystagmus is referred to as right-beating.^21,22 Warm caloric stimulus (air or water) will also produce a pattern of alternating slow and fast phases of eye movements, with the slow phase being away from the side of stimulus and the fast phase moving toward the side of stimulus.²³

Therapeutic interventions of gentle, left rotational head thrusts immediately followed by optokinetic stimulus were initially employed to promote activation of the left saccadic generators and stimulate the types of eye movements seen with a functioning right r-VOR.^24,25 This intervention was applied for only the first 2 days as follow-up infrared oculography revealed that the right r-VOR was by then functioning normally. Right warm air caloric stimulus was provided to cause the type of right-beating nystagmus that is analogous to what is seen with a right r-VOR.²⁶ This was applied during the second week of care to build more plasticity in the right r-VOR system.

This case report had limitations in that it would have been ideal for a baseline VNG to have been performed prior to her mTBI so as to compare her eye movements before and after injury. Because the bulk of her symptoms began after she sustained the recent concussion and her eye movements showed improvement as her symptoms receded, we are making the assumption that she had essentially normal eye movements prior to her head trauma.

Conclusion

VNG is helpful in evaluating VORs, gaze stability, pursuits, saccades, and optokinetic reflexes that may be aberrant postconcussion. VNG is a useful tool in measuring the effectiveness of therapeutic interventions in mTBI through pre- and postassessments. This case suggests that chiropractic and chiropractic functional neurological applications specifically applied can rapidly improve outcomes in mTBI syndrome as demonstrated by VNG assessment.

Figure 1.

Rightward OPK stimulus

Figure 2.

Upward Optokinetic Stimulus

Figure 3.

Downward Optokinetic Stimulus

Figure 4.

Spontaneous Nystagmus Without Fixation

Figure 5.

Vertical Pursuits (0.1 Hz)

Figure 6.

Vertical Pursuits (0.2 Hz)

Figure 7.

Vertical Pursuits (0.4 Hz)

Biographies

Laura A. Swingen, DC, DACNB; is a board-certified chiropractic neurologist practicing in Portland, OR.

Rosi Goldsmith, LMT; is a massage therapist practicing in Portland, OR.

Judith Boothby, MS, DC; is a chiropractic physician practicing in Portland, OR.

Terry McDermott, DC; is a chiropractic physician practicing in Portland, OR.

Catherine Kleibel, BA; is a research assistant in Portland, OR