By Marcello Cherchi, MD PhD
For patients
Some people have a tendency to feel disoriented when driving, particularly on a highway, or in a wide-open area. This is sometimes called motorist disorientation syndrome (MDS). The cause of MDS is unknown. Some patients notice improvement with vision therapy (usually offered by a neuro-optometrist). Other patients notice some improvement with treatments otherwise used for migraine.
For clinicians
Overview
Motorist disorientation syndrome (MDS) is a condition that tends to occur to drivers (less commonly to passengers) in automobiles. The incidence and prevalence are unknown. Its pathophysiology is unknown, though at some level it is probably the result of the sensory mismatches that occur in this situation of passive motion. People appear more vulnerable to this problem when they are driving a vehicle at a higher speed in an environment with fewer (or with distant) visual cues, such as during highway travel. Other predisposing situations include driving along curves or over hills. Vision therapy exercises (usually administered under the supervision of neuro-optometry) seem more successful than vestibular therapy. Pharmacologic strategies have not been well-studied, but case series report some success with agents otherwise used for migraine prophylaxis. Prognosis is uncertain.
Introduction
Ainsworth and colleagues comment that, “The term ‘motorist’s vestibular disorientation syndrome’ was coined for… situation specific dizziness” of “patients who primarily experienced symptoms of dizziness/disorientation while in a motor car” (Ainsworth et al. 2023). Bronstein and Golding (Bronstein et al. 2013) suggest that the term “motorist’s disorientation syndrome” (MDS) is more appropriate.
Some literature classifies motorist’s disorientation syndrome (MDS) as a type of visual vertigo (Bronstein 1995).
Epidemiology
The incidence and prevalence of MDS is unknown. Bronstein and Golding comment that:
“The number of disoriented motorists reported is too small to draw firm conclusions about epidemiology. Approximately 1% of patients referred to a well-established, London clinic specializing in vestibular and balance disorders” (Bronstein et al. 2013).
Gresty and Ohlman state, “Each year in the neuro-otological clinic with which one of the authors (MG) is associated an average of 10 patients out of 200 seen as outpatients present with primary MDS” (Gresty and Ohlmann 2002), suggesting 5% of vestibular outpatients in that practice.
A case series (Ainsworth et al. 2023) of 18 patients (9 female, 9 male) reported that the mean age of onset was 41.7 years (standard deviation of 10 years, range 20 – 56 years). In men the mean duration was 3.89 years (standard deviation 1.97 years, range 1 – 7 years). In women the mean duration was 8.89 (standard deviation 5.26, range 2 – 17 years).
Pathophysiological mechanism of disease
In a general sense, motorist disorientation syndrome is related to several other disorders (such as motion sickness and cybersickness) in which discrepancies (mismatches) between different sensory inputs results in the failure of multisensory integration.
Some investigators postulate that MDS results from over-reliance on visual cues (also called visual dependence). Such over-reliance on the visual system is partly a result of the fact that “the force-motion environment is potentially ambiguous” (Gresty and Ohlmann 2002). As an example of this, consider that:
- For an earth-stationary individual oriented in a backwards-leaning position, the vector of linear acceleration (from the perspective of that individual) points infero-posteriorly, and is the result of gravity alone.
- For an individual oriented upright (earth vertical) in a human centrifuge facing the center of the centrifuge while being rotated by the centrifuge, the vector of linear acceleration (from the perspective of that individual) points infero-posteriorly, and is the result of a combination of gravity and centrifugal force.
In both of these circumstances there is a vector of linear acceleration pointing infero-posteriorly (from the perspective of that individual), and will stimulate the vestibular system identically. If visual cues are available, then the visual information can help disambiguate these situations. The two situations will be difficult to disambiguate if vision is distorted, and impossible to disambiguate if vision is entirely unavailable.
In their original description of MDS, Page and Gresty comment that:
“False perception of the motions of the self and/or external objects in the physical world may be provoked by… unusual conditions of motion and environmental structure… [in which] the sensory inputs which are normally combined to provide an accurate model of the physical world provide false information because either the stimuli are unphysiological or important sensory information is lacking or distorted” (Page and Gresty 1985).
They observe that:
“Motorway driving conditions are particularly conducive to the development of these symptoms; visual background detail is at a minimum and with the eyes looking straight ahead the ‘optic flow field’ which moves in a series of parallel straight lines towards the driver is a weak stimulus for visual self-stabilisation… Conversely in town, buildings, trees and traffic provide a rich visual background with plentiful references to the true vertical, and there are continual angular and linear changes in the motion of the traffic” (Page and Gresty 1985).
They suggest:
“A theoretical explanation can be proposed to account for the illusions of turning, tilt or the feeling of being pushed sideways. Of first consideration, driving a car involves unusual visual and motion stimuli which do not occur in normal activities. Much of the vestibular stimulation involved in driving is of low frequency content and out of the normal physiological range of the labyrinth. Hence vision, both peripheral and central, is of overriding importance, not only for steering but also for assessing changes in speed, and this dominance of vision obviates problems which arise from a disordered vestibular system. The vestibular system becomes more important in circumstances when vision is reduced as when driving in an empty landscape. Hence, spatial disorientation in an empty visual field is likely to be a consequence of abnormal vestibular signals, or erroneous central interpretation of vestibular information” (Page and Gresty 1985).
Bronstein and Golding (Bronstein et al. 2013) speculate on the maladaptive sensory integration that might lead to MDS:
“Motorists learn to interpret sensory stimuli in the context of the car stabilized by its suspension and guided by steering. However, the sensory stimulation during driving is potentially ambiguous: The forces of cornering may be interpreted as tilt rather than as lateral acceleration and visual flow of the road and traffic can be interpreted to indicate veering, a form of visual vertigo. In motorists’ disorientation, certain individuals appear to develop a heightened awareness of these false perceptions of car orientation, readily experiencing stereotypical symptoms of threatened rolling over on corners and veering on open highways or in streaming traffic” (Bronstein et al. 2013).
Clinical presentation
Gresty and Ohlmann (Gresty and Ohlmann 2002) cite the following as among the most common experiences described by patients with MDS:
- “The car feels as if it veers on wide open roads such as motorways.”
- “The car feels that is turning into vehicles being overtaking.”
- “The car feels that it is about to turn over when descending and rounding a bend.”
The case series of 18 patients described by Ainsworth and colleagues (Ainsworth et al. 2023) reported that:
- 13 patients (72%) experienced a “unidirectional sense of pulling.”
- 13 patients (72%) “only experienced symptoms on roads with high speed limits.”
- 12 patients (67%) described symptom onset as acute.
- 11 patients (61%) “also reported symptoms whilst being a passenger.”
- 8 patients (44%) “also experienced these symptoms when not in a car.”
- 7 patients (39%) “reported feelings of acute anxiety or panic associated with their [vestibular] symptoms.”
- 6 patients (33%) “reported that their symptoms were worse on bumps/hills.”
Furthermore:
- 17 patients (94%) “change[d] their driving habits.”
- 11 patients (61%) “stopped driving on provoking roads.”
- 6 patients (33%) “stopped driving completely.”
Physical examination
In a patient with MDS who is otherwise healthy, physical examination should be normal.
Ocular motor examination
Pawar and colleagues (Pawar et al. 2023) reported the following ocular motor findings in 17 patients:
|
Normal |
Abnormal |
|
|
Horizontal saccades |
Normal in 17 (100%) |
— |
|
Vertical saccades |
Normal in 15 (88%) |
Hypometric in 2 (12%) |
|
Horizontal smooth pursuit |
Normal in 13 (77%) |
Saccadic in 4 (24%) |
|
Vertical smooth pursuit |
Normal in 1 (6%) |
Saccadic in 16 (94%) |
|
Spontaneous nystagmus |
Normal (absent) in 14 (82%) |
Up beat nystagmus in 3 (18%) |
|
Head-shaking nystagmus |
Normal (absent) in 14 (82%) |
Present in 3 (18%) |
|
Hyperventilation-induced nystagmus |
Normal (absent) in 14 (82%) |
Present in 3 (18%) |
Testing: vestibular
In the case series of Ainsworth and colleagues (Ainsworth et al. 2023), of the 15 patients who had “complete vestibular testing” (which included ocular motor testing, caloric testing, slow harmonic acceleration, step velocity testing, visual vestibulo-ocular reflex suppression, optokinetic nystagmus, optokinetic after-nystagmus), nine (60%) had at least one abnormal test reflecting vestibular asymmetry.
Differential diagnosis
Migrainous hypersensitivity to motion, and persistent postural perceptual dizziness are on the differential diagnosis.
Treatment
In the case series of 18 patients studied by Ainsworth and colleagues (Ainsworth et al. 2023):
- 8 patients (44%) received vestibular rehabilitation. Of those 8 patients, “5 were treated with traditional vestibular rehabilitation gaze stabilisation alone, 4 of whom found that these didn’t help, and 1 found them subjectively useful.”
- 3 patients (17%) “were treated with a combination of visual vertigo and gaze stabilisation exercises. All of these found the gaze stabilisation exercises not useful but the visual vertigo exercises useful.”
Their series also “showed that there was a significant difference between the age of the patient and whether the treatment helped… with treatment more likely to help those who are younger” (Ainsworth et al. 2023).
There are no controlled trials of pharmacotherapy for MDS. Pawar and colleagues (Pawar et al. 2023) studied a series of 24 patients, and reported some (albeit inconsistent) response to agents that are also used as migraine prophylactics, such as:
- Beta blockers (bisoprolol)
- GABA-ergic medications (gabapentin, pregabalin)
- Tricyclic compounds (amitriptyline)
- Serotonin-norepinephrine reuptake inhibitors (venlafaxine, desvenlafaxine)
- Magnesium
Prognosis
The literature offers little regarding prognosis, which appears quite variable. Pawar and colleagues comment that, “The natural history of motorist vestibular disorientation syndrome ranges from complete recovery with or without treatment to chronic suffering without relief” (Pawar et al. 2023).
References
Ainsworth C, Davies R, Colvin I, Murdin L (2023) Motorist disorientation syndrome; clinical features and vestibular findings. J Vestib Res 33: 339-348. doi: 10.3233/VES-220088
Bronstein AM (1995) The visual vertigo syndrome. Acta Otolaryngol Suppl 520 Pt 1: 45-8.
Bronstein AM, Golding JF, Gresty MA (2013) Vertigo and dizziness from environmental motion: visual vertigo, motion sickness, and drivers’ disorientation. Semin Neurol 33: 219-30. doi: 10.1055/s-0033-1354602
Gresty MA, Ohlmann T Motorist Vestibular Disorientation Syndrome Revisited RTO-HFM [Research and Technology Organization – Human Factors and Medicine Panel] Symposium on “Spatial Disorientation in Military Vehicles: Causes, consequences and Cures”, La Coruña, Spain 2002. RTO-MP-086
Page NG, Gresty MA (1985) Motorist’s vestibular disorientation syndrome. J Neurol Neurosurg Psychiatry 48: 729-35. doi: 10.1136/jnnp.48.8.729
Pawar V, Ashraf H, Dorsala S, Mary P, Hameed N, H DN, Adatia SP, Raj L, Ananthu VR, Shouka M (2023) Motorist’s Vestibular Disorientation Syndrome (MVDS)-Proposed Diagnostic Criteria. J Pers Med 13. doi: 10.3390/jpm13050732
