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In the UK, having Multiple Sclerosis (MS) is a notifiable condition, where the person must notify the DVLA. Patients with MS (pwMS) may drive as long as safe vehicle control is maintained at all times and licence valid for 1, 2 or 5 years may be issued following medical enquires by DVLA. The licence may specify a restriction to cars with certain controls.
It should be noted that the guidance on MS might appear differently in other countries. In the EU Driving Licence Directive MS would be included in the Neurological Section of the Fitness to Drive criteria.
As symptoms can vary hugely between pwMS and can also evolve over time in a single person, it is advisable that the specific symptoms presented be checked against local legislative frameworks for driving.
(Ghasemi, Razavi and Nikzad, 2017; McGinley, Goldschmidt and Rae-Grant, 2021)
MS is an autoimmune disorder of the central nervous system (brain and spinal cord) that is characterised by demyelination (i.e., damage to the insulating sheathes of the nerves). This tends to be chronic and typically progressive in nature, and can present in a wide spectrum of clinical symptoms including, but not limited to:
These clinical symptoms can present in isolation but also co-exist in a single patient.
MS generally initially presents in younger adults at the age of 20-40 years, with about 2-10% presenting after 50 years.
The cause of MS is thought to be multifactorial with both environmental factors and genetic predispositions implicated. Of note, the incidence of MS is higher in countries with higher geographical latitudes. For example, in Scotland, the incidence rate of MS in 2021 is 10.6 per 100,000 of population (Public Health Scotland, 2022).
MS is categorised into three sub-types:
RRMS is the most common subtype affecting about 85% of all pwMS and is characterised by a disease course unpredictable acute flare-ups of neurological symptoms followed by periods of remission. About 50% of patients with RRMS will go on to develop SPMS, which is characterised by progressive disability without any acute flare-ups. PPMS affects about 15% of all pwMS and is characterised by progressive neurological symptoms from the onset but can be considered to be either active or non-active.
Depending on the MS sub-type and the frequency of relapses, pwMS may be treated with a wide repertoire of Disease Modifying Therapies (DMTs), which all aim to modulate the individual’s immune system with the aim to reduce the frequency of relapses. For the acute relapses itself, this is usually treated with steroids. At present, most of the DMTs are targeted towards RRMS, with very limited treatment options for pwMS in the progressive phase of disease. The management of associated impairments or issues in these patients is usually symptomatic.
A common term that is useful to understand is that of the Expanded Disability Status Scale (EDSS)(Kurtzke, 1983). This is essentially a way of measuring the degree of neurological impairment or disability in a pwMS in an ordinal scale from 0 to 10, with higher ratings corresponding to more severe disability. The EDSS is usually used to categorise pwMS in clinical trials and other studies. However, it should be noted that a person’s EDSS scale may not be relevant to their driving ability so should be used in association with an assessment.
The National MS Society in the USA has a good online resource for professionals, especially an overview on the symptoms of MS: https://www.nationalmssociety.org/For-Professionals/Clinical-Care/Resources-for-You-and-Your-Practice/Publications
The MS Society in the UK has helpful information in relation to driving designed for pwMS: https://www.mssociety.org.uk/care-and-support/everyday-living/getting-around/driving-and-dvla
There is a paucity of consistent evidence in literature to make a definite judgement on the prognosis of MS on driving, hence the diagnosis itself is not considered as a definite contra indication for driving. A recent narrative review highlighted that about 20% of pwMS might not be able to drive safely. There was no strong association between driving ability and age and physical disability, although it is to be noted that the patient cohorts are generally younger, with a mean age from 36 to 55 years, and demonstrated low to moderate disability (Seddiq Zai et al., 2022) .
The natural history of MS in itself is highly variable within the individual and will also depend on the type of MS. Approximately 20-65% of patients with RRMS will transition to SPMS, with a median time to conversion to SPMS from initial diagnosis at 15 years in untreated RRMS. In older cohort studies predating the current repertoire of DMTs, the median from diagnosis to requiring a walking aid in RRMS and PPMs were reported to be 20 and 7 years respectively (Ghasemi, Razavi and Nikzad, 2017; McGinley, Goldschmidt and Rae-Grant, 2021) .
If a pwMS has been diagnosed with the progressive course of the disease, then progression of symptoms and the resultant accumulation of various MS-related impairments (physical, cognitive, psychological and visual) will likely have an overall negative impact on driving ability. Therefore, the timings between review assessments may need to be monitored and it might be possible that the duration of Driving Licence entitlement can be adjusted based on disease progression.
In addition to the wide spectrum of associated physical and cognitive impairments that can occur in pwMS which require careful assessment in relation to driving, another important factor to consider is in relation to the frequency and nature of relapses, typically in patients with RRMS.
It is difficult to predict the frequency of relapses in RRMS, as this is influenced by both individual circumstances and also DMTs used. Moreover, symptoms associated with the relapse may or may not recover completely following the exacerbation.
It is generally unsafe to drive during a MS relapse. Symptoms should be monitored closely, with either driving to resume if there is complete resolution of the symptom, or for a formal medical assessment of fitness to drive if symptoms persist.
Implications of Co-morbidities (Magyari and Sorensen, 2020)
There are certain diseases that co-exist with MS in a higher proportion when compared to the general population, and additional assessments need to be considered in the context of driving where appropriate. Of particular note, there is an association between MS and Type I Diabetes Mellitus (T1DM), with some studies suggesting a 3-fold-high incidence rate of MS in patients with T1DM. This is particularly relevant to driving assessment where due consideration needs to be made in relation to vision, sensory deficits, and also Hypo glycaemic (low blood sugar) awareness.
Other autoimmune conditions associated with MS but with less implications for driving include thyroid disorders, inflammatory bowel disease and psoriasis. There is also a higher prevalence of vascular co-morbidities in pwMS, including hypertension, ischaemic heart disease and hyperlipidaemia, and resultant increased risk of macrovascular complications such as acute coronary syndromes and
cerebrovascular disease.
Other relevant co-morbidities include depression, anxiety, back pain, migraine and sleep disorders (e.g., sleep-related breathing disorders, insomnia and restless legs syndrome).
There is a paucity of consistent evidence in literature to make a definite judgement on the prognosis of MS on driving, hence the diagnosis itself is not considered as a definite contra indication for driving. A recent narrative review highlighted that about 20% of pwMS might not be able to drive safely. There was no strong association between driving ability and age and physical disability, although it is to be noted that the patient cohorts are generally younger, with a mean age from 36 to 55 years, and demonstrated low to moderate disability (Seddiq Zai et al., 2022).
The natural history of MS in itself is highly variable within the individual and will also depend on the type of MS. Approximately 20-65% of patients with RRMS will transition to SPMS, with a median time to conversion to SPMS from initial diagnosis at 15 years in untreated RRMS. In older cohort studies predating the current repertoire of DMTs, the median from diagnosis to requiring a walking aid in RRMS and PPMs were reported to be 20 and 7 years respectively (Ghasemi, Razavi and Nikzad, 2017; McGinley, Goldschmidt and Rae-Grant, 2021).
If a pwMS has been diagnosed with the progressive course of the disease, then progression of symptoms and the resultant accumulation of various MS-related impairments (physical, cognitive, psychological and visual) will likely have an overall negative impact on driving ability. Therefore, the timings between review assessments may need to be monitored and it might be possible that the duration of Driving Licence entitlement can be adjusted based on disease progression.
In addition to the wide spectrum of associated physical and cognitive impairments that can occur in pwMS which require careful assessment in relation to driving, another important factor to consider is in relation to the frequency and nature of relapses, typically in patients with RRMS.
It is difficult to predict the frequency of relapses in RRMS, as this is influenced by both individual circumstances and also DMTs used. Moreover, symptoms associated with the relapse may or may not recover completely following the exacerbation.
It is generally unsafe to drive during a MS relapse. Symptoms should be monitored closely, with either driving to resume if there is complete resolution of the symptom, or for a formal medical assessment of fitness to drive if symptoms persist.
There are certain diseases that co-exist with MS in a higher proportion when compared to the general population, and additional assessments need to be considered in the context of driving where appropriate.
Of particular note, there is an association between MS and Type I Diabetes Mellitus (T1DM), with some studies suggesting a 3-fold-high incidence rate of MS in patients with T1DM. This is particularly relevant to driving assessment where due consideration needs to be made in relation to vision, sensory deficits, and also Hypo glycaemic (low blood sugar) awareness.
Other autoimmune conditions associated with MS but with less implications for driving include thyroid disorders, inflammatory bowel disease and psoriasis.
There is also a higher prevalence of vascular co-morbidities in pwMS, including hypertension, ischaemic heart disease and hyperlipidaemia, and resultant increased risk of macrovascular complications such as acute coronary syndromes and cerebrovascular disease.
Other relevant co-morbidities include depression, anxiety, back pain, migraine and sleep disorders (e.g., sleep-related breathing disorders, insomnia and restless legs syndrome).
There are numerous physical impairments that can be present in MS. In relation to driving, the following physical issues are considered briefly:
1. Weakness
Weakness is one of the most common physical impairments in MS and can affect pwMS in multiple ways. This most typically affects the limbs either in isolation (e.g., foot drop) or in combination, and there is no fixed pattern across different patients. However, a pwMS presenting lesions in the spinal cord can sometimes present as a paraplegic.
This weakness is usually progressive in nature and does get worse over time. In advanced disease, weakness can become generalised, affecting trunk and neck control. Bulbar muscles can also be affected, impacting on both speech and swallow.
This weakness is usually progressive in nature and does get worse over time. In advanced disease, weakness can become generalised, affecting trunk and neck control. Bulbar muscles can also be affected, impacting on both speech and swallow.
2. Sensory disturbance
Sensory disturbance is another very common symptom in MS. This can manifest in various ways but generally either with positive or negative symptoms.
Positive symptoms involve an altered sensory perception and can present as paraesthesia (i.e., tingling, burning or prickling), hypersensitivity and neuropathic pain.
Negative symptoms involve a reduction or loss of sensory perception and can present as numbness, loss of sensory modalities (e.g., pain perception, temperature perception) and proprioceptive loss (i.e., reduced awareness of body position in space).
3. Spasticity
Spasticity is common in MS and usually co-exists with weakness. This is a sensorimotor phenomenon only present in disorders affecting the brain and spine, which presents as an abnormal involuntary activation of muscle tone and can either be sustained or intermittent in nature (Burridge et al., 2005). This can cause postural abnormalities with restricted range of movement, pain and spasms. Of note, spasms generally can present in either flexor or extensor patterns (i.e., where all relevant body parts bend or straighten respectively).
For some pwMS suffering from spasticity, spasms can sometimes be triggered on the road when going over bumps.
4. Tremors
Tremors can be a common presentation in pwMS. This is usually due to MS lesions in the cerebellar region of the brain that control coordination, presenting most of the time as an intention tremor (i.e. involuntary tremor during intentional movement). This usually affects the upper limbs and speech muscles.
Other types of tremors include tremors at rest and postural tremor (i.e. involuntary tremor when holding a position against gravity), and again these commonly affect the upper limbs but can also affect the head and neck.
In some cases, there may be a combination of the above-described tremors in what is called a Holmes or rubral tremor.
5. Dizziness
Dizziness is a common symptom in MS. This can either present as light-headedness or vertigo, and relates to MS lesions in the brainstem, cerebellum or inner ear. Vertigo can be episodic in nature and takes days to resolve with or without medication. Dizziness can affect balance and be debilitating in severe cases.
6. Seizures
There is an association between MS and seizures with a higher incidence of seizures reported in pwMS compared to the general population. The prevalence of seizures in pwMS is estimated to be about 2% (Mirmosayyeb et al., 2021).
National legislation should always be checked as in some countries a pwMS diagnosis may mean an automatic unfit to drive ruling.
There are 3 main visual issues that can present in a pwMS:
1. Optic neuritis
Optic neuritis is the inflammation of the optic nerve that usually results in pain in the affected eye, typically with eye movement, and also temporary loss of vision in that eye. This is a common symptom of a MS relapse and usually presents unilaterally. Other symptoms of optic neuritis can include visual field loss, loss of colour vision and also flashing/flickering lights.
Most pwMS who have a single episode of optic neuritis will eventually recover their vision.
2. Diplopia
Another common symptom of MS is binocular diplopia, although this can be persistent, and tends to worsen with fatigue. This is usually a result of damage to the cranial nerves supplying the various extraocular muscles, subsequently leading to the eyes being out of alignment from one another, especially during eye movement. Diplopia is typically horizontal or vertical and can occur at rest.
A pathognomonic visual symptom of MS is internuclear ophthalmoplegia (INO) where there is the inability to perform conjugate horizontal gaze (i.e. inability to move both eyes in unison in the horizontal plane) due to damage of the specific nerve that links the nerve bodies of the 2 cranial nerves involved in conjugate horizontal gaze. This clinically manifests with the eye on the affected side not being able to adduct past the midline, with the eye on the unaffected side abducting with associated nystagmus. INO can also occur bilaterally.
3. Nystagmus
Nystagmus (i.e. rhythmical, repetitive and involuntary movement of the eyes, seen as trembling) is fairly common in pwMS. This can be horizontal, vertical and rotary in nature, and a manifestation of either issues involving the optic nerve itself, or the cerebellum, which is the main centre in the brain for coordination of movement and balance.
While nystagmus itself can by asymptomatic, it can also lead to debilitating symptoms of dizziness and/or vertigo, oscillopsia (i.e. perception that external environment is moving), blurred vision and abnormal head positioning.
For a pwMS, a visual assessment for visual acuity, visual field, and diplopia needs to be carried out as routine regardless of reported symptoms, to ensure that they fulfill the minimal standards for driving under local legislative frameworks.
If any concerns are raised during assessment (e.g. uncorrected diplopia), advice should be given for a more in-depth assessment by a competent medical expert.
(DeLuca et al., 2015; Amato et al., 2018; Kalb et al., 2018; Higueras et al., 2022)
Cognitive impairment is a common symptom in MS, irrespective of subtype, and can be present in 40-70% of pwMS. However, this can be more frequent and severe in progressive forms of MS.
Cognitive impairment in pwMS is usually progressive in nature with gradual deterioration over time, although MS relapses in RRMS involving acute deterioration in cognitive function can also happen but with potential for recovery.
Common cognitive domains affected in MS include processing speed (usually the first to be identified), memory, verbal fluency, executive function and visuospatial or visuoperceptual function. In relation to executive function and associated frontal lobe impairments, deficits in cognitive flexibility, inhibition and abstraction can also be present.
There is no one cognitive screening tool that will be able to evaluate all the cognitive domains that may be affected in pwMS.
The gold standard to evaluate all cognitive domains and mood in pwMS still remains a comprehensive neuropsychological assessment. It should be noted that not all cognitive domains are equally important for driving, hence an assessment targeted at fitness to drive might be required.International consensus based on the best available evidence on the cognitive assessment in MS recommends early baseline screening with the Symbol Digit Modalities Test (SDMT) or similarly validated test, as minimum (Amato et al., 2018; Kalb et al., 2018; Higueras et al., 2022). The SDMT measures sustained attention, processing speed, visual scanning, and motor speed.
Other screening tests routinely used in pwMS include:
In the context of driving assessment, a number of other cognitive screening tools have also been used, including the Stroke driver screening assessment (SDSA) and the Useful field of view (UFOV) assessment, which have been found to have a degree of predictability on driving performance. However, it is important to note that these are not validated predictive test batteries for driving ability and fitness to drive will still need to be assessed through multiple modalities including on-road assessments (Seddiq Zai et al., 2022).
Sativex
Sativex is a cannabis-based medication that is licensed for the management of intractable spasticity in pwMS, and it is not uncommon to come across this during driving assessment.
In the UK, anyone found with certain drugs in their body while driving can be prosecuted, whether their driving is impaired or not. If a pwMS is taking Sativex as prescribed by their MS specialist and driving is not impaired, they might be able to claim a ‘medical defence’ if they test positive for cannabis. But as local legislative frameworks may differ in different countries, this should always be checked.
Sativex itself has been shown not to necessarily impair driving performance and may perhaps even improve driving ability in a small and selected group of pwMS (Freidel et al., 2015; Celius and Vila, 2018).
Depending on a person’s motor and sensory disabilities, vehicle adaptations might be advised. If the latter predominantly involve lower limbs, hand operated adaptations could be advised. If those disabilities are lateralised, automated gearshift or an accelerator pedal on the left could be advised. Vehicle adaptations will always be determined by the locomotor and sensory deficits.
What to expect of a pwMS for an on-road driving assessment will depend on what clinical features they present with.
As per regular practice, the patient will need to fulfill the visual requirements and all other pure medical requirements for example epilepsy or diabetes for driving before being allowed for an on-road assessment.
In those presenting primarily with physical impairments with no cognitive issue, they will need to get assessed on road with the relevant vehicular adaptations. There should not be too much concern with the judgement aspects of driving apart from getting used to handling the vehicular adaptation.
In those with cognitive impairments, extra care needs to be taken during on-road assessment as judgement may be impaired depending on cognitive domain affected (e.g. reduced divided attention, impulsivity, slowed processing).
Specifically, indicators for failing the on-road assessment in pwMS have been found to include (Seddiq Zai et al., 2022):
In a small minority of pwMS who are younger, it may be the case that a patient is attending for driving assessment as a first-time driver. Adjustments may need to be made for an on-road assessment in a quieter area, as this will effectively be the first driving lesson.
This will again largely depend on the presenting clinical features in a pwMS. In principle, physical impairments can be overcome more easily to maintain function; whereas in cognitive impairment, once present, it is more challenging to adjust to, especially in driving where judgement and speed of reaction are paramount.
Adjustments to the following physical impairments presenting in MS are briefly discussed:
1. Weakness
There is no real therapeutic option in MS aimed at improving weakness. The only medication that has been found to improve walking speed in some pwMS is Fampridine. It is unclear at this stage if Fampridine has any impact on driving ability. As far as adaptations are concerned for compensating muscular weakness, extra enforcement on steering and pedals could be envisaged.
In pwMS presenting with foot drop, this is usually managed with orthotic devices such as an AFO splint or in some cases, a functional electrical stimulation (FES) device. A foot drop and its current adaptations are generally not safe for driving due to challenges with managing pedals. Even with a FES device, it is mainly designed to improve ankle dorsiflexion at heel strike during walking and will not improve ankle activity in the context of driving. Vehicular adaptations are generally advised in this instance.
2. Spasticity
A reduction in spasticity has the potential to improve function and is relevant to both upper and lower limb physical function. In addition to oral medications, Botulinum toxin injections are also used in the treatment of focal spasticity, with the treatment interval in pwMS typically being 4-6 months (i.e. benefit wearing off at the end of treatment interval). Some pwMS presenting with regional spasticity (i.e. below the waist) may also be managed with an intrathecal baclofen pump.
The use of a Mollii suit may be mentioned by some pwMS, although this is something very new in the area of neuromodulation. It is essentially jacket and trousers that is designed to deliver therapeutic electrical stimulation to manage spasticity. There is still not much literature around its use in MS as of early 2023.
3. Tremors
In addition to oral medications and some conservative options (e.g. weighted cuffs), which normally have fairly limited benefit on tremor management, some pwMS may have been given the treatment option for Deep Brain Stimulation (DBS). This involves the neurosurgical placement of a neurostimulator which sends electrical impulses through implanted electrodes to specific areas of the brain which aim to reduce the tremors. The DBS device can be turned off and on, and also adjusted through a handheld controller by the patient.
4. Diplopia
Some pwMS presenting with diplopia will have this managed in various ways. An occlusion patch is sometimes used, and, in this instance, monocular vision will need to be assessed in the context of driving. In some countries like the UK, the DVLA would need to authorise such an assessment from a qualified expert. Other patients will be managed via prism lenses which aim to compensate for eye muscle weakness by bending light in a way which ensures the alignment of vision from both eyes. Botulinum toxin injections into the eye muscles may also be used in some pwMS for the treatment of diplopia, and the treatment interval and associated wearing off of benefit needs to be considered.
Amato, M. P. et al. (2018) ‘Cognitive assessment in multiple sclerosis-an Italian consensus.’, Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology, 39(8), pp. 1317–1324. doi: 10.1007/s10072-018-3427-x.
Burridge, J. H. et al. (2005) ‘Theoretical and methodological considerations in the measurement of spasticity.’, Disability and rehabilitation, 27(1–2), pp. 69–80.
Celius, E. G. and Vila, C. (2018) ‘The influence of THC:CBD oromucosal spray on driving ability in patients with multiple sclerosis-related spasticity.’, Brain and behavior, 8(5), p. e00962. doi: 10.1002/brb3.962.
DeLuca, G. C. et al. (2015) ‘Cognitive impairment in multiple sclerosis: clinical, radiologic and pathologic insights.’, Brain pathology (Zurich, Switzerland), 25(1), pp. 79–98. doi: 10.1111/bpa.12220.
Freidel, M. et al. (2015) ‘Drug-resistant MS spasticity treatment with Sativex(®) add-on and driving ability.’, Acta neurologica Scandinavica, 131(1), pp. 9–16. doi: 10.1111/ane.12287.
Ghasemi, N., Razavi, S. and Nikzad, E. (2017) ‘Multiple Sclerosis: Pathogenesis, Symptoms, Diagnoses and Cell-Based Therapy.’, Cell journal, 19(1), pp. 1–10. doi: 10.22074/cellj.2016.4867.
Higueras, Y. et al. (2022) ‘Cognitive assessment in patients with multiple sclerosis: A Spanish consensus.’, Frontiers in rehabilitation sciences, 3, p. 1006699. doi: 10.3389/fresc.2022.1006699.
Kalb, R. et al. (2018) ‘Recommendations for cognitive screening and management in multiple sclerosis care.’, Multiple sclerosis (Houndmills, Basingstoke, England), 24(13), pp. 1665–1680. doi: 10.1177/1352458518803785.
Kurtzke, J. F. (1983) ‘Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS).’, Neurology, 33(11), pp. 1444–1452. doi: 10.1212/wnl.33.11.1444.
Magyari, M. and Sorensen, P. S. (2020) ‘Comorbidity in Multiple Sclerosis ’, Frontiers in Neurology . Available at: https://www.frontiersin.org/articles/10.3389/fneur.2020.00851.
McGinley, M. P., Goldschmidt, C. H. and Rae-Grant, A. D. (2021) ‘Diagnosis and Treatment of Multiple Sclerosis: A Review’, JAMA, 325(8), pp. 765–779. doi: 10.1001/jama.2020.26858.
Mirmosayyeb, O. et al. (2021) ‘Prevalence of Seizure/Epilepsy in Patients with Multiple Sclerosis: A Systematic Review and Meta-Analysis.’, International journal of preventive medicine, 12, p. 14. doi: 10.4103/ijpvm.IJPVM_75_20.
Public Health Scotland (2022) Scottish Multiple Sclerosis Register National Report 2022. Available at: https://publichealthscotland.scot/media/14198/annual-report.pdf.
Seddiq Zai, S. et al. (2022) ‘Driving ability and predictors for driving performance in Multiple Sclerosis: A systematic review.’, Frontiers in neurology. Switzerland, p. 1056411. doi: 10.3389/fneur.2022.1056411.
Dr Teng Cheng Khoo
(Ghasemi, Razavi and Nikzad, 2017; McGinley, Goldschmidt and Rae-Grant, 2021)
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