Spinal cord injuries (SCI) classically affect function – movement, control and sensation – of all parts of the body which use the nerves at and below the level of injury. This means that, although the brain’s communication with some parts of the body may be permanently and partially or completely obstructed, there is not necessarily any effect on pure brain function.
In some instances, a traumatic incident which results in SCI may also cause traumatic brain injury (TBI); the number of people who suffer both injuries seems to be increasing[i]. There is also a risk of brain injury without obvious evidence on medical scans – ‘occult brain injury’[ii] being overlooked or underdiagnosed, and symptoms being ascribed purely to the spinal cord injury.
However, even when an acute injury is clearly below the level of the brain and there was no direct injury to the head, some people do find that they develop degrees of memory loss, altered thought processes, and ‘brain fog’. The effects of a spinal cord injury can, therefore, have short- or long-term effects on certain cognitive function[iii].
Many people who experience spinal cord injury have no cognitive symptoms at all, and lead full, rewarding lives with adjustments for any new physical needs. Indeed, people with cognitive impairment should also be able to expect to lead the kind of life they want to with adjustments and support for any changes in their ability.
Symptoms like memory loss, cognitive impairment, and fatigue may have a profound effect on a person’s contentment and quality of life. There are many incredible adjustments that can be made to enable a person to engage in normal activities despite physical restrictions and even very complex care needs. However, overcoming cognitive and psychological barriers can be even more complicated.
The association between spinal cord injury and cognitive impairment is often overlooked. Perhaps this is because the effects on other parts of the body can be so profound; advice and management after a spinal cord injury focuses on maximising independence and quality of life by managing physical changes and restrictions. A failure to recognise and understand the cognitive changes that sometimes accompany a spinal cord injury can make people living with these symptoms feel very isolated; understanding a condition makes it easier to live with that condition.
How do Spinal Cord Injuries Affect Brain Function?
The likely reasons for changes in brain function after a spinal cord injury are complex and multifaceted. Someone who sustains a spinal cord injury with no direct effect on the brain might still notice some symptoms relating to their thought processes and memory. Some of the factors that are thought to cause cognitive symptoms include:
- Inflammatory changes triggered by spinal cord injury which can affect the entire central nervous system.
- Management of chronic post-SCI symptoms[iv] with strong painkillers, antidepressants, or other medications which might cause drowsiness, memory problems or mood changes.
- Damage from reduced oxygen supply, either from respiratory arrest at the time of the injury or subsequent difficult airway or ventilation management.
- The mental health impact of a traumatic injury or when adapting to life with a spinal cord injury.
Inflammatory Complications
Spinal cord injury causes inflammation which can affect the whole nervous system – this includes the brain, and the brain can be very sensitive to inflammation and pressure. The effects of spinal cord injury on the brain have been studied in animal models[v], and have a strong correlation to apparent changes in mood and problem-solving processes.
Using animal models to study mood and thought patterns comes with obvious restrictions; without verbal and other forms of communication which are inherently and exclusively human, effective assessment of the impact on higher brain processes is difficult.
What the studies do show, however, is that a precise injury below the level of the spinal cord that should directly affect the brain does cause changes in processing and behaviour, and that this seems to be related to an inflammatory process which can affect the whole nervous system.
The Effect of Medications
A spinal cord injury can have a profound and widespread effect on physical health, and polypharmacy[vi] – the use of a high number of different types of medication – is very common after an SCI. Some of the medications commonly used long-term for people with a spinal cord injury can have a significant impact on the way a person feels.
Any medicines that affect sleep patterns and mood can cause changes in the way a person functions. Medicines that make people drowsy particularly cause feelings of fatigue, and difficulty concentrating, and even changes in word-finding and simple problem-solving abilities.
The sheer number of medications people typically take after an SCI is associated with a high risk of side-effects[vii]. Medications commonly prescribed for symptoms after a spinal cord injury which can cause apparent changes in brain function include:
Opiates: Many medications for pain can affect mental clarity and cause extreme fatigue and problems concentrating. Opioid medicines[viii] in particular come in a range of forms, long- and short-acting, and are associated with drowsiness and ‘brain fog’.
Anti-convulsants: These are commonly used in the management of pain following spinal cord injury. Gabapentin and Pregabalin have been proved to be especially effective in decreasing neuropathic pain and other secondary outcomes in people with spinal cord injuries.
Anti-convulsant medications have side effects that produce symptoms commonly associated with brain injury and cognitive impairment: patients given Gabapentin are significantly more likely to experience dizziness, somnolence and, less frequently, ataxia including slurred speech, gait disturbance, stumbling and lack of coordination. However, these symptoms appear to be transient.
Anti-depressants: Common antidepressants and medications to help stabilise the mood include:
- Selective Serotonin Reuptake Inhibitors (SSRIs) such as citalopram, fluoxetine, and sertraline.
- Tricylic drugs – like amitriptyline and clomipramine.
- Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs) such venlafaxine and duloxetine.
- Benzodiazepines – often used for anxiety or to help with sleeping problems, diazepam, temazepam, and lorazepam are all common benzodiazepines.
Nearly all medications prescribed specifically for mood and mental health conditions have reported side effects including fatigue and concentration difficulty. The side effects of these drugs, however, often closely mimic some of the symptoms commonly associated with the depression and mood disorders they are intended to treat. Weighing up the risks and benefits of taking antidepressant medication is sometimes a matter of trial and error; although the side effects of drugs used in mental health medicine can be significant, antidepressants can also be lifesaving.
Anti-spasmodics: Spasticity affects roughly two thirds of patients with spinal cord injury. This is characterised by exaggerated tendon stretch reflexes and involuntary muscle spasms.
Antispasmodics (also commonly called anticholinergics) and muscle relaxants can be used to reduce the effects of spasticity after spinal cord injury.
Commonly used antispasmodic medications include temazepam, clorazepate, baclofen, phenobarbital, tizanidine, cyclobenzaprine and metaxalone.
Use of antispasmodic medication in the treatment of post trauma spinal cord injury patients has a negative impact on neurological and functional outcomes at and after discharge. Antispasmodic medications work to reduce spasticity by inhibiting neural networks and neural activity. Recovery from acute SCI and other injuries to the central nervous system is determined by neural plasticity which depends upon neural activity.
While spasticity affects two thirds of patients with spinal cord injury only a minority of those report that it appreciably effects their quality of life and it seems that clinicians may prescribe medications for signs of spasticity without consideration of the long term reduction in neurological functioning.[ix]
Hypoxic Brain Injury
A high spinal cord injury can have a serious and severe impact on a person’s ability to breathe independently. A period of reduced ventilation or respiratory arrest following a spinal cord injury – for example, if there is any delay in medical care – can cause profound brain injury as a secondary result of a spinal cord injury.
Acute hypoxic brain injury – damage to the brain caused by a lack of oxygen supply – may resolve fully or partially, but extended periods with a lack of oxygen to the brain can cause irreversible damage. This secondary effect can cause changes in mood, behaviour, even personality.
As a direct secondary effect, the link between high spinal cord injury and lack of oxygen to the brain seems straightforward. There are also other mechanisms which might be considered a ‘tertiary’ effect of SCI on the brain – for example, the longer-term changes in nervous system control in people with injuries above T1 – the top vertebra of the thoracic spine – are associated with low blood pressure (hypotension) and a slow heart rate (bradycardia). Some association has been shown between these kind of cardiovascular findings and impaired cognitive function[x].
Mental Health Problems
Whether or not a spinal cord injury has physical effects on the brain, the impact of any serious life-changing event can have a significant impact on mental health. People with acute or chronic mental illness, particularly major depression, consistently show worse results in tests for memory and cognitive function than they do when they have good, stable mental health. This is irrespective of any other health problems, but the high rates of depression experienced among people with spinal cord injury mean that the effects of mental illness on cognitive function are likely to have a considerable impact on some people with spinal cord injury.
Autonomic Dysreflexia
Autonomic Dysreflexia (AD) describes a situation where the body’s unconscious nervous system has an exaggerated and uncontrolled reflex response to a problem, a damaging or irritating stimulus. This response can cause very elevated blood pressure (hypertension) leading to seizures, stroke and cardiac arrest.
Individuals with a spinal core injury are at high risk of AD: the direct risk caused by the nerve damage of their initial injury. This means they have the potential to experience serious physical problems without any sensation or ‘early warning signs.’ Indirectly, they are at higher risk of AD because of the results of their neurological injury – a higher likelihood of bowel or bladder dysfunction, for example.
AD can cause delirium and other symptoms associated with neurological functioning. This should, however, be able to be resolved by the quick and effective identification and treatment that is critical to deal with AD.
Symptoms of AD should be treated as a medical emergency. Having a care package with a dedicated team who can provide continuity of care – a partnership with an individual, a family, and carers – means that everyone involved in a person’s care is in a good position to spot signs of AD.
Avoidance and treatment of AD relies upon good nursing care: monitoring the patient’s symptoms, bowel and bladder emptying, skin and pressure care – support with positional changes and identifying early signs of high blood pressure and heart rate.
Living with Cognitive Impairment
People do report symptoms like brain fog and memory problems after spinal cord injuries, and there are certainly reasons why that might happen. However, it is important to remember that for many people, an injury that only affects the spinal cord does not cause cognitive symptoms.
This is reassuring for many, but also a sign that people who are experiencing memory or mood problems should report their symptoms to their doctors, as there may be ways of improving the symptoms or further investigating the cause. There are many potential chronic post-SCI complications[xi][xii] which can cause or exacerbate cognitive dysfunction, and careful management with continued input from specialist neurological rehabilitation teams is important.
Anyone with a significant spinal cord injury, especially higher injuries affecting breathing, can benefit from a comprehensive care package with a team of nurses and healthcare assistants who have had specialist training in the care of people with complex care needs after a spinal cord injury. Care and input from family members can also be helpful for some people.
Having the option of full professional support, however, can help everybody maintain the kind of relationships they value the most. The resilience of family and close social circles after traumatic, life-changing injuries cannot be valued highly enough[xiii] and professional carers understand and bolster those support networks.
[i] Hagen, E. M., Eide, G. E., Rekand, T., Gilhus, N. E., & Gronning, M. (2010). Traumatic spinal cord injury and concomitant brain injury: a cohort study. Acta Neurologica Scandinavica, 122, 51-57. https://doi.org/10.1111/j.1600-0404.2010.01376.x
[ii] Macciocchi, S., Seel, R. T., Thompson, N., Byams, R., & Bowman, B. (2008). Spinal cord injury and co-occurring traumatic brain injury: assessment and incidence. Archives of physical medicine and rehabilitation, 89(7), 1350-1357. https://doi.org/10.1016/j.apmr.2007.11.055
[iii] Heled, E., Tal, K., & Zeilig, G. (2020). Does lack of brain injury mean lack of cognitive impairment in traumatic spinal cord injury?. The Journal of Spinal Cord Medicine, 1-8. https://doi.org/10.1080/10790268.2020.1847564
[iv] Sezer, N., Akkuş, S., & Uğurlu, F. G. (2015). Chronic complications of spinal cord injury. World journal of orthopedics, 6(1), 24–33. https://doi.org/10.5312/wjo.v6.i1.24
[v] Wu, J., Zhao, Z., Sabirzhanov, B., Stoica, B. A., Kumar, A., Luo, T., Skovira, J., & Faden, A. I. (2014). Spinal cord injury causes brain inflammation associated with cognitive and affective changes: role of cell cycle pathways. The Journal of neuroscience : the official journal of the Society for Neuroscience, 34(33), 10989–11006. https://doi.org/10.1523/JNEUROSCI.5110-13.2014
[vi] Cadel, L., C. Everall, A., Hitzig, S. L., Packer, T. L., Patel, T., Lofters, A., & Guilcher, S. J. (2020). Spinal cord injury and polypharmacy: a scoping review. Disability and rehabilitation, 42(26), 3858-3870. https://doi.org/10.1080/09638288.2019.1610085
[vii] Kitzman, P., Cecil, D., & Kolpek, J. H. (2017). The risks of polypharmacy following spinal cord injury. The Journal of Spinal Cord Medicine, 40(2), 147-153. https://doi.org/10.1179/2045772314Y.0000000235
[viii] Cardenas, D. D., & Jensen, M. P. (2006). Treatments for chronic pain in persons with spinal cord injury: A survey study. The journal of spinal cord medicine, 29(2), 109–117. https://doi.org/10.1080/10790268.2006.11753864
[ix] Theriault, E. R., Huang, V., Whiteneck, G., Dijkers, M. P., & Harel, N. Y. (2018). Antispasmodic medications may be associated with reduced recovery during inpatient rehabilitation after traumatic spinal cord injury. The journal of spinal cord medicine, 41(1), 63–71. https://doi.org/10.1080/10790268.2016.1245010
[x] Wecht, J. M., & Bauman, W. A. (2013). Decentralized cardiovascular autonomic control and cognitive deficits in persons with spinal cord injury. The journal of spinal cord medicine, 36(2), 74-81.
https://doi.org/10.1179/2045772312Y.0000000056
[xii] Jensen, M. P., Kuehn, C. M., Amtmann, D., & Cardenas, D. D. (2007). Symptom burden in persons with spinal cord injury. Archives of physical medicine and rehabilitation, 88(5), 638–645. https://doi.org/10.1016/j.apmr.2007.02.002
[xiii]Simpson, G., & Jones, K. (2013). How important is resilience among family members supporting relatives with traumatic brain injury or spinal cord injury?. Clinical rehabilitation, 27(4), 367-377. https://doi.org/10.1177%2F0269215512457961
