Extreme heat and excessive sweating

In this issue I want to touch on the effects of extreme heat in people with spinal cord injuries, and on the associated problem of excessive sweating. These issues are often overlooked and can lead to extreme, ongoing discomfort and even quite serious illness.

Somehow it seems that the small things that are easily forgotten by health care workers can end up causing major distress to our patients. Starting first with the effect of excessive heat, it is important to remember that if you have a spinal cord injury, your body's ability to regulate blood flow and temperature is severely impaired below the level of your injury. This is especially true for people with high spinal cord injuries and people with tetraplaegia or quadriplegia.

In an able-bodied person, any extreme rise in environmental temperature may result in some increase in body temperature, but this is easily managed under most conditions. The nervous system is able to programme the limbs and trunk to lose excess heat through increased sweating, and through opening up the network of small blood vessels close to the skin, and in the periphery of the secondary system. This leads to heat loss through evaporation and also through radiation. In all but the most severe of conditions, body temperature is unconsciously and automatically regulated within a safe and comfortable range.

Excessive heat is deadly

In spinal cord injury patients, the body is unable to do this below the level of the injury, because it has no ability to control the amount of sweating, or the opening and closing of blood vessels below the injury level. There is therefore a danger that in excessively hot conditions, the body may heat up excessively. If this heating up is not too bad, it can simply lead to discomfort, but under extreme conditions, it can lead to headaches, dehydration, confusion, seizures and even loss of consciousness and worse.

The take-home message is relatively simple - if you have a spinal cord injury, especially if you have a high level injury, you really need to be aware of the temperature around you, and make sure that you do not expose yourself to excessively hot conditions.

Equally, you and your family or caregivers need to be aware of the dangers of you being exposed to extremely hot conditions over some time. If you inexplicably become confused or ill, one of the possible causes could be that you are suffering from a dangerously elevated body temperature. This would need the urgent attention of a medical doctor, so that you can be properly assessed and managed, if that is the case.

Another important message is that if you do live in an environment that is constantly hot, or if you regularly travel in a vehicle in a very hot environment, it would be wise to consider air conditioning or some other means of controlling the environmental temperature within a reasonable range.

A related problem that people with spinal cord injury complain of is excessive sweating - regardless of the temperature of the environment that they are living in.

Uncomfortable and embarrassing

We know that over 35% of people with spinal cord injuries complain of some degree of excessive sweating. We have come to recognise this pattern of excessive sweating in SCI patients as reflex sweating. Most people who suffer from it report that it is uncomfortable and embarrassing.

Once again, people with tetraplaegia or quadriplegia tend to suffer from this more often, while it is less common in people with lower spinal cord injuries. At this stage, we do not have a clear understanding of the cause of reflex sweating, but it is thought to be due to a combination of compromised temperature regulation and autonomic dysfunction.

Because reflex sweating is provoked through the same mechanisms as autonomic dysreflexia, it is always important to exclude any treatable cause of autonomic dysreflexia before considering any type of symptomatic treatment. Possible common causes that need to be excluded are a blocked catheter, urine retention, constipation, pressure ulcers, any type of infection, bone fractures or even in-growing toenails. Less common, but more important possible causes are syringomyelia, a chronic spinal cord disease which causes nerve disorders, and pulmonary embolus (blocked artery).

Effective treatment is usually possible, but normally would involve some kind of chronic symptomatic medication. The most common medication used is one of the ‘anticholinergic’ drugs like Ditropan (Oxybutinin). These drugs need to be prescribed by a medical doctor.

The take-home message for reflex sweating is that if you do suffer from it, it is worth visiting your doctor to make sure that you have excluded any underlying causes. Once you have done this, if the problem is sufficiently annoying, embarrassing and uncomfortable, effective treatment can be prescribed by your doctor.

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