Injury to the spinal cord can usher in some unexpected problems. We look at one of those – body temperature!
People who have a spinal cord injury (SCI) often experience abnormal sweating, and when it happens to female patients, they often wonder whether this is a symptom of menopause. That’s not necessarily the case…
The ability of the human body to regulate its temperature – known as thermoregulation – is the function of an area in the brain called the hypothalamus, which is the heat-regulation centre or the “thermostat” of your body. The hypothalamus is situated in the base of the brain and receives messages from thermosensitve receptors in the skin, abdominal organs and spinal cord. So, much like your domestic oven, the temperature of the oven is regulated by the thermostat receiving temperature information and switching the oven element on and off, thus regulating a constant temperature. In SCI the flow of information to the hypothalamus is interrupted and therefore the ability of that individual to self-regulate the body temperature is impaired.
There are several ways in which the human body is able to regulate its temperature. First, when cold, the body reduces the flow of blood to non-vital areas such as the skin and allows the body to conserve heat by reducing temperature loss through radiation. In addition, the body is able to elevate the hairs on the arms and legs (gooseflesh) to trap a layer of warm air between the skin and cold air. Finally, shivering creates warmth by burning what is known as “brown fat”. This is the most efficient means of generating heat in the human body. In SCI individuals, these three mechanisms do not work in areas below the level of the injury; therefore a patient with a spinal lesion will lose heat easily and be susceptible to low body temperature (hypothermia).
On the other hand, when it’s hot, the body can help cool itself by several mechanisms. Vasodilation or increasing the flow of blood to the skin helps to reduce heat by radiation. An intact spinal cord allows the body to sweat, which allows loss of temperature by evaporation. Again, with SCI, these mechanisms do not work well, making the individual susceptible to heatstroke and overheating.
Often sweating can occur profusely in the areas of the body above the level of the injury, which results in drenching. This is thought to be a mechanism triggered to compensate for the loss of thermoregulatory sweating below the level of the lesion. Although this tends to stabilise over time, it can be most uncomfortable. Note that a new onset of abnormal sweating needs further investigation.
Yes, in women it may be a sign of menopausal symptoms but more importantly it may be an indication of a syringomyelia – a cavity filling with fluid in the damaged spinal cord. This condition needs to be managed appropriately.
My take-home message is that thermoregulation in SCI does not function as it should: SCI individuals are prone to excessive heat loss in the colder months and excessive heat gain in the hot summer months. Both can bring risks, and appropriate measures should be taken to prevent hypothermia or heat stroke with appropriate clothing and the use of heating or cooling appliances in susceptible persons.
Dr Ed Baalbergen is the medical officer at the Vincent Pallotti Rehabilitation Centre (Cape Town) and is a member of the International Spinal Cord Society and the Southern African Neurological Rehabilitation Association. email: ed.baalbergen@lifehealthcare.co.za