Uhthoff's phenomenon
Encyclopedia
Uhthoff's phenomenon is the worsening of neurologic
symptom
s in multiple sclerosis
(MS) and other neurological, demyelinating conditions when the body gets overheated from hot weather, exercise, fever
, or saunas and hot tubs. It is possibly due to the effect of increased temperature
on nerve conduction
. With an increased body temperature, nerve impulses are either blocked or slowed down in a damaged nerve but once the body temperature is normalized, signs and symptoms may disappear or improve.
in 1890 as a temporary worsening of vision with exercise in patients with optic neuritis
. Later research revealed the link between neurological signs such as visual loss and increased heat production and Uhthoff's belief that exercise was the etiology
of visual loss was replaced by the conclusions of these later researchers stating that heat was the prime etiology.
and other symptoms such as pain, concentration difficulties, and urinary urgency
when exposed to heat. As a result, many patients with MS tend to avoid sauna
s, warm baths, and other sources of heat or wear ice or evaporative cooling apparel in the form of vests, neck wraps, arm/wrist bands, and hats.
Peripheral nerve studies have shown that even a 0.5°C increase in body temperature can slow or block the conduction of nerve impulses in demyelinated nerves. With greater levels of demyelination, a smaller increase in temperature is needed to slow down the nerve impulse conduction. Exercising and performing activities of daily living can cause a significant increase in body temperature in individuals with MS, especially if their mechanical efficiency is poor due to the use of mobility aids
, ataxia
, weakness, and spasticity
. However, exercise has been shown to be helpful in managing MS symptoms
, reducing the risk of comorbidities, and promoting overall wellness.
Taking advantage of the cooling properties of water may help attenuate the consequences of heat sensitivity. In a study done by White et al. (2000), exercise pre-cooling via lower body immersion in water of 16-17°C for 30 minutes allowed heat sensitive individuals with MS to exercise in greater comfort and with fewer side effects by minimizing body temperature increases during exercise. Hydrotherapy
exercise in moderately cool water of 27-29°C water can also be advantageous to individuals with MS. Temperatures lower than 27°C are not recommended because of the increased risk of invoking spasticity.
Neurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s in multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
(MS) and other neurological, demyelinating conditions when the body gets overheated from hot weather, exercise, fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, or saunas and hot tubs. It is possibly due to the effect of increased temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
on nerve conduction
Nerve conduction velocity
Nerve conduction velocity is the speed at which an electrochemical signal propagates down a neural pathway. Many things can affect this, including axon diameter, myelination, the internal resistance of the axon, and temperature. Nerve conduction velocity differs from species to species, and to a...
. With an increased body temperature, nerve impulses are either blocked or slowed down in a damaged nerve but once the body temperature is normalized, signs and symptoms may disappear or improve.
History
This phenomenon was first described by Wilhelm UhthoffWilhelm Uhthoff
Wilhelm Uhthoff was a German ophthalmologist who was born in Klein-Warin. In 1877 earned his doctorate at the University of Berlin, and later became a professor of ophthalmology at the Universities of Marburg and Breslau , where he succeeded Carl Friedrich Richard Förster .Uhthoff specialized in...
in 1890 as a temporary worsening of vision with exercise in patients with optic neuritis
Optic neuritis
Optic neuritis is the inflammation of the optic nerve that may cause a complete or partial loss of vision.-Causes:The optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of which is relayed to the occipital cortex of the...
. Later research revealed the link between neurological signs such as visual loss and increased heat production and Uhthoff's belief that exercise was the etiology
Etiology
Etiology is the study of causation, or origination. The word is derived from the Greek , aitiologia, "giving a reason for" ....
of visual loss was replaced by the conclusions of these later researchers stating that heat was the prime etiology.
Clinical significance
Many patients with MS experience increased fatigueFatigue (physical)
Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...
and other symptoms such as pain, concentration difficulties, and urinary urgency
Urinary urgency
Urinary urgency is a sudden, compelling urge to urinate. It is often, though not necessarily, associated with urinary incontinence, polyuria, nocturia, and interstitial cystitis. It tends to increase with age...
when exposed to heat. As a result, many patients with MS tend to avoid sauna
Sauna
A sauna is a small room or house designed as a place to experience dry or wet heat sessions, or an establishment with one or more of these and auxiliary facilities....
s, warm baths, and other sources of heat or wear ice or evaporative cooling apparel in the form of vests, neck wraps, arm/wrist bands, and hats.
Peripheral nerve studies have shown that even a 0.5°C increase in body temperature can slow or block the conduction of nerve impulses in demyelinated nerves. With greater levels of demyelination, a smaller increase in temperature is needed to slow down the nerve impulse conduction. Exercising and performing activities of daily living can cause a significant increase in body temperature in individuals with MS, especially if their mechanical efficiency is poor due to the use of mobility aids
Mobility aids
Mobility aids are devices designed to assist walking or otherwise improve the mobility of people with a mobility impairment.There are various walking aids which can help with impaired ability to walk and wheelchairs or mobility scooters for more severe disability or longer journeys which would...
, ataxia
Ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
, weakness, and spasticity
Spasticity
Spasticity is a feature of altered skeletal muscle performance in muscle tone involving hypertonia, which is also referred to as an unusual "tightness" of muscles...
. However, exercise has been shown to be helpful in managing MS symptoms
Multiple sclerosis signs and symptoms
Multiple sclerosis can cause a variety of symptoms: changes in sensation , muscle weakness, abnormal muscle spasms, or difficulty moving; difficulties with coordination and balance; problems in speech or swallowing , visual problems , fatigue and acute or chronic pain syndromes, bladder and bowel...
, reducing the risk of comorbidities, and promoting overall wellness.
Taking advantage of the cooling properties of water may help attenuate the consequences of heat sensitivity. In a study done by White et al. (2000), exercise pre-cooling via lower body immersion in water of 16-17°C for 30 minutes allowed heat sensitive individuals with MS to exercise in greater comfort and with fewer side effects by minimizing body temperature increases during exercise. Hydrotherapy
Hydrotherapy
Hydrotherapy, formerly called hydropathy, involves the use of water for pain-relief and treating illness. The term hydrotherapy itself is synonymous with the term water cure as it was originally marketed by practitioners and promoters in the 19th century...
exercise in moderately cool water of 27-29°C water can also be advantageous to individuals with MS. Temperatures lower than 27°C are not recommended because of the increased risk of invoking spasticity.