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Autoimmune conditions
Published in Ibrahim Natalwala, Ammar Natalwala, E Glucksman, MCQs in Neurology and Neurosurgery for Medical Students, 2022
Ibrahim Natalwala, Ammar Natalwala, E Glucksman
Which of the following most accurately describes the Uhthoff phenomenon in MS? Presence of an electric shock-like sensation down the spine upon flexion of the neckWorsening of symptoms during times when body temperature risesPersistent involuntary flickering of small bundles of the facial musculatureIntense, unpredictable unilateral facial pain that is sharp in character
Answers
Published in Thomas Hester, Iain MacGarrow, Surgical SBAs for Finals with Explanatory Answers, 2018
Two clinical tests used to examine the patient with suspected CTS are Tinel’s, in which tapping the volar wrist over the median nerve may produce paraesthesia in the median distribution of the hand, and Phalen’s test, as described in the question. Chvostek’s sign is positive if tapping over the facial nerve, about 2 cm anterior to the tragus of the ear, causes twitching of the facial muscles. Trousseau’s sign is positive if inflation of a BP cuff above the systolic causes local ulnar and median nerve ischaemia resulting in carpal spasm. Both are clinical signs of hypocalcaemia. Uhthoff’s phenomenon is described in patients with demyelinating disease such as multiple sclerosis; an increase in detected temperature, either on exercise or caused by an external heat source, causes a temporary worsening of neurological symptoms, typically worsening of vision.
Human Perspiration and Cutaneous Circulation
Published in Flavia Meyer, Zbigniew Szygula, Boguslaw Wilk, Fluid Balance, Hydration, and Athletic Performance, 2016
Manabu Shibasaki, Scott L. Davis
MS is a disabling progressive neurological disorder affecting more than 2.3 million people worldwide (National Multiple Sclerosis Society 2014). The pathophysiology of MS results in a demyelination and ultimately loss of axons and disorganization of normal tissue architecture within the CNS by autoimmune injury responses (Frohman, Racke, and Raine 2006). Demyelination is associated with corresponding changes in axonal physiology including a loss of saltatory properties of electrical conduction, a reduction in conduction velocity, and a predisposition to conduction block. Autonomic dysfunction involving the thermoregulatory system is commonly observed in individuals with MS (Haensch and Jorg 2006). The majority of individuals with MS experience transient and temporary worsening of clinical signs and neurological symptoms (Uhthoff’s phenomenon) in response to a number of factors, the most prominent of which are increased ambient/core body temperature and exercise (Uhthoff 1889). It is estimated that 60% to 80% of the MS population experience transient and temporary worsening of clinical signs and neurological symptoms as a result of passive heat exposure, exercise (increase in metabolism), or a combination of both (exercise-heat stress). Typically, deficits caused by increases in temperature are reversible by removing heat stressors and allowing subsequent cooling (Davis et al. 2008).
Understanding and managing autonomic dysfunction in persons with multiple sclerosis
Published in Expert Review of Neurotherapeutics, 2021
Ivan Adamec, Magdalena Krbot Skorić, Mario Habek
Disorder of thermoregulation may have clinical implications as well. It is known that poor thermoregulation leads to transient neurologic dysfunction that occurs when pwMS are exposed to a warm environment, the so-called Uhthoff phenomenon, an episode that needs to be distinguished from an acute relapse of MS. This phenomenon is thought to occur due to a heat-linked blockage of partially demyelinated axons [72]. Worsening of neurological symptoms has been noted even when body temperature is increased by as little as 0.5°C [73]. Furthermore, the lack of ability to cool properly may lead to overheating during exercise that has important implication on how to perform physical rehabilitation in pwMS.
Cryotherapy and self-reported fatigue in individuals with multiple sclerosis: A systematic review
Published in Physical Therapy Reviews, 2019
Annie Campbell, Benjamin Killen, Steven Cialone, Marshall Scruggs, Melanie Lauderdale
Fatigue is a major factor that impacts the quality of life for individuals with MS. Likewise, fatigue has been shown to be exacerbated by increased body temperature, whether exercise-induced or produced by external factors such as ambient temperature [27]. Temperature extremes (too hot or cold) have been shown to impair neural conduction [5], which may be a possible mechanism for fatigue and other symptom exacerbation in individuals with MS [27]. One possible explanation for this exacerbation is Uhthoff’s phenomenon, wherein an acute increase in temperature leads to conduction block of a demyelinated axon. The overall temperature of a nerve is more sensitive when the nerve has been demyelinated, compared to physiologically normal myelinated or unmyelinated nerves [5]. Since the primary pathophysiological mechanism of MS is central demyelination through a prolonged autoimmune-mediated inflammatory response [1], prevention of temperature changes associated with prolonged activity may prevent Uhthoff’s phenomenon. While cooling studies have shown that overcooling can impair nerve conduction [5], the concept of cryotherapy for management of MS symptoms is based on the idea of managing increases in body temperature induced by physical activity [28]. A recent systematic review by Kaltsatou and Flouris [28] showed that cryotherapy improves functional capacity as measured by performance-based outcome measures in individuals with MS. These findings compliment the results of the current study because a decrease in subjective fatigue should improve the capabilities of the person to perform functional tasks. Likewise, the results of the current study may help explain the mechanism by which cryotherapy improves function.
Transient vision loss: a neuro-ophthalmic approach to localizing the diagnosis
Published in Expert Review of Ophthalmology, 2018
Helen Chung, Jodie M. Burton, Fiona E. Costello
Transient visual loss caused by CNS demyelination can last minutes to hours (acute to subacute recovery) versus days to weeks (chronic recovery). In the setting of Uhthoff’s phenomenon, symptoms provoked by increased body temperature may occur with an acute or remote demyelinating optic nerve injury, and recovery often ensues as body temperature normalizes. Acute inflammatory demyelinating lesions of the optic nerve, or more posterior regions of the afferent visual pathway, are associated with localized visual deficits that may take weeks (chronic recovery) to partially, or incompletely resolve.