Uhthoff's phenomenon as the initial symptom in neuromyelitis optica spectrum disorders: a case report

• Published in: Hong Kong medical journal = Xianggang yi xue za zhi 2023-06, Vol.29 (3), p.259
• Main Authors: Liang, H, Xus, C, Xu, J
• Format: Article
• Language: English
• Subjects: Antibodies; Aquaporins; Blood; Body temperature; Case reports; Catheters; Cerebrospinal fluid; Conflicts of interest; Exercise; Heat; Leukocytes; Magnetic resonance imaging; Mental disorders; Multiple sclerosis; Neurology; Pathophysiology; Patients; Physiology; Spinal cord; Urology
• ISSN: 1024-2708; 2226-8707
• DOI: 10.12809/hkmj219977

Figure. (a and b) Axial fluid attenuated inversion recovery sequence and (c and d) T2 sequence images demonstrating hyperintense signals in right brachium pontis, brainstem, and left parietal lobe (arrows). (e) T2 sequence image showing hyperintense signals from C6 to T1 (arrow). (f and g) T1 sequence images demonstrating hypointense signals in brachium pontis, brainstem, and left parietal lobe (arrows) Discussion German professor Wilhelm Uhthoff described the phenomenon of transitory visual disturbance in 1890 in patients with multiple sclerosis (MS) occurring after physical exercise and an increase in body temperature. In 1961, G Ricklefs named this phenomenon Uhthoff's phenomenon (UP),1as Uhthoff observed the appearance of reversible optic symptoms induced by an increase in body temperature in four of 100 patients with MS and described it as the ‘prominent deterioration of visual acuity during physical exercise and exhausting activity'.2 Subsequent observations revealed that the physiological mechanism of visual dysfunction during heat exposure was the same as that of various other neurological symptoms experienced by MS patients. Uhthoff's phenomenon is most commonly observed in individuals with MS but can also occur in those with NMOSDs.3 To date, the exact mechanisms of UP have remained unclear; however they likely involve a combination of structural and physiological changes within the demyelinated axons in the central nervous system that occur in the presence of a raised core body temperature.4 Factors including exercise, taking a hot bath or shower, fever, exposure to sun, menstrual cycle, psychological stress, and hot meals may worsen the symptoms in MS or NMOSD.5 A study reported UP as the first manifestation of MS in an adult male who presented with blurred vision after performing intense exercise in the fitness room.6 Another study reported three episodes of oscillopsia that occurred while a 17-year-old man participated in intense sports in summer (which was interpreted as recurrent UP); the man was finally diagnosed with radiologically isolated syndrome.7To date, no studies have reported UP as the initial symptom in individuals with NMOSDs.