Severe hypophosphatemia and acute neurologic dysfunction in a marathon runner

It's in the game: A review of neurological lesions associated with sports

INTRODUCTION

The practice of sports may lead to neurological injuries. While relatively uncommon (overall incidence of approximately 2.5%), and mostly benign and transient, some conditions may be life-threatening and permanent. Thus, both clinical neurologists and sports physicians should be aware of their existence and relevance. We aimed to review all sports-related neurological injuries and illnesses reported in the literature.

METHODS

Following SANRA guidelines, we performed a narrative review and searched PubMed and Scopus databases. Relevant sports were selected based on their recognition as an Olympic sport by the International Olympic Committee. Chronic traumatic encephalopathy (CTE) and other neurodegenerative disorders were not included.

RESULTS

A total of 292 studies were included concerning 33 different sports. The most reported neurological injury was damage to the peripheral nervous system. Traumatic injuries have also been extensively reported, including cerebral haemorrhage and arterial dissections. Non-traumatic life-threatening events are infrequent but may also occur, e.g. posterior reversible encephalopathy syndrome, cerebral venous thrombosis, and arterial dissections. Some conditions were predominantly reported in specific sports, e.g. yips in baseball and golf, raising the possibility of a common pathophysiology. Spinal cord infarction due to fibrocartilaginous embolism was reported in several sports associated with minor trauma.

CONCLUSION

Sports-related neurological injuries are increasingly receiving more social and medical attention and are an important cause of morbidity and mortality. This review may serve as a guide to physicians managing these challenging situations.

Approach to patients with hypophosphataemia

Phosphate metabolism is an evolving area of basic and clinical research. In the past 15 years, knowledge on disturbances of phosphate homoeostasis has expanded, as has the discovery of new targeted therapies. Hypophosphataemia might be the biochemical finding in several diseases, and its clinical evaluation should initially focus on the assessment of pathophysiological mechanisms leading to low serum phosphate concentrations. Clinical consequences of hypophosphataemia can involve multiple organ systems and vary depending on several factors, the most important being the underlying disorder. This Review focuses on the approach to patients with hypophosphataemia and how underlying pathophysiological mechanisms should be understood in the evaluation of differential diagnosis. We define an algorithm for the assessment of hypophosphataemia and review the most up-to-date literature on specific therapies. Continuous research in this area will result in a better understanding and management of patients with hypophosphataemia.

Hypophosphataemia in confused half-marathon runners: A report of two cases

Introduction:

Severe hypophosphataemia may occur in long distance runners presenting to Accident & Emergency (A&E) department with exertional heat illness.

Case presentation:

A 46-year-old man who collapsed in half marathon race was found to have raised body temperature (38.8°C) and confused with memory loss in the Accident & Emergency department. His amnesia was persistent even after his body temperature was normalized. He was found to have severe hypophosphataemia (0.21 mmol/L; reference range: 0.74 - 1.4 mmol/L). He had a neurological recovery after phosphate replacement. Another 45-year-old female half marathon runner was found to have moderate hypophosphataemia (0.5 mmol/L) co-presenting with exertional heat illness.

Discussion:

Moderate to severe hypophosphataemia complicated the clinical picture of the two cases presented with exertional heat illness. Causes of hypophosphataemia in runners are multifactorial.

Conclusion:

Emergency physician should be alert of profound hypophosphataemia as a complication in heat exertional illness.

Unveiling a hidden 31 P signal coresonating with extracellular inorganic phosphate by outer-volume-suppression and localized 31 P MRS in the human brain at 7T

PURPOSE

The study was undertaken to demonstrate that there is more than 1 component in the extracellular Pi31 P signal ( Piex) acquired from human head using nonlocalized 31 P MRS.

METHODS

Outer-volume-suppression (OVS) saturation and 1D/2D 31 P CSI were utilized to reveal the presence of an additional component in the Piex signal.

RESULTS

67% of the head extracellular Pi signal was attenuated upon OVS saturation of the peripheral meningeal tissues, likely reflecting elimination of the Pi signal in the meningeal fluids (the blood and CSF). Localized 1D/2D CSI data provided further support for this assignment. Upon correction for the meningeal contribution, the extracellular Pi concentration was 0.51 ± 0.07 mM, whereas the intracellular Pi was 0.85 ± 0.10 mM. The extracellular pH was measured as 7.32 ± 0.04 when using OVS, as compared to 7.39 ± 0.03 when measured without OVS (N = 7 subjects).

CONCLUSION

The extracellular Pi signal acquired from the human head using nonlocalized 31 P MRS contains a significant component likely contributed by peripheral blood and CSF in meninges that must be removed in order to use this signal as an endogenous probe for measuring extracellular pH and other properties in the brain.

Phosphate homeostasis and disorders

Recent studies of inherited disorders of phosphate metabolism have shed new light on the understanding of phosphate metabolism. Phosphate has important functions in the body and several mechanisms have evolved to regulate phosphate balance including vitamin D, parathyroid hormone and phosphatonins such as fibroblast growth factor-23 (FGF23). Disorders of phosphate homeostasis leading to hypo- and hyperphosphataemia are common and have clinical and biochemical consequences. Notably, recent studies have linked hyperphosphataemia with an increased risk of cardiovascular disease. This review outlines the recent advances in the understanding of phosphate homeostasis and describes the causes, investigation and management of hypo- and hyperphosphataemia.