Electrical injury and amyotrophic lateral sclerosis: a systematic review of the literature

Abstract

Electrical injury may act as a potential precipitating or risk factor for amyotrophic lateral sclerosis (ALS). A systematic review of the literature was undertaken to assess the relationship between electrical injury and the development of ALS. Information for the review was obtained using five medical databases, and from manual searching of individual papers. Patients presenting with a neurological syndrome after electrical injury, including lightning, were included and classified into four categories: ALS; progressive upper motor neurone (UMN) syndrome; progressive lower motor neurone (LMN) syndrome; and non-progressive syndrome. Linear regression and chi2 testing were used for analysis of the data. 96 individuals, comprising 44 with ALS, 1 with a progressive UMN syndrome, 7 with a progressive LMN syndrome and 44 with a non-progressive syndrome, were identified from 31 papers with publication dates between 1906 and 2002. The median interval between electrical injury and disease onset was 2.25 years for all progressive syndromes and just over 1 week for the non-progressive syndrome. The more severe the shock (excluding lightning), the more likely individuals were to have a non-progressive motor syndrome. A non-progressive spinal cord syndrome is associated with more severe electrical injury. Overall, the evidence reviewed does not support a causal relationship between ALS and electric shock.

Case-control study of occupational exposure to electric shocks and magnetic fields and mortality from amyotrophic lateral sclerosis in the US, 1991–1999

“…Lending support that severity could play a factor, Cruz et al 26 also found that the ALS OR among those with one ES without injury was 1.2 (95% CI ¼ 0.6-1.4) and multiple ES without injury was 0.7 (95% CI ¼ 0.5-1.1). In a review of electrical injury case reports and studies, Abhinav et al 27 found that stronger ES resulted in nonprogressive MND whereas mild ES in progressive ALS. In future work, severity scale might be added to the ES JEM to examine associations across severe to mild ES levels.…”

What causes amyotrophic lateral sclerosis?

“…It is not clear whether having higher levels of physical activity raises the risk of ALS and, if it does, whether it is the activity itself or being genetically predisposed to high sporting prowess that is the mechanism 96 . Similarly, electric shock is not a risk factor in some analyses but is in others 97, 98 . There is mixed evidence for the involvement of chemicals, such as heavy metals, ambient aromatic hydrocarbons, pesticides, and cyanotoxins 99– 103 .…”

Electrical injury to the brain: Figure 1

“…Typically, the onset is early after the injury, the complaints do not progress and location of the damage relates to the entry or exit point of the electric shock, suggesting a causal relationship between injury and neurological disease. Other case reports describe late-onset (median 2.25 years after injury) progressive disease diagnosed as amyotrophic lateral sclerosis, for which a causal relationship between the electrical injury and disease is under debate 4. Although we consider stroke unlikely in our patient, ischaemic stroke can occur after electrical injury due to cardiac arrhythmias or current-induced vasospasms 5…”