title: Neurotoxicity in Russell's viper (Daboia russelii) envenoming in Sri Lanka: a clinical and neurophysiological study.
abstract: BACKGROUND
  Russell's viper is more medically important than any other Asian snake, due to number of envenoming's and fatalities. Russell's viper populations in South India and Sri Lanka (Daboia russelii) cause unique neuromuscular paralysis not seen in other Russell's vipers.
  
  
  OBJECTIVE
  To investigate the time course and severity of neuromuscular dysfunction in definite Russell's viper bites, including antivenom response.
  
  
  METHODS
  We prospectively enrolled all patients (>16 years) presenting with Russell's viper bites over 14 months. Cases were confirmed by snake identification and/or enzyme immunoassay. All patients had serial neurological examinations and in some, single fibre electromyography (sfEMG) of the orbicularis oculi was performed.
  
  
  RESULTS
  245 definite Russell's viper bite patients (median age: 41 years; 171 males) presented a median 2.5 h (interquartile range: 1.75-4.0 h) post-bite. All but one had local envenoming and 199 (78%) had systemic envenoming: coagulopathy in 166 (68%), neurotoxicity in 130 (53%), and oliguria in 19 (8%). Neurotoxicity was characterised by ptosis (100%), blurred vision (93%), and ophthalmoplegia (90%) with weak extraocular movements, strabismus, and diplopia. Neurotoxicity developed within 8 h post-bite in all patients. No bulbar, respiratory or limb muscle weakness occurred. Neurotoxicity was associated with bites by larger snakes (p < 0.0001) and higher peak serum venom concentrations (p = 0.0025). Antivenom immediately decreased unbound venom in blood. Of 52 patients without neurotoxicity when they received antivenom, 31 developed neurotoxicity. sfEMG in 27 patients with neurotoxicity and 23 without had slightly elevated median jitter on day 1 compared to 29 normal subjects but normalised thereafter. Neurological features resolved in 80% of patients by day 3 with ptosis and weak eye movements resolving last. No clinical or neurophysiological abnormality was detected at 6 weeks or 6 months.
  
  
  CONCLUSIONS
  Sri Lankan Russell's viper envenoming causes mild neuromuscular dysfunction with no long-term effects. Indian polyvalent antivenom effectively binds free venom in blood but does not reverse neurotoxicity.
authors.affiliation: a Monash Venom Group, Department of Pharmacology , Monash University , Clayton , VIC , Australia ;|b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka ;|c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka ;
authors.forename: Anjana
authors.initials: A
authors.lastname: Silva
authors.affiliation: c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka ;|d Clinical Toxicology Research Group , University of Newcastle , Callaghan , NSW , Australia ;
authors.forename: Kalana
authors.initials: K
authors.lastname: Maduwage
authors.affiliation: c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka ;
authors.forename: Michael
authors.initials: M
authors.lastname: Sedgwick
authors.affiliation: b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka ;
authors.forename: Senaka
authors.initials: S
authors.lastname: Pilapitiya
authors.affiliation: b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka ;
authors.forename: Prasanna
authors.initials: P
authors.lastname: Weerawansa
authors.affiliation: b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka ;
authors.forename: Niroshana J
authors.initials: NJ
authors.lastname: Dahanayaka
authors.affiliation: c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka ;|e Clinical Pharmacology , University of Sydney , Sydney , NSW , Australia.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Buckley
authors.affiliation: b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka ;
authors.forename: Sisira
authors.initials: S
authors.lastname: Siribaddana
authors.affiliation: c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka ;|d Clinical Toxicology Research Group , University of Newcastle , Callaghan , NSW , Australia ;
authors.forename: Geoffrey K
authors.initials: GK
authors.lastname: Isbister
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000997:Antivenins / Q000627:therapeutic use; D004576:Electromyography; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D020258:Neurotoxicity Syndromes / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D015995:Prevalence; D011446:Prospective Studies; D017840:Daboia; D012909:Snake Bites / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D013188:Sri Lanka; D014757:Viper Venoms / Q000097:blood / Q000633:toxicity; D055815:Young Adult
chemical_list: D000997:Antivenins; D014757:Viper Venoms
keywords: Antivenom; Daboia russelii; paralysis; single fibre electromyography