Introduction

In the developing world, snake bites are an occupational disease, occurring most commonly among rural male agricultural workers (1, 2). The extremities (3), especial-ly the hand and foot (4-6), are usually bitten. Reports of major amputations proximal to the ankle are more common (4, 7, 8). In the upper limb, however, it is often the digits that are amputated (4, 5). We report the case of a male farmer from Northern Nigeria who had above elbow amputation after a bite in the hand by an uniden-tified snake.

 

Case Report

A 50-year old right-handed, non-diabetic and normo-tensive male farmer presented to Federal Medical Centre, Birnin Kudu in Northern Nigeria, with a dark, blistered, swollen left upper limb (Figure 1) exuding offensive discharge. There was also history of nausea, vomiting and passage of dark urine. Two weeks before presenta-tion he had felt a sudden sting on his left thumb while packing a heap of grass in his farm. Within a few min-utes he started having abnormal sensations in his hand. Fang marks were noted and a fang was removed. Sub-sequently, there was a gradual onset of swelling which progressed from the left hand to mid-arm. He sought initial treatment from a herbalist and a tourniquet was not used. At presentation at our centre, he was febrile (temperature=380C), pale (PCV=24%), jaundiced and had dark urine. His pulse was regular, of good volume, with a rate of 92 beats per minute. His supine blood pressure was 80/50mmHg. There was wet gangrene of the left upper limb up to the mid-arm level. A clinical diagnosis of limb gangrene with septicaemia was enter-tained.

 

He was optimized (fluid resuscitation, blood transfu-sion, tetanus toxoid administration, ceftriaxone and metronidazole commenced) for an emergency above knee guillotine amputation (figure 2). Shoulder abduc-tion exercises were started as soon as pain subsided. The wound, however, continued to discharge and needed further nibbling of distal end of the left humerus, daily dressing, wound cultures and antibiotic changes. The discharge and all signs of sepsis settled in his fourth month of care. He underwent split thickness skin graft-ing of the wound with a 98% take.

 

He was discharged 4 months after presentation with a healed stump and 700 range of shoulder abduction.

 

Discussion

About 1 million snake bites of which there are 500,000 cases of envenoming probably occur annually in Africa (9). An incidence of 600/100,000 population per year has been reported for the Benue valley of Nigeria (10). As in the patient in this case, majority of them occur in male farmers who live in rural areas. The reports by Abubakar et al (4) and Abbas et al (8) are also from the savannah belt of Nigeria. Of 16 amputa-tions in the Abubakar et al report, all 10 amputations in the upper limb were minor while 2 of the 6 in the lower limb were major. Abbas et al reported 2 major lower

 

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limb amputations in paediatric victims of snake bite. In contrast, ours is a report of major upper limb amputa-tion following snake bite. We are not aware of such a report from the savannah belt of Nigeria. Why are major amputations more likely after bites to the lower limbs than the upper limbs? The higher docu-mented incidence in Nigeria (3, 11) of lower limb snake bites is a possible explanation. Reviewing the series by Abubakar et al (4) would however suggest that some ‘protective’ factor(s) for the upper limb seem plausible. We postulate that closer proximity of the upper limb to the heart and the relatively smaller muscle bulk would, respectively, promote more rapid dispersal of snake venom (assuming a tourniquet is not used, as in our pa-tient) and provide smaller amount of tissue necrosis for bacterial proliferation with consequent reduction of the likelihood of major amputation in the upper limb. Tissue necrosis is caused by the various enzymes in snake venom. Compartment syndrome, the unhygienic prehospital intervention often sought by victims in de-veloping countries (4, 8), delay in presentation (4) and bacterial infection may combine with tissue necrosis to make major amputation inevitable. All these factors were in operation in our patient and those of others (4,8). We believe that local envenoming must have been more severe in our patient, overwhelming the ‘protective’ fac-tors. In support of severe envenoming in our patient were local features of envenoming and possible myoglo-binuria or haemoglobinuria occasioning the dark urine. Disability from amputation in a farming environment, poverty and inaccessibility to prostheses has conse-quences. Prevention is imperative. Farmers should wear protective shoes, long trousers and protective gloves while working on the farm. Health education should focus on enjoining victims to report to hospital immedi-ately. Efforts should be made to provide facilities in rural areas (12) and train rural workers in first aid.

 

References

 

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2. Cruz LS, Vargas RV, Lopes AA. Snakebite envenomation and death in the developing world. Eth Dis. 2009; 19 (Suppl 1): S1-42 - S1-46.

3. Omogbai EKI, Nworgu ZAM, Imhafidon MA, et al. Snake Bites in Nigeria: A Study of the prevalence and treatment in Benin City. Trop J Pharmaceut Res 2002; 1(1): 39-44.

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8. Abbas AD, Abubakar AM, Tahir C. Snake-Bite Gangrene in Children: A Report of Two Cases. Journal of Surgical Tech-nique and Case Report 2009; 1(1): 39-41.

9. Chippaux JB. Snakebites: appraisal of the global situation.Bulletin of the World Health Organization 1998: 76(5): 515-524.

10. Pugh RN, Theakston RDG. Incidence and mortality of snake-bite in savannah Nigeria. Lancet 1980; 2: 1181-1183.

11. Njoku CH, Isezuo SA, Makusidi MA. An audit of snakebite injuries seen at the Usmanu Dandodiyo University Teaching Hospital, Sokoto, Nigeria. Niger Postgrad Med J. 2008; 15 (2): 112-115.

12. Habib AG, Abubakar SB. Factors affecting snakebite mortal-ity in north-eastern Nigeria. Int Health (2010); doi:10.1016/j. inhe.2010.08.001

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