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suggestive symptom of trismus , or ‘ lockjaw ’, represents what may be a once in a career opportunity to recognise a condition that is taught in medical school and textbooks , but otherwise virtually unseen thanks to the effectiveness of widespread immunisation .
Thankfully , tetanus remains a rarity in Australia . Between 2003-19 , the average annual notification rate was 0.02 per 100,000 population , and the average annual hospitalisation rate was 0.05 per 100,000 . 1 It may affect patients of all ages , but in the Australian setting tetanus is mainly seen in adults who have never been vaccinated or vaccinated more than 10 years ago . Rare cases have been reported in immunised patients . The Australian case-fatality rate is 2 %. 2
Tetanus is caused by Clostridium tetani , a spore-forming anaerobic bacterium found in soil and mammalian gastrointestinal tracts . C tetani produces a potent neurotoxin , tetanospasmin , which causes violent spastic paralysis by blocking GABA release . GABA is an inhibitory neurotransmitter when acting on motor neurons . Blockade results in muscular rigidity due to increased resting firing rate of motor neurons and generates spasm by modifying reflex responses to afferent stimuli . 3
Infection may follow a recognised contaminated injury or a trivial wound and in 15-25 % of patients there is no evidence of a recent wound . 3 Other risk factors include dental procedures , surgery , IM injections , IV drug use and burns . The incubation period ranges from three days to three weeks . 2 , 3
Generalised tetanus is the most common and severe form accounting for more than 80 % of cases . 3 Other clinical manifestations include neonatal , cephalic and localised tetanus . Generalised tetanus typically presents in a descending pattern , with trismus followed by neck stiffness , difficulty swallowing and abdominal muscle rigidity . 3 In early phases of the disease , features of autonomic overactivity such as sweating and tachycardia may be
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present . In later stages , profuse sweating , cardiac arrhythmias , labile blood pressure and fever are frequent . 4 Patients develop tonic skeletal muscle contraction and intermittent intense muscular spasm , which are intensely painful , as consciousness is preserved . Tetanic spasm may be triggered by sensory stimuli such as loud noises , physical contact or light . During spasm , laryngospasm and apnoea may occur . 4
The diagnosis is clinical , based on the characteristic features in patients at risk , including those with an uncertain or lapsed vaccination history ( booster > 10 years previously ). 2 While C . tetani may be cultured from contaminated wounds or blood culture , false negatives are common , and testing should not defer or alter management in suspected cases .
Differential diagnoses for dystonia and trismus include drug induced dystonia , dental-associated trismus , strychnine poisoning ( which results in a similar clinical picture to tetanus ) and malignant neuroleptic syndrome .
Australian treatment guidelines recommend IV tetanus immunoglobulin ( 4000 IU via slow infusion ) for patients with clinical tetanus . IM immunoglobulin is recommended for those with tetanus prone wounds who are at risk of tetanus ( eg , un- or under-vaccinated , immunocompromised ). 2 This is sourced via local blood bank services . Immunoglobulin neutralises unbound toxin but does not confer any enduring immunity . Active immunisation is thus also essential to prevent recurrent infection .
In cases of tetanus , any clearly contaminated wound sources may warrant debridement and antibiotic treatment . Supportive measures to manage rigidity and tetanic spasm and complications such as laryngospasm , fractures , hypertension , nosocomial infections , pulmonary embolism and aspiration pneumonia are warranted in severe disease . 3 , 5
References on request from kate . kelso @ adg . com . au
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Molecule of tetanus neurotoxin .
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ANSWER The answer is a . This facial rash , which appeared after waxing , with intermittent pruritus , is consistent with a clinical diagnosis of tinea faciei . Tinea faciei is caused by a variety of dermatophytes , which thrive in warm , moist environments . In this case , waxing the area likely resulted in disruption to the skin barrier and created an opportunity for fungal infection to occur . Pruritus is a characteristic symptom of cutaneous fungal infections .
Although the patient has features consistent with chronic atopic dermatitis of the neck and cubital fossa , dermatitis is less likely to be the cause of the periorbital rash . In this area , the rash is more sharply demarcated and demonstrates peripheral accentuation of the scale , which is more classic for a fungal infection .
Psoriasis is less likely because it typically presents with discrete , well demarcated , erythematous scaly papules and plaques . It can affect various parts of the body , including the face , but is more common over extensor surfaces and the scalp . The nails may also be involved .
Rosacea is less likely because it is characterised by facial erythema and flushing , with or without pustules and papules . In this setting , the facial and upper back comedones are most consistent with acne .
Skin scraping from the lesions for microscopy , culture and sensitivity , and PCR , will aid diagnosis of dermatophyte infection . Fungal hyphae may be seen on initial microscopy and cultured for identification . Some laboratories now also offer PCR testing which is more sensitive and specific . Topical terbinafine is the recommended treatment for tinea faciei such as in this case , due to its specific antifungal action , targeted application , and established efficacy . Combination topical steroids and antifungals are not recommended , and are thought to contribute to treatment-resistance , which is developing worldwide .
Generally , three weeks of therapy is sufficient for response . However , some cases of tinea faciei , particularly those that are more extensive , severe or unresponsive to initial treatment , may require an extended treatment course of up to six weeks . This longer duration is usually reserved for cases where the infection has proven to be more stubborn or widespread .
References on request from kate . kelso @ adg . com . au
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