An old woman with pressure ulcer, rigidity, and opisthotonus: never forget tetanus!

0 / 5 (0 votos)

Fuente: The Lancet Neurology

In April, 2014, a 77-year-old woman with advanced Alzheimer’s disease and type 2 diabetes was admitted to our geriatrics unit with fever. She lived at home with a carer and had been bedridden for 2 months. She had a stage 4 sacral pressure ulcer that had recently been debrided and treated with amoxicillin-clavulanic acid because of Enterococcus faecalis infection. On admission, chest radiograph showed left lung opacity consistent with pneumonia and she was started on piperacillin-tazobactam and vancomycin. A week after admission she developed intermittent generalised rigidity, opisthotonus (hyperextension of the neck and trunk), flexion of the upper limbs, extension of the lower limbs, trismus (lockjaw), and risus sardonicus (smile-like retraction of the lips). She would suddenly adopt these abnormal postures, often after sensory stimulation such as noise, light, or touch. She was not taking neuroleptics or other drugs that can cause parkinsonism. Head CT showed no acute lesions, cerebrospinal fluid and serum ionised calcium were normal. In view of the characteristic findings on neurological examination and history of infected skin ulcer we diagnosed tetanus, and her son confirmed that she had not received a tetanus vaccine booster for 30 years. We gave a dose of intramuscular tetanus and diphtheria toxoid, intramuscular human tetanus immune globulin 500 U, intravenous metronidazole 500 mg four times daily, and clonazepam 0·7 mg three times daily via nasogastric tube, and she had a repeat surgical debridement of the sacral ulcer. 1 week later her rigidity and spasms had reduced in severity and frequency. However, unfortunately she developed sepsis and died 3 weeks later. Blood cultures grew acinetobacter and enterococcus.

Tetanus is caused by the toxin of the anaerobic bacterium Clostridium tetani (figure). The spores enter the host though breaks in the skin, particularly necrotic wounds and those made by penetrating foreign bodies. The toxin blocks central inhibitory GABAergic neurotransmission, causing excessive tonic muscle contraction with superimposed spasms. Cognition is characteristically spared. Tetanus can be found on PCR and bacterial culture but the diagnosis is essentially clinical.1 Although several pathological conditions can lead to subacute generalised stiffness and spasms (appendix) the pattern of muscle rigidity is unique in tetanus, consisting of opisthotonus, trismus, and risus sardonicus. Tetanus is now rare in industrialised countries, but incidence is higher among the elderly because of inadequate immunisation. Diabetes is a predisposing factor.2, 3 594 cases were reported in Italy between 2001 and 2010 and older women were at higher risk, probably because of fewer opportunities for vaccination.4 There is little evidence supporting specific treatment and few randomised trials have been done.

Clostridium tetani. False-colour transmission electron micrograph of Clostridium tetani, a Gram positive, spore-forming, anaerobic bacillus.

In our patient the entry was a pressure ulcer. Clostridia can proliferate in such lesions even if there is only a small border of necrotic tissue. Some confounding factors hindered early diagnosis. Her mental state was impaired by dementia, hypoxaemia secondary to pneumonia, and sepsis, so her intermittent abnormal posturing in the context of disorientation and drowsiness suggested the more common diagnosis of meningitis. The rigidity might have been interpreted as a terminal manifestation of dementia, but its extensor character, sudden exacerbations in response to stimuli, and subacute onset pointed towards the diagnosis of tetanus, further supported by the improvement following immunoglobulin treatment.