Hey – I just met you, and this is crazy, but you’ve got Tetanus, so take this Ig

Hey – I just met you, and this is crazy, but you’ve got Tetanus, so take this Ig
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A 65 year old male presents to the Emergency Department with a 3-day history of worsening, painful stiff neck.

He reports that he is not able to sleep due to the pain and has seemingly very limited ROM of his neck from the end of the bed.

He also reports night sweats, and has a very swollen, red left elbow. He tells you that he had a minor puncture wound to the left elbow 8 days ago from a rose thorn in the garden. He says that actually his elbow seems to be improving (“You should have seen it on Saturday!”), and so he hadn’t thought to trouble a doctor about it.

He is otherwise previously well, takes no regular medications, and works as an academic at the local university.

He says that he had vaccinations as a child (in the USA) and he “got a lot of needles” before a trip to India that was “probably more than 10 years ago”, but as far as he can remember he hasn’t had any vaccinations since then.

On examination:

  • He is alert and oriented, GCS = 15.
  • T = 36.2. HR 68. Sats 97%. BP 128/74.
  • He has normal tone, power and reflexes in all 4 limbs. PEARL. No photophobia. Kernig and Brudzinski negative.
  • On his left elbow there is what seems to be a large bursitis and cellulitis, but he has full ROM of the elbow and reports it is not painful and only minimally tender.
  • There is no tenderness in his neck, and no palpable nodes or other masses.
  • His active ROM of the neck is roughly <30 degrees in all directions. Passive ROM is slightly greater. He has good mouth opening but reports that it feels “tight”. He also comments that he has found it more difficult to swallow in the last 3-4 days – for solids only – and that it sometimes takes several attempts before he is able to get the food down.

[After some quick reading on UpToDate I performed]… The “spatula test”

Believed to be the most reliable clinical sign for tetanus (sensitivity 94%, specificity 100%). This ‘test’ involves touching the posterior pharyngeal wall with spatula (tongue depressor):

  • Positive = involuntary contraction of the jaw (biting down)
  • Negative = gag reflex

In our patient – the spatula test was ….. equivocal! No gag and no biting down on the spatula.

Impression at this point:

  • Cellulitis and bursitis of the left elbow
  • Neck stiffness and swallowing issues
    • ?Collection / lymphadenopathy in neck secondary to infection at elbow

Investigations and initial management

  • FBC + CRP
  • Tetanus serology (anti-tetanus toxoid)*
  • CT neck
  • Tetanus toxoid vaccination
  • Tetanus Immunoglobulin (prophylactic dose)

I decided that given a suspicion of tetanus, and his unclear immunisation history, that I would give a dose of tetanus Ig in addition to vaccination. The prophylactic dose is 500 units (treatment dose 3000 to 6000 units).

*This is not a very useful test and is not recommended. Will only be positive in about 30% of clinically diagnosed cases. 

The results were as follows:

  • Hb – 146
  • WCC –  9.2
  • Neut – 7.39
  • Na – 140
  • K – 4.1
  • Ur – 6.4
  • Cr – 100
  • CRP – 70

CT Neck

  • “No walled off collection or foreign body identified”

At this point, I felt I had effectively ruled out a lesion within the neck itself, and meningitis seemed unlikely given the presentation. I called the ID consultant on call and referred the patient as a “suspected tetanus”. The ID team came promptly – performed another spatula test – and then admitted the patient with ?Tetanus. He was taken for washout of his elbow under orthopaedics later that afternoon and received IV metronidazole and a cephalosporin.

He had a subsequent MRI brain and neck which were also unremarkable. His symptoms slowly improved and after an otherwise uneventful stay in hospital he was discharged after several days.

A bit about tetanus

Read the full Tetanus article here.

Summary

  • Caused by tetanus toxin, produced by clostridium tetani
  • 10% of cases are fatal
  • The toxin is so potent, that it does not cause an immune reaction, and those whom have had tetanus are not usually immune to future infection
  • Most cases are in previously unvaccinated individuals
  • Most common in >65 age group
  • Most dangerous in neonates

Infection

  • Clostridium tetani is found in soil and animal faeces
  • Penetrating wounds – i.e. puncture wounds (the above patient’s rose thorn) – are associated with higher risk
  • It is often associated with co-infection with another organism – clostridium tetani typically needs dead / necrotic / ischaemic tissue to thrive
  • Clostridium tetani bacteraemia and sepsis are rare
  • Incubation period can be from 3-28 days – and depends on the site of infection – the toxin travels up to peripheral nerves to the brain – the longer the distance – the longer it takes to reach the brain. Infection sites on the head and neck have short incubation and on the limbs it can be weeks

Mechanism

  • Affects motor neurons
  • In the brainstem, it irreversibly binds at synapse to prevent release of neurotransmitters – particularly those involved with inhibition
  • New synapses form but this process can take up to 8 weeks – as such duration of symptoms is typically 6-8 weeks

Presentation

  • Prodrome: fever, malaise, headache
  • Trismus
  • Neck stiffness
  • Dysphagia
  • Risus sardonicus (grinding expression of facial muscles)
  • Opisthotonus (arching of body with neck hyper-extension)
  • Spasms – initially induced by movement/noise but later spontaneous
    • Muscle spasms can be so severe that they cause long bones to fracture
  • Autonomic dysfuction (arrhythmias and BP fluctuations)
  • Rigid board abdomen

Signs and symptoms can continue to progress for up two weeks after presentation, and can be variable, depending on the amount of toxin that reaches the CNS. Some studies have also suggested that the severity of symptoms is correlated to the previous level of vaccination – those with more up to date vaccination suffer less severe disease.

Symptoms can last for 4-8 weeks.

Death is due to respiratory arrest.

Management

Good quality published evidence for many of these interventions is lacking

  • Clean and debride the wound
  • Metronidazole (clears the bacteria but has no effect on toxin already produced)
    • If adequate wound debridement has not occurred, re-infection from spores in the wound can occur
    • IV 500mg TDS
    • Often a mixed infection is present – consider empirical antibiotic therapy for cellulitis +/- wound swabs for directed antimicrobial therapy
  • Tetanus immunoglobulin IM/IV
    • 3000 – 6000 units recommended
    • This neutralises the unbound toxin, but has no effect on the toxin that has already bound to synapses
  • Give a tetanus vaccine – e.g. DTaP
  • Diazepam/magnesium- to control muscle spasms
    • High doses – typical doses might include diazepam IV 10-30mg Q1H, maximum daily dose of 500mg
    • Continuous infusion of midazolam may be considered
  • In severe cases – neuromuscular blockade and I+V
    • May be required for 6-8 weeks!
    • Nutritional demands are often very high due to prolonged muscle contractions. PEG feeding plus TPN might be required
  • Control the autonomic dysfunction
    • Magnesium sulphate, often in combination with beta-blocker (often an IV infusion of labetolol) and morphine have been used

Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) currently works as a GP Registrar and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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