While tetanus cases have significantly decreased in developed nations due to effective vaccination programmes, the situation is reversed in developing countries.^4,9 In developing countries, it is considered a public health hazard.⁴ Although treatable, tetanus can cause severe complications to various body systems that could result in death. Some of these complications can be more deadly than others. This is no surprise, as Clostridium tetani produces a toxin that is known as the most potent neurotoxin after botulism, with a lethal dose of 2.5 ng/kg.⁵ 

Understanding tetanus and its complications

Overview

What is tetanus?

Tetanus, commonly called Lockjaw because of its characteristic symptom of jaw muscle cramping,  is a sudden infectious disease caused by the spores of Clostridium tetani.  Although the natural habitat of this bacterium is the soil, it can be found in the stools of humans and animals.^1,3 As well as the skin, rusty tools like nails, barbed wire, and needles. The bacteria spores can withstand high temperatures and antiseptic use and can survive for 2 years. However, an effective way to kill the spore is by autoclaving at 1 atmosphere pressure at 120 °C for 15 minutes.¹

How does tetanus occur?

For tetanus to manifest, a wound is usually present. This wound allows the spores to have access inside the body when it comes into contact with the soil, rusty materials, or manure. When this occurs, this wound is no longer a simple injury but now a tetanus wound. Once infected, these spores secrete two neurotoxins: tetanospasmin and tetanolysin.¹ However, only one, tetanolysin, can cause local tissue damage and provide an environment for bacterial multiplication. While the other toxin, tetanospasmin, causes clinical symptoms of tetanus to manifest.¹ After the toxins are released, a clinical triad of muscle spasms and rigidity occurs, followed by the onset of early symptoms within an incubation period of 3-21 days.¹ These symptoms include:¹

• Neck stiffness 
• Sore throat 
• Difficulty opening the mouth
• Jaw cramping 

Types of tetanus 

There are different types of tetanus, such as:⁷ 

• Generalised Tetanus: Affecting all the body's muscles 
• Localised Tetanus: Only affecting a particular area 
• Cephalic Tetanus: Tetanus occurring due to head wounds 
• Neonatorum Tetanus: Tetanus occurs in newborns due to the use of non-sterile equipment in procedures such as umbilical cord care 

What are the complications related to tetanus?

Tetanus complication arises due to its clinical triad of symptoms, namely muscle spasms and autonomic dysfunction.⁷ As well, complications can also be due to the long duration of critical care needed for the condition, given its fatal and critical nature.⁷ Regardless of specific treatment to help complications, the best way to reduce the fatality of the disease is to prevent said complications.⁸ 

These complications have the potential to affect the following systems:⁷

• Respiratory 
• Cardiovascular 
• Gastrointestinal 
• Musculoskeletal
• Renal

Other complications that occur are:⁷

• Sepsis 
• Multiple organ failure 

What are the risk factors for tetanus complications?

Potential risk factors for tetanus complications include:¹²

• Lack of tetanus immunisation
• Diabetes
• History of immunosuppression 
• Intravenous drug use

Other complications are:

• Delayed medical treatment 
• Untreated wounds 

Respiratory complications

Respiratory complications are potential damage to the respiratory system associated with tetanus. They often occur early and require aggressive airway management, such as tracheostomy.⁷ These system complications arise because of the clinical triad: muscle spasms, pulmonary infections, atelectasis, and complications related to tracheostomy.^1,4 Muscle spasms that are convulsion-like in appearance can lead to respiratory failure if continuous, and in the case of pharyngeal and laryngeal spasms, aspiration and fatal sudden airway blockage could be the issue, as difficulty breathing will set in, leading to hypoxia.

Pulmonary infection arises as a result of the following organisms:⁴

• Klebsiella sp
• Pseudomonas aeruginosa 
• Enterobacter sp
• Pneumococcus
• Staphylococcus 

Although most of the infection can be treated with appropriate antibiotic therapy, it is still responsible for significant mortality and morbidity when it comes to tetanus.⁴ 

Other respiratory complications include:¹

• Apnoea
• Pneumonia
• Acute respiratory distress syndrome 
• Tracheal stenosis. 

Cardiovascular complications

Cardiovascular complications are usually observed in patients with grade III B tetanus and those who have a long duration of intensive care.^4,8 The cause of cardiovascular complications is linked to autonomic system involvement, a result of hyperactivity of the sympathetic nervous system.⁸ This is due to the lack of control of the adrenal gland in releasing catchamine.⁸ 

 Cardiovascular complications were diagnosed based on the presence of:⁹

• Dysautonomia
• Septic shock
• Cardiogenic shock
• Acute pulmonary oedema
• Coronary insufficiency
• Arrhythmias
• Deep venous thrombosis
• Pulmonary embolism
• Stroke
• Pressure ulcers 

Conditions like arrhythmias, episodic hypertension, and persistent hypotension are common cardiovascular complications; however, cardiac arrest was found to be the most common cause of death related to tetanus.^4,10 

Other cardiovascular complications include:¹

• Tachycardia 
• Ischaemia
• Bradycardia 
• Asystole

Autonomic nervous system dysfunction

Autonomic nervous system dysfunction can be fatal, especially in developing countries, as high mortality rates are seen in both adults and neonates.^8,11 Autonomic nervous system dysfunction is caused by the tetanus neurotoxin effect on inhibitory neurons, and it has a poor prognosis in severe tetanus patients.^8,11 As they present with:¹² 

• Autonomic overactivity
• Fluctuating hypertension
• Tachycardia
• Increased secretions 
• Sweating 
• And urinary retention 

Factors that influence this prognosis include:¹¹ 

• Shorter incubation period and onset period
• Tachycardia 
• Fluctuating blood pressure 
• Tetanus due to Intramuscular injection, especially with medications like quinine
• Extreme of age 
• Hypoxia or acidosis on admission

More complications that arise during the recovery process include:⁶,¹²

• Disorientation 
• Emotional liability
• Depression
• Neurological deficits
• Coma
• Seizures

Musculoskeletal complications

Muscle spasms can vary in severity and frequency.¹ These spasms can be strong enough to cause tendon rupture, joint dislocation, and bone fracture.¹² Muscle spasms can also extend to the calf; once they are continuous, permanent contractures can appear if a physiotherapist's attention is not given.⁶ Muscle spasms in other areas, such as the neck and trunk, can lead to risus sardonicus expression and opisthotonus expression, respectively.¹² 

Other complications, like paralysis, may be fully resolved within 2–3 weeks, although it's not the same case for neck stiffness and muscular rigidity, as they can persist for more weeks. ⁶

Gastrointestinal complications 

Autonomic nervous system dysfunction causes gastrointestinal problems such as: ^1,7

• Weight loss
• malnutrition 
• Gastric stasis
• Illeus
• Diarrhoea
• Haemorrhage  

This is because ANS dysfunction causes:⁷

• An increase in metabolic rate due to the fever it brings about.
• Muscular activity paralysis, leading to gastric stasis. 

Renal complications

Renal complications in tetanus usually occur when the cardiovascular complication, hypotension, happens.¹³ This is because there is reduced blood flow to the brain, specifically to the cerebral cortex.¹³ The body therefore compensates for this by reducing blood flow to the kidneys, and this action decreases the glomerular filtration rate.¹³ Although early signs of renal complications in tetanus are altered handling of sodium and water, oliguria and uraemia follow the event of reduced blood flow.¹³

Acute kidney injury is a common renal complication of tetanus and is associated with an increased mortality rate of tetanus.¹⁴ Factors that can cause acute kidney injury are:¹⁴

• ANS dysfunction 
• Rhabdomyolysis 
• Use of nephrotoxic medication
• Sepsis

Renal failure is another complication of tetanus; it is caused by the overactivity of the sympathetic nervous system and has a poor outcome.¹³ There are two types of renal failure associated with tetanus: high-output renal failure and oliguric renal failure.¹² They are caused by:¹²

• Rhabdomyolysis
• Urinary stasis
• Urinary tract infection
• Gastric stasis 
• Ileus
• Haemorrhage

The best prevention of renal failure is the management of sympathetic nervous system overactivity.¹³

Generalised infection: Sepsis 

Sepsis can potentially cause death when it arises in tetanus.¹⁵ It follows the event of acute kidney injury and can also be a result of:¹⁵

• Long periods of recumbency
• Invasive procedures such as the use of urinary and central line catheters, long periods of intubation, and tracheostomies
• Infected wounds

Prevention of tetanus complications

Clostridium tetani is found everywhere, and immunity cannot be acquired by contracting tetanus. The best tactic is to get vaccinated.¹ The tetanus vaccine has been around since 1923, and by 1961, it was available in the United kingdom.¹

Vaccination starts at two months of age; during this time, three injections are given within the space of three months,¹ and then a booster is given at five years old.¹ It is important to go for all three injections, as the second one gives immunity and the third prolongs it.¹ During adulthood, it is advisable to get two boosters spaced 10 years apart and stop by the time the individual is 30 years old.¹

Other preventive measures for tetanus complications include:¹

• Prompt medical attention to wounds 
• Proper care of wounds includes changing the dressing regularly

Summary

Clostridium tetani is a bacterium that causes tetanus, and it is found everywhere. This bacterium releases two neurotoxins that lead to a clinical triad of muscle spasms and rigidity. Tetanus is a condition that can be mild, moderate, or severe, and it can often lead to complications that affect the respiratory, cardiovascular, autonomic, musculoskeletal, gastrointestinal, and renal systems. It can also cause complications like sepsis and multiple organ failure. Most complications of tetanus arise from autonomic nervous system disturbances; however, cardiovascular complications are often more fatal. Therefore, it is important for you to stay vaccinated, perform proper wound care, and receive prompt medical attention for wounds.