Introduction

Tetanus is a disease that affects the nervous system. It is characterized by muscle spasms due to the tetanospasmin toxin released by Clostridium tetani. C. tetani is an anaerobic bacterium that is commonly found in the soil.

Tetanus-prone wounds

The presence of puncture type wounds, contamination with dirt or manure, sepsis, burns, high-velocity missile injuries, or frostbite increases the risk of tetanus. Also, any wound over six hours old should be considered tetanus-prone.

Trismus

Spasms involving the masseter and temporal muscles may result in trismus, also known as lockjaw, which is an inability to open the mouth. This occurs when C. tetani reaches the spinal cord and brainstem via retrograde axonal transport. Then, the release of tetanospasmin causes defects in the anterior horn inhibition of muscular contraction. The result is involuntary, sustained muscle contraction.

Muscle rigidity

Patients present with prolonged, tonic contraction of involved muscle groups. This occurs due to the inhibition of inhibitory neuromuscular signaling from the anterior horn.

Muscle spasms

Muscle "spasms" are short-lasting muscle contractions. They may be elicited from movements or sensory stimuli. These reflex spasms occur due to hyperactivity of the lower motor neurons due to denervation.

Dysphagia

The involvement of the muscles of the tongue, pharynx, and esophagus can lead to difficulty swallowing. This occurs due to the inhibition of inhibitory neuromuscular signaling from the anterior horn.

Opisthotonus

Patients with generalized tetanus may present with arching of the back due to involvement of the dorsal extensor muscles.

Apnea/upper airway obstruction

Patients may present with shortness of breath due to involvement of the respiratory and laryngeal muscles.

Pain

Pain in tetanus occurs due to severe spasms. Atypically, pain and allodynia can occur due to the involvement of sensory nerves.

Duration

The initial symptoms of tetanus usually occur around ten days after an inoculating trauma. However, the incubation period may range from three days to three weeks.

Localized tetanus

Localized tetanus is a less common form of the disease characterized by spasm of muscles directly adjacent to the wound site. This presentation may precede generalized disease.

Cephalic tetanus

Cephalic tetanus is characterized by trismus, eyelid retraction, dysphagia, deviated gaze, and risus sardonicus. This presentation is caused by involvement of the bulbar musculature.

Risus sardonicus

Patients may present a characteristic facies due to inability to move the facial muscles. It is described as similar to a sardonic, or cynical smile.

Neck stiffness

The involvement of the neck musculature can lead to neck stiffness with reduced range of motion (ROM).

Trismus

Patients with trismus, or lockjaw, will show an inability to open the mouth completely. Repeated attempts to open the mouth can result in more severe trismus. This is due to the involvement of the masseter and temporal muscles.

Opisthotonus

Patients may present arching of the entire back with flexion of the arms and extension of the legs, similar to patients with a decorticate posture. This more common in generalized and neonatal tetanus due to the involvement of the musculature of the back.

Cephalic tetanus

Atypical signs may be present due to less common patterns of neuronal inactivation. This may include nystagmus, vertigo, and diplopia due to the involvement of cranial nerves.

Signs of autonomic dysfunction

Patients may present with hyperpyrexia, increased sweating, hypertension, and tachycardia. Hypotension and bradycardia are also possible. Notable fluctuations of the vital signs may also be seen. This is due to the involvement of the hypothalamic nuclei, brain stem, and autonomic nerves, leading to sympathetic overdrive. Furthermore, excessive acetylcholine release leads to parasympathetic overactivity.

Respiratory distress

Patients may present signs of respiratory distress such as labored breathing, due to the involvement of respiratory and laryngeal muscles.

Neuroleptic malignant syndrome

Neuroleptic malignant syndrome (NMS) can present with muscle rigidity and fever. However, patients classically present with altered mental status and have a history of taking one of the known causative drugs.

Dental infection

A dental infection can lead to trismus and fever. However, rigidity of the other muscle groups will be absent.

Acute dystonic reaction

Acute dystonic reactions present with involuntary muscle contractions and possibly opisthotonus. However, patients with this condition typically have a history of taking a causative drug. They may also demonstrate an oculogyric crisis or torticollis.

Meningitis

Patients with meningitis can present with neck stiffness and fever. However, trismus, risus sardonicus, and opisthotonus are not typical.

Strychnine poisoning

Strychnine poisoning can present with severe muscle contractions, opisthotonus, risus sardonicus, and fever. However, such patients also often have vomiting and convulsions.

Wound debridement

Wound debridement is required to physically remove toxin-producing spores and necrotic tissue and prevent further proliferation of C. tetani.

Benzodiazepines

Benzodiazepines are useful for managing tetanus because of their muscle relaxant, anxiolytic, and sedative effects.

Magnesium sulfate

Continuous infusions of magnesium sulfate may be used to control muscle spasms and autonomic instability, while preventing the need for ventilatory support.

Labetalol

Labetalol may be useful to control the hypertension and tachycardia that occurs due to sympathetic overstimulation.

Intrathecal baclofen

Unlike oral baclofen, which poorly penetrates the blood-brain barrier (BBB), intrathecal baclofen administration has been shown to be effective for controlling severe spasms and reducing the need for ventilatory support. However, this is expensive and some studies show the incomplete resolution of symptoms and a risk of bacterial infection. Therefore, this is not widely practiced.

Ventilatory support

Patients with severe cases may require ventilatory support to prevent fatal respiratory failure.

Neuromuscular blocking agents

Neuromuscular blocking agents can be used to control refractory spasms. Non-depolarizing muscle relaxants, such as vecuronium, rocuronium, and atracurium may be safer than succinylcholine, which can cause hyperkalemia.

Botulinum toxin

The use of botulinum toxin A may be considered for the relief of localized muscle spasms.

Human antitetanus immunoglobulin

Human antitetanus immunoglobulin (HTIg) binds to circulating tetanospasmin before it infiltrates the central nervous system.

Antibiotics

Antibiotic therapy, usually consisting of penicillin G, metronidazole, or doxycycline, may prevent further proliferation of C. tetani from the wound site.

Tetanus vaccine

Any patient with proven tetanus should receive the vaccine since contracting tetanus does not provide subsequent immunity.