An update on tetanus Clinical features

CLINICAL FEATURES  The incubation period varies from 3 to 21 days, usually about 8 days. In general the further the injury site is from the central nervous system, the longer the incubation period.  The shorter the incubation period, the higher the chance of death. In neonatal tetanus, symptoms usually appear from 4 to 14 days after birth, averaging about 7 days.  The period between the first symptom and the first spasm is referred to as the onset time.

CLINICAL FEATURES  three different forms of tetanus have been described: 1) Local tetanus 2) Cephalic tetanus 3) Generalized tetanus

Local tetanus  Local tetanus is an uncommon form with an incidence of about 2% with manifestations restricted to muscles near the wound.  The incubation period is long and spasms may spread from one limb to the other. These contractions may persist for many weeks before gradually subsiding.  Local tetanus may precede the onset of generalized tetanus, but is generally milder. Only about 1% of cases are fatal.

Cephalic tetanus  is a rare form of the disease, occasionally occurring with otitis media (ear infections) in which C. tetani is present in the flora of the middle ear, or following injuries to the head. There is involvement of the cranial nerves, especially in the facial area.  Facial paralysis and diplopia due to paralysis of the eye muscles are the common findings. The diagnosis may be missed initially but the other symptoms like trismus dysphagia and spasms follow very rapidly in the majority of cases.

generalized tetanus.  The disease usually presents with a descending pattern. The first sign is trismus or lockjaw, followed by stiffness of the neck, difficulty in swallowing, and rigidity of abdominal muscles.  Other symptoms include a temperature rise of 2°- 4°C above normal, sweating, elevated blood pressure, and episodic rapid heart rate.  Spasms may occur frequently and last for several minutes.Spasms continue for 3-4 weeks. Complete recovery may take months.

generalized tetanus.  Spasms with intervening rigidity (being greater in the trunk than the limbs) occur both spontaneously and on stimulation and varies in severity. Arching the trunk - opisthotonus is a feature during the established disease. Periods of apnoea may occur due to spasm of the intercostal muscles and the diaphragm.

generalized tetanus.  Autonomic dysfunction occurs in the more severe cases and sets in a few days after the spasms due to the slower intra axonal transport to the lateral horn cells.  It consists of a basal sympathetic activity characterized by a resting tachycardia and depression of bowel motility and bladder dysfunction.

generalized tetanus.  Episodes of severe sympathetic overactivity (SOA) which includes fluctuating tachycardia, labile hypertension, sweating and pyrexia takes place both with and without stimulation. Profuse salivation and bronchial secretions due to increased parasympathetic activity also occur. All these signs do not necessarily occur concurrently and its severity varies from patient to patient.

generalized tetanus.  Episodes of bradycardia and hypotension some times lead to cardiac arrest, These signs have been explained on the basis of increased parasympathetic activity, but many attribute it to sudden withdrawal of sympathetic activity as the bradycardia does not always respond to atropine. Cardiac arrest in tetanus has also been attributed to myocardial damage caused by high catecholamine levels and toxic damage to the brainstem.

Neonatal tetanus  is a form of generalized tetanus that occurs in newborn infants. Neonatal tetanus occurs in infants born without protective passive immunity, because the mother is not immune.  It usually occurs through infection of the unhealed umbilical stump, particularly when the stump is cut with an unsterile instrument.  Neonatal tetanus is common in some developing countries (estimated >270,000 deaths worldwide per year)

Neonatal tetanus  Neonatal tetanus presents most often about the seventh day of life with a short history of failure to feed. Spasms are typical but the diagnosis can be mistaken for meningitis or sepsis.

Classification &clinical grading  A useful method of grading the severity of tetanus for the purposes of management and study was devised by Ablett  Ablett classified the disease into the following grades: 1)Grade I (Mild) :trismus 2)Grade II (Moderate) :Muscle rigidity (trismus, dysphagia, risus sardonicus neck rigidity, opisthotonus) and fleeting spasms not embarrassing respiration 3)Grade III a (Severe) :Muscle rigidity and severe spasms 4)Grade IIIb (Very severe) :Muscle rigidity, severe spasms and autonomic dysfunction 4)Grade IIIb (Very severe) :Muscle rigidity, severe spasms and autonomic dysfunction

Classification &clinical grading we adopted a modification of Ablett classification which we cosidered to be more useful in the prognosis and management: 1.Grade 1(mild):muscle rigidity affecting one or more group of muscles sparing the muscles of deglutition 2.Grade 2(moderate):muscle rigidity involving the muscles of deglutition 3.Grade3a(severe):musle rigidity and reflex spasms 4.Grade 3b(very severe):autonomic nervous system changes are added

Classification &clinical grading These modifications are justified by the following observations: 1)Muscle rigidity whether localized or generalized has the best prognosis provided that the patient can swallow. Moreover, the more severe forms of disease are usually discharged from hospital with muscle rigidity that will take weeks to disappear. 2)Involvement of the muscles of deglutition adds 2 causes for morbidity (aspiration pneumonia and dehydration) that need special care. 3)All patients with reflex spasms are considered severe because even with infrequent fits, some patients unpredictably develop a shower of fatal spasms.

COMPLICATIONS  Laryngospasm (spasm of the vocal cords) and/or spasm of the muscles of respiration leads to interference with breathing.  Fractures of the spine or long bones may result from sustained contractions and convulsions.  Hyperactivity of the autonomic nervous system may lead to hypertension and/or an abnormal heart rhythm.

COMPLICATIONS  Nosocomial infections are common because of prolonged hospitalization. Secondary infections, which may include sepsis from indwelling catheters, hospital- acquired pneumonias, and decubitus ulcers.  Pulmonary embolism is particularly a problem in drug users and elderly patients.  Aspiration pneumonia is a common late complication of tetanus, found in 50%-70% of autopsied cases.

COMPLICATIONS  J Neurol Neurosurg Psychiatry Oct;74(10): : Brain lesions in the course of generalised tetanus. MRI on the 82nd hospital day revealed cortical and subcortical lesions predominantly in the right frontal and parietal lobes in addition to marked brain atrophy.

COMPLICATIONS  J Anesth. 2000;14(4): Ruptured superior mesenteric artery aneurysms during treatment of tetanus: a case report.

COMPLICATIONS  Mov Disord Oct;18(10): Brainstem myoclonus in generalised tetanus. Electrophysiological studies of stimulus sensitive myoclonus in a man with generalized tetanus revealed features characteristic of hyperekplexia or brainstem myoclonus.

COMPLICATIONS  Acta Orthop Belg Jun;69(3): A case of myositis ossificans as a complication of tetanus treated by surgical excision We report a case of myositis ossificans following tetanus in a female adult patient presenting with ankylosis of both elbows in extension.

Diagnostic tests 1)Spatula test: Apte and Karnad described a simple bedside test to diagnose tetanus: The posterior pharyngeal wall is touched with a spatula and a reflex spasm of the masseters indicates a positive test. This occurred in 349 of the 350 patients with tetanus (sensitivity 94% and in no patient without tetanus (specificity 100%)

Diagnostic tests 2.The altered whistle in tetanus: Eric R Dunn MJA (11/12): 687 The alteration of a person's whistle in tetanus can be explained as an early effect of the increased tone in facial muscles, which causes the classic risus sardonicus.

Differerential diagnosis  Strychnine poisoning  Dental infections  Local infections  Hysteria  Neoplasms  Encephalitis  dystonia