Page 310 - Medicine and Surgery

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306 Chapter 7: Nervous system

Clinical features Large doses of diazepam may be needed to reduce
The incubation period can be days to weeks and the spasms and cardiovascular instability is controlled with
wound may be so slight as to be unnoticed. β blockers. Tracheostomy and ventilatory support may
Generalisedtetanusisthemostcommonpresentation, be necessary for severe laryngeal spasm.

withlockjaw(trismus),causedbymasseterspasm.The Childrenareroutinelyvaccinatedagainsttetanusfrom
facial muscles may contort to cause a typical expres- age 2 months.
sion (risus sardonicus). Any sensory stimulation such
asnoiseresultsingeneralisedmusclespasmsincluding Poliomyelitis
arching of the back (opisthotonos). Spasms of the lar-
ynx can impede respiration, and autonomic dysfunc- Definition
tion causes arrhythmias, sweating and a labile blood Infection of a susceptible individual with poliovirus type
pressure. 1, 2 or 3, which can lead to a mild meningitic illness with
Localised tetanus can occur around the contaminated acute paralysis and subsequently post-polio syndrome.

wound, full recovery is usual.
Cephalic tetanus is uncommon but invariably fatal. It Age

occurs when C. tetani is inoculated from the middle Mainly a disease of childhood.
ear.

Sex
Investigations No sexual preponderance.
The diagnosis is essentially clinical, bacteria are rarely
isolated. Geography
Acute poliomyelitis has been eradicated in developed
Complications countries, apart from rare cases due to the live, atten-
Muscle spasms may lead to injury, in severe cases res- uated oral polio vaccine. Serotype 2 has been completely
piratory failure, cardiac arrest or aspiration leading to eradicated worldwide (announced by WHO in 1999).
death.
Aetiology
Poliovirus is a ssRNA, non-encapsulated, icosahedral
Management
virus 25–30 nm in size. It is an enterovirus, i.e. it spreads
Following contaminated injury patients require with
by the faeco–oral route.
early wound debridement and the administration of hu-
man tetanus immune globulin (passive immunisation)
if their immunisation status is unknown or they have not Pathophysiology
had a booster in the last 5 years. Thevirusisneurotropic,withpropensityfortheanterior
A booster dose with tetanus toxoid (which is an in-
horn cells of the spinal cord and cranial nerve motor
activated toxin which induces active immunisation), neurones. The virus enters via the gastrointestinal tract,
or course of three injections, should additionally be then migrates up peripheral nerves.
given, as the protection from antitetanus immune
globulin only lasts 2 weeks. Antibiotics may also be Clinical features
indicated. Theincubationperiodis7–14days,anumberofpatterns
Active tetanus:Patients should be nursed in a quiet, occur:
dark area to reduce spasms. Surgical wound debride- Subclinical infection occurs in 95% of infected indi-
ment should be performed where indicated and intra- viduals.
venous penicillin and high doses of human tetanus im- Acute polio presents with a mild self-limiting fever
mune globulin should be given i.m. (some around the with or without meningism.
wound). However, the immunoglobulin can only neu- Paralytic poliomyelitis occurs in about 0.1% of in-
tralise circulating toxin, it has no affect on bound toxin. dividuals. This form is predisposed to by male sex;