Tetanus

Tetanus

• Tetanos – a greek word – to strech

• First described by Hippocrates & Susruta

• A Neurological disease characterised by increased muscle tone & spasms.

• Caused by CLOSTRIDIUM TETANI

• An anaerobic, motile, gram positive rod that forms oval, colourless, terminal spores –tennis racket or drumstick shape.

• It is found worldwide in soil, in inanimate environment, in animal faeces & occasionally human faeces.

Epidemiology

• Occurs sporadically

• Affects unimmunized, partially immunized & fully immunized who fail to maintain adequate immunity with booster doses of vaccine.

• Although it is an entirely preventable disease by immunization , the burden of disease worldwide is great.

• As reporting is inaccurate & incomplete, particularly in devoleping countries, W.H.O considers reported cases to be an underestimate & takes case/death estimates to assess the burden of disease.

• In 2002, the estimated deaths in all age groups 2,13,000of which 1,80,000 were attributable to neonatal tetanus.

• More common in areas where soil is cultivated, in rural areas, in warm climates, during summer, among males.

Pathogenesis

• Contamination of wounds with spores of C.tetani.

• Germination & toxin production – in wounds with low oxidation – reduction potential ( devitalized tissues, F.B, active infection )

• Tetanospasmin ( neurotoxin )

• Tetanolysin ( hemolysin )

• Tetanospasmin ( exotoxin ) produced locally , released into bloodstream .

• Binds to peripheral motor neuron terminals & nerve cells of ant.horn of spinal cord

• The toxin after entering axon , transported to nerve cell body in brain stem & spinal cord – retrograde intraneuronal transport

• Toxin – migrates across synapse – presynaptic terminals- blocks the release of Glycine & GABA from vesicles.

• The blocking of neurotransmitter release by Tetanospasmin involves cleavage ofSynaptobrevin – essential for proper fn of synaptic vesicle release apparatus

• With diminished inhibition – resting firing rate of alpha motor neurons increases – rigidity

• Lessened activity of reflexes which limit polysynaptic spread of impulses, agonists & antagonists recruited - spasms

• Loss of inhibition of preganglionic sym neurons – sympathetic hyperactivity

Mode of transmission

• Infection is acquired by contamination of wounds with tetanus spores.

• Range of injuries & accidents – trivial pin prick, skin abrasion, puncture wounds, burns, human bites, animal bites & stings, unsterile surgery, IUD, bowel surgery, dental extractions, injections, unsterile division of umbilical cord, compound #, otitis media, chr.skin ulcers, eye infections, gangrene

• NOT TRANSMITTED FROM PERSON TO PERSON

Types

• Traumatic

• Puerperal

• Otogenic

• Idiopathic

• Tetanus neonatorum

PARK 19th

• Generalized

• Neonatal

• local

HARRISON 17th

Clinical features

• May begin from 2 days to several weeks after the

injury – USUALLY 1 WEEK

• Remember

Shorter the incubation period

More severe the attack

Worse the prognosis

Clinical features

• GENERALIZED TETANUS• Most common• Increased muscle tone & generalized spasms• Median time of onset after injury – 7 days• Pt 1st notices increased tone in masseter

( Trismus, lock jaw )• Dysphagia • Stiffness / pain in neck, shoulder, back muscles

appear concurrently / or soon thereafter• Rigid abd & stiff prox.limb muscles . Hands, feet

spared.

trismus

• Risus Sardonicus : Spasm of facial muscles ( frontalis & angle of mouth muscles ) producing grinning facies

• Opisthotonus : Painful spasms of neck, trunk and extremity. producing characteristic bowing and arching of back

• Some pts devolep paroxysmal, violent, painful, generalized muscle spasms – cyanosis . Spasms occur repetitively & may be spontaneous / provoked by slightest stimulation.

• Constant threat during gen.spasm is reduced ventilation, apnea / laryngospasm.

Risus sardonicus

• Mild ds ( muscle rigidity , no / few spasms )

• Moderate ds (trismus, dysphagia, rigidity, spasm)

• Severe ds ( freq explosive paroxysms )

• Autonomic dysfn complicates severe cases -labile htn, hyperpyrexia, profuse sweating, peripheral vasoconstriction, raised catecholamines.

Neonatal Tetanus

• Usually fatal if untreated

• Children born to inadequately immunized mothers, after unsterile treatment of umbilical stump

• During first 2 weeks of life.

• Poor feeding ,rigidity and spasms

Local Tetanus

• Uncommon form

• Manifestations are restricted to muscles near the wound.

• Cramping and twisting in skeletal muscles

surrounding the wound – local rigidity

• Prognosis – excellent

Cephalic Tetanus

• A rare form of local tetanus

• Follows head injury / ear infection

• Involves one / more facial cranial nerves

• Trismus and localised paralysis ,usually facial nerve, often unilateral.

• Incubation period : few days

• Mortality : high

Diagnosis

• Based entirely on clinical findings• Examine all cases with wound infection & muscle

stiffness• Wound cultures – in suspected cases

C.tetani can be isolated from wounds of pts without tetanus & freq cannot be isolated from wounds of those with tetanus

• Electromyograms – continous discharge of motor units, shortening / absence of silent interval seen after AP.

• Muscle enzymes – raised

• Serum Anti toxin levels >= 0.1 IU/ml –protective & makes tetanus unlikely .

Differential diagnosis

• Cond producing trismus : alveolar abscess, strychnine poisoning, dystonic drug reactions, hypocalemic tetany

• Meningitis/encephalitis

• Marked increased tone in central muscles , with superimposed generalized spasms & relative sparing of hands & feet – sugg tetanus

Treatment – general measures

• Goal is to eliminate the source of toxin, neutralize the unbound toxin & prevent muscle spasm & providing support - resp support

• Admit in a quiet room in ICU • Continuous careful observation &

cardiopulmonary monitoring• Minimize stimulation• Protect airway• Explore wounds – debridement

• NEUTRALIZE TOXIN :

• Inj.Human Tetanus Immunoglobulin 3000 – 6000 units IM, usually in divided doses as volume is large.

ANTIBIOTIC THERAPY :

• Although of unproven value , antibiotics adm to eradicate vegetative cells – the source of toxin

• IV Penicillin 10 -12 million units daily for 10 days

• IV Metronidazole 500mg Q 6 hrly / 1gm Q 12 hrly

• Allergic to Penicillin : consider Clindamycin & Erythromycin

Control of Spasms

• Nurse in a quiet dark room

• Avoid noise & other stimuli

• IV Diazepam / Lorazepam / Midazolam

• Barbiturates & Chlorpromazine –2nd line drugs

• Continued spasms : intubate & ventilate

• Propofol, dantrolene, intrathecal baclofen, succinylcholine & magnesium sulfate can be tried

Management of autonomic dysfn

• Labetalol

• Continuous infusion of esmolol

• Clonidine / verapamil

Additional measures

• Pts recovering from tetanus should be actively immunized

• Hydration

• Nutrition

• Physiotherapy

• Prophylactic anticoagulation

• Bowel, bladder, back care

• Treatment of intercurrent infection

Prevention – Active Immunization

• For partially immunized, unimmunized and

recovering from tetanus

• It stimulates production of protective antitoxin

• 2 prep : combined vaccine : DPT

monovalent vaccine : plain / formol

toxoid

tetanus vaccine , adsorbed

Combined vaccine

• According to National Immunization, 3 doses of DPT – at intervals of 4-8 wks, starting at 6 wks age, followed by

• booster at 18 months age

• 2nd booster (only DT) at 5-6 yrs

• 3rd booster ( only TT) after 10 yrs age

Monovalent vaccines

• Purified tetanus toxoid ( adsorbed ) supplanted the palin toxoid – higher & long lasting immunity response

• Primary course of immunization – 2 doses • Each 0.5 ml , injected into arm given at intervals of 1-

2 months• The longer the interval b/w two doses, better is the

immune response• 1st booster – 1 yr after the initial 2 doses• 2nd Booster : 5 yrs after the 1st booster ( optional )• Freq boosters to be avoided

Passive immunization

• Temp protection – human tetanus immunoglobulin /ATS

• Human Tetanus Hyperimmunoglobulin :

• 250-500 IU

• Does not cause serum sickness

• Longer passive protection compared to horse ATS( 30 days / 7 -10 days )

Passive immunization

• ATS ( EQUINE ) :

• 1500 IU s/c after sensitivity testing

• 7 – 10 days

• High risk of serum sickness

• It stimulates formation of antibodies to it , hence a person who has once received ATS tends to rapidly eliminate subsequent doses.

Active & Passive Immunization

• In non immunized persons

• 1500 IU of ATS / 250-500 units of Human Ig in one arm & 0.5 ml of adsorbed tetanus toxoid into other arm /gluteal region

• 6 wks later, 0.5 ml of tetanus toxoid

• 1 yr later , 0.5 ml of tetanus toxoid

Prevention of neonatal tetanus

• Clean delivery practices• 3 cleans : clean hands, clean delivery surface,

clean cord care• Tetanus toxoid protects both mother & child• Unimmunized pregnant women : 2 doses

tetanus toxoid• 1st dose as early as possible during pregnancy• 2nd dose – at least a month later / 3 wks

before delivery

• Immunized pregnant women : a booster is sufficient

• No need of booster in every consecutive pregnancy

Prevention of tetanus after injury

• All wounds should be thoroughly cleaned soon after injury

• Remove all foreign bodies, soil, dust, necrotic tissue

A – completed course of toxoid/booster < 5 yrs ago

B- completed course of toxoid / booster >5 yrs ago & < 10 yrs ago

C- completed course of toxoid / booster >10 yrs ago

D- not completed course of toxoid / immunity status unknown

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