MERPES ZOSTER

MERPES ZOSTER

(Shingles)

DEEINITION

MERPES ZOSTER is an acute infection involving the first sensory neurone of various nerves with appearance of vesticles in the sensory distribution over the skin and mucous membrane caused by Zoster varicella virus.

AETIOLOGY

The causative organism is a virus which is said to be identical or closely related to the virus of chicken pox. This is a recrudescence of infection of varicella zoster virus which remains in a latent state in the dorsal root ganglion. The virus affectes the posterior root ganglia.

The disease may be precipitated by injury, spinal metastasis from carcinoma, Hodgkin’s disease, from irritation of meninges as in meningitis, subarachnoid haemorrhage or with immunosuppression by various diseases (particularly HIV infection) and drugs (steroids). In such cases the disease is severe in type and widespread.

Incubation Period

About 15 days.

CLINICAL FEATURES

Age: Common in adults and middle aged persons. General symptoms include fever, malaise, lymphadenopathy, etc. which may precede the deveopment of pain. The first specific symptom is pain in the segmental distribution of the nerves involved which is burning, shooting or cutting in character associated with hyperaesthesia or hyperalgesia over the affected cutaneous segments. Within a few days (3-4 days), this is followed by appearance erythema initially and later on papules, vesicles or bullous lesions containing clear fluid inside. Ultimately pustules are formed. The lesions consist of tense, deep-seated grouped vesicles distributed unilaterally along with the nerve pathway of the trunk, over the skin outside the affected dermatome. Minimum 20 vesicles may be present. Local lymph nodes may be enlarged and tender. These eruptions are distributed over the cutaneous segments of the affected nerves. A single unilateral dermatone is usually involved. Thoracic or lumber roots are commonly affected and rarely the cervical root and trigeminal nerve. Visceral involvement is not seen, but due to involvement of nerves, visceral symptoms may develop, e.g. when sacral nerves are affected bladder symptoms may develop. So long the vesicles are present the pain remains very severe. In course of time after 5-7 days the vesicles are dried up leaving behind permanent scars on the skin. Some patients may develop post- herpetic neuralgia (10%) with intractable pain after the vesicles are dried up even after one months of appearance of vesicles. This is particularly common (60%-70% ) in subjects above 60 years. With rare exception more than one attack does not occur in one’s life time. Dermatomal Herpes does not indicate underlying malignancy but when it is generalised, it may indicate presence of immunosuppressive disorder, e.g. AIDS or Hodgkin’ lymphoma. Development of Herpes in HIV infected persons indicates marked depression of cellular immunity…| MERPES ZOSTER

TYPES

Zoster of the limbs and trunk

This is the usual type seen where the posterior root ganglia of

the spinal nerves are involved.

Ophthalmic Zoster or Gasserian Herpes

This involves the ophthalmic division of the 5th cranial nerve and hence eruptions may appear on the cornea and nasal mucous membrane. It may lead to blindness.

Geniculate Zoster

Described in Facial nerve (Ramsay-Hunt Syndrome).

Generalised Zoster

In rare cases there may be scattered eruptions throughout the body.

Zoster encephalitis, Myelitis and Meningitis

In all cases of Herpes Zoster some amount of meningeal irritation is usually seen in the form of increased protein and cells in CSF but true meningitis may also occur with its clinical signs. Infection may extend into the brain and spinal cord giving rise to encephalitis or myelitis with evidences of involvement of pyramidal tract.

COMPLICATIONS

1. Neuralgia.

2. Anaesthesia.

3. Scarring.

4. Paralysis.

5. Encephalitis.

6. Post-herpetic neuralgia.

7. Blindness after ophthalmic Herpes.

8. Disseminated Herpes.

TREATMENT OF MERPES ZOSTER

1. General treatment includes dry dressing and dusting of Povidone iodine or Hexachlorophene powder over the eruptions. In ophthalmic zoster antibiotic drops may be required to prevent secondary infection. Drying solution, e.g. Calamine cream or lotion may be used. In compromised patients Idoxuridine 20 % to 40 % in Dimethyl sulphoxide (DMSO) may be applied over the affected dermatome. Acyclovir 400-800 mg orally 4-5 times a day for about 7 days is said to be the treatment of choice. It may reduce acute pain if started within 2-3 days of onset. The same drug in the cream form may also be used locally. Famciclovir 500 mg 3 times daily is a recent drug. It is useful when Acyclovir cannot be used.

2. For relief of pain, analgesic drugs, e.g. Aspirin, Paracetamol etc. may be used. Morphine or pethidine are usually avoided for fear of habit formation. Pituitrin 1 ce IM, Vitamin B, 100 mg, Vitamin B12 100 ug IM, Griesovin or Steroids are said to give dramatic relief of pain in some cases but results are not uniform. Topical Capsaicin (0.025%) is also helpful in 50% of cases. Deep X-ray therapy over the spinal cord, nerve roots or ganglia may also be given. For post-Herpetic neuralgia Carbamazepine or Phenytoin may be tried. If this fails ablation of appropriate ganglia may also be done. Adenine arabinoside and Zoster immune globulin are also said to give beneficial results.

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