1.Symptoms and signs
Herpes Zoster mainly affects a single dermatome of the skin .
It may occur at any age but the vast majority of patients are more than 50 years of age .
The latent virus reactivates in a sensory ganglion and tracks down the sensory nerve to the appropriate segment .
The lower cervical , thoracic and lumbar posterior root ganglia are most commonly involved . The eruption is commonly preceded by paresthesia , burning pains and tenderness of the skin . The trigeminal ganglion is another common site of reactivation and the ophthalmic branch of this nerve is 20 times more likely to be involved than the 2 other branches .
the sacral ganglia may be involved where it may be associated with retention of urine or sometimes frank haemorrhagic cystitis. Facial palsy associated with vesicles in the external auditory meatus is known as the Ramsay-Hunt syndrome and is though to be a form a zoster involving the VIIth nerve .
It is often accompanied by hearing loss and vertigo. Herpes zoster has also been implicated as acause of bell s palsy without vesicles. As with varicella , herpes zoster in a far greater problem in immunocompromised patient in whom the reactivation occurs earlier in life and second attacks , which are virtually unknown in the immunocomppetent,are frequently seen.
The disease process is likely to be prolonged in the immunocompromised individual and the disseminated form is more likely to be present.Complications of Herpes Zoster
a. Secondary bacterial infection- asin the case of chickenpox, mild secondary infection of the vesicular lesions is common.
b. neuralgia- postherapetic neuralgia is the most common and important complication of herpes zoster. Most patients experience severe constant pain at the site of the lesion but it usually remits within 2 to 3 weeks . However , in some patients , a chronic disabling neuralgia occurs. Most of these patients (80)% improve and recover over one year. In others, the pain is so severe and unremitting that it may lead to suicidal tendencies.
c. Encephalitis - this is a very rare complication of herpes zoster . Other rare CNS manifestations include motor neuropathies , myelitis , Guillain-Barre syndrome and contralateral hemiparesis associated with ophthalmic zoster have been reported .
d. Disseminated herpes zoster - disseminated zoster is much is much more likely to occur in immunocompromised individuals. The patients is likely to be extremely ill, often with visceral involvement but the outcome is rarely fatal.
e. Occular Zoster - the presentation of ophthalmic zoster is complex because many structures of the eye can be involved ie, the eyelid, conjunctiva, cornea and iris. Fortunately, blindness following herpes zoster is rare. Anterior uveitis and kerititis are the most common intraocular complications. Sight threatening complications include neuropathic keratitis, perforation, secondary glaucoma , posterior scleritis, optic neuritis and acute retinal necrosis .