Herpes zoster oticus

There are three separate neurological Ramsay Hunt syndromes. Their only connection is James Ramsay Hunt who identified them all:

• Ramsay Hunt syndrome (herpes zoster oticus or auricular herpes zoster) - described here.

• Ramsay Hunt cerebellar syndrome (dyssynergia cerebellaris myoclonica, dyssynergia cerebellaris progressiva, dentatorubral degeneration) is the rare entity characterised by seizures, cognitive impairment, action myoclonus and progressive ataxia.

• Ramsay Hunt syndrome III is a neuropathy of the deep palmar branch of the ulnar nerve.

The Ramsay Hunt syndrome described here occurs when the varicella-zoster virus (chickenpox) becomes reactivated in the geniculate ganglion of the VIIth cranial nerve (facial nerve) causing facial paralysis, loss of taste, vestibulocochlear dysfunction and pain. See the separate Shingles and Shingles Vaccination article for more information on herpes zoster.

As a general rule, shingles is a disease of sensory nerves but Ramsay Hunt syndrome is distinctive in that there is a motor component. J. Ramsay Hunt described the various clinical presentations of facial paralysis with a rash and also recognised other frequent symptoms and signs such as tinnitus, hearing loss, nausea, vomiting, vertigo and nystagmus.

Functional anatomy

The neuroanatomy involved in Ramsay Hunt syndrome is more complex than cases of shingles of a single dermatome elsewhere in the body.

There are four cranial nerve nuclei involved in facial nerve functions. They are the motor nucleus of VII, the nucleus of the solitary tract, the superior salivatory nucleus and the spinal nucleus of V.

Motor nucleus of VII - special visceral efferent motor fibres from the motor nucleus of VII leave the brainstem and travel through the internal acoustic meatus to the bony facial canal to supply facial muscles. In Ramsay Hunt syndrome, these fibres are affected as they pass through the geniculate ganglion, impairing motor supply of the facial nerve.

Nucleus of the solitary tract - the solitary tract receives special visceral afferent taste fibres from the anterior two thirds of the tongue. These fibres travel with the chorda tympani. The cell bodies of these special visceral afferent fibres are in the geniculate ganglion which is the site of virus reactivation when vesicles erupt on the tongue. The fibres reach the brainstem via the nervus intermedius and can be affected by local inflammation as they pass through the geniculate ganglion.

Superior salivatory nucleus - special visceral efferent parasympathetic fibres to the lacrimal and salivary glands come from the superior salivatory nucleus, travel in the nervus intermedius and branch at the geniculate ganglion into the greater petrosal and chorda tympani nerves. Decreased lacrimation may result from involvement of these fibres as they branch at the level of the geniculate ganglion. Special visceral efferent sympathetic fibres originate from the carotid plexus on the internal carotid artery and join the greater petrosal nerve as they pass through the foramen lacerum. The sympathetic fibres supply the same areas as the parasympathetic fibres.

Spinal nucleus of V - this receives general somatic afferent fibres from the geniculate zone of the ear via the chorda tympani. Cell bodies of these neurons lie in the geniculate ganglia and are the site of viral reactivation in classic Ramsay Hunt syndrome, causing vesicular eruptions in geniculate zones.

Epidemiology

• Herpes zoster is seen as a disease of older people (most commonly over 60 years old)¹. However, it can affect all ages, although is rare in children. There has been a case report of varicella infection in utero and presentation in infancy with this syndrome².

• The incidence and severity increase with age. In one study, about 50% of cases were aged 60 or older³. This is due to a decline in cellular mediated rather than humoral immunity, which is thought to be an effect of ageing⁴.

• The overall incidence of all types of herpes zoster is estimated to be 3.6 cases per 1,000 person-years. However, the increased incidence with age is apparent in the following annual figures³:
  

  • Age under 50 years - 2.0 cases per 1,000 persons.

  • Age 50 to 60 years - 5.0 cases per 1,000 persons.

  • Age 60 to 70 years - 7.0 cases per 1,000 persons.

  • Age 70 to 80 years - 10.0 cases per 1,000 persons.

  • Age over 80 years - 12.0 cases per 1,000 persons.

• About 30% of people will have shingles at some stage in their lives.

• Facial nerve involvement occurs in only 1% of patients, and predominantly affects women in their fifth and sixth decades⁵.

People who are immunocompromised are much more susceptible to shingles in all forms. It tends to be more severe and may present at a comparatively young age. If shingles affects more than one dermatome, immunocompromise such as HIV should be suspected.

Presentation

Symptoms

The presenting feature is often pain deep within the ear. It may be paroxysmal at first but, after a day or two, the pain often radiates outward into the pinna and there is a more constant, diffuse and dull background pain.

The following may also be presenting features:

• Vertigo and ipsilateral hearing loss or hyperacusis.

• Tinnitus.

• Facial weakness or face drop.

• Rash or blisters, which may be on the skin of the ear canal, auricle or both, and may become infected secondarily, causing cellulitis.

Signs

• A rash or herpetic blisters in the distribution of the nervus intermedius.

• The distribution of the rash varies, as does the area innervated by the nervus intermedius. It may include the following:
  

  • The anterior two thirds of one side of the tongue.

  • The soft palate.

  • The external auditory canal, visible only with an otoscope.

  • The pinna.

• An ipsilateral facial drop or weakness may be obvious or it may only be elicited on testing.

• There may be hyperacusis on the affected side, due to paralysis of the stapedius and tensor tympani.

• The patient may have associated ipsilateral hearing loss and balance problems.

The weakness of the facial nerve will show a lower motor neurone pattern as with Bell's palsy. Ask the patient to give a big grin showing their teeth. Ask them to screw up their eyes. Ask them to raise their eyebrows. The upper motor neurone (UMN) innervation of the forehead is bilateral, so that in an UMN lesion of the face, the muscles of the forehead are spared.

Differential diagnosis

• The unilateral facial weakness is very similar to Bell's palsy but neither pain nor a rash occurs with Bell's palsy.

• A rash is not always present (herpes zoster sine herpete), when the diagnosis can only be confirmed by virological testing⁶.

• If vertigo is present, consider viral labyrinthitis or a stroke of the posterior inferior cerebellar artery region.

• Trigeminal neuralgia is paroxysmal and tends to be precipitated by a stimulus such as a cold wind or washing the face.

• Other conditions include:

  • Postherpetic neuralgia.

  • Persistent idiopathic facial pain.

  • Temporomandibular disorders.

  • Otitis (externa or media).

  • Referred pain (eg, dental abscess).

  • Carcinoma of the nasopharynx.

Investigations

• Virological studies, both serological and molecular, are available but usually the diagnosis is clinical.

• Audiometry may be performed.

• Occasionally, nerve conduction studies may be done to determine the extent of damage to the facial nerve and potential for recovery.

• MRI of the internal auditory canal may be useful in atypical presentations⁷.

Associated diseases

Beware of possible immune compromise; an HIV test may be indicated and should be performed in severe cases or if more than one dermatome is affected.

Management

The management of herpes zoster is discussed in the separate Shingles and Shingles Vaccination article, including when it is appropriate to use antiviral agents to reduce the risk of postherpetic neuralgia. The relative merits of adding corticosteroids to antivirals are also discussed there.

In essence, although prompt treatment (within 72 hours) has been shown to be beneficial in patients with shingles, there is a paucity of data regarding the efficacy in Ramsay Hunt syndrome both of:

• Specific antivirals⁸.

• The role of steroids¹.

However, prompt combination treatment is nevertheless recommended, to improve the remission of facial paresis and hearing loss⁹.

A proportion of patients clinically diagnosed with 'Bell's palsy' have Ramsay Hunt syndrome without a rash (herpes zoster sine herpete). Treatment of these patients with aciclovir and prednisolone within seven days of onset has been shown to improve the outcome for recovery from facial palsy. In view of this occurrence, a case can be made for adding antivirals to the treatment of such apparent cases of Bell's palsy. The latter is otherwise thought to be caused by herpes simplex. The number of patients with peripheral facial nerve palsy who, following serological and PCR studies, have herpes zoster sine herpete appears to be small but varies between series from 8-28%¹⁰.

If there is problem with closing the eye, a pad will protect the cornea, and eye lubricants should be prescribed.

Complications

• If closure of the eye is compromised, abrasions may occur.

• Lesions may acquire secondary bacterial infection.

• Postherpetic neuralgia may occur.

• Chronic tinnitus.

• Chronic vestibular dysfunction.

Prognosis

• Early diagnosis and initiation of treatment within 72 hours of the onset of symptoms improve outcome¹.

• The rash will resolve but, unlike Bell's palsy, the rate of complete recovery of facial function is only 75%, even if treatment was initiated within three days, especially if aged over 50 and in the presence of complete paralysis¹.

• Scarring of deep lesions may occur.

• Presence of vertigo is a poor prognostic feature¹¹.

• Hearing loss usually recovers well, with only 5% having residual problems¹.

• Age, diabetes and hypertension appear to be poor prognostic features¹¹.

Historical aspects

James Ramsay Hunt (1872-1937) was born in Philadelphia and graduated MD from the University of Pennsylvania in 1893. After studying in Paris, Vienna and Berlin, he returned to New York to practise neurology at Cornell University Medical School from 1900 to 1910. He described the syndrome that bears his name in 1907¹². His research interests were the anatomy and disorders of the corpus striatum and the extra-pyramidal system. He was consulting physician at several New York hospitals and was appointed professor of neurology at Columbia University College of Physicians and Surgeons, New York, in 1924.