Ramsay Hunt syndrome

Ramsay Hunt syndrome (RHS), also known as herpes zoster oticus, is a rare complication that happens when latent varicella zoster virus (VZV) reactivates in the facial nerve (cranial nerve VII).

Pathophysiology

VZV may remain dormant for decades in the geniculate ganglion of the facial nerve or sensory ganglion of the trigeminal nerve (cranial nerve V) following primary infection.

As adaptive immunity decreases as we age and especially in times of physiological stress or an immunocompromised state, the virus can be reactivated following earlier primary infection or VZV vaccination, in the geniculate ganglion, or the trigeminal ganglion, causing facial paralysis, facial pain, and vesicular lesions in a dermatomal pattern. This reactivation leads to inflammation and compression of the facial nerve, especially in the labyrinthine segment. This results in loss of axonal transmission and decreased nerve signal to the muscles of facial expression and subsequent sudden-onset facial palsy.

There are 4 cranial nerve nuclei that are involved in the functions of the facial nerve:

1. Motor nucleus of VII - efferent motor fibres from motor nucleus of VII travel through the internal acoustic meatus to supple the facial muscles. In RHS, these are affected as they pass through the geniculate ganglion which leads to the symptoms of impaired motor function of the facial nerve (dysfunction of the muscles of facial expression).
2. Nucleus of the solitary tract - contains sensory neurons that convey sensation of taste from the anterior 2/3rds of the tongue via the chorda tympani. Their cell bodies are also located in the geniculate ganglion and pass into the brainstem (via the nervous intermedius). It may also be affected when passing through the geniculate ganglion → loss of taste.
3. Superior salivatory nucleus - parasympathetic fibres to the lacrimal and salivary glands come through the superior salivatory nucleus. They branch at the geniculate ganglion into 2 nerves - the greater petrosal nerve and the chorda tympani nerve. Decreased lacrimation occurs if these are involves
4. Spinal nucleus of V - CN V has three divisions (opthalmic, maxillary and mandibular) that provide sensation to the face. Involvement of the sensory ganglion can lead to sensory disturbances in addition to the motor deficits that come with involvement of CN VII.

⚠️ Risk factors

• Previous VZV infection or vaccination
• ≥50 years of age
• Immunosuppression

😷 Presentation

• Ipsilateral facial palsy - usually with a sudden onset.
• Vesicular rash - around the ear ipsilaterally.
• Ear pain - can be quite severe.
• Loss of taste
• Epiphora - excessive lacrimation.
• Hyperacusis - over sensitivity to sounds.
• Sensorineural hearing loss
• Tinnitus
• Vertigo

🫠

Ramsay Hunt syndrome vs Bell’s palsy

Both Ramsay Hunt syndrome and Bell’s palsy present with facial nerve dysfunction and both are caused by herpes viruses (VZV and HSV). However, the presence of a rash and severe pain helps differentiate between Ramsay Hunt and Bell’s palsy.

🔍 Investigations

⭐️ Diagnosis of RHS is a clinical diagnosis.

• 🏆 VZV PCR - if there is uncertainty regarding the aetiology, vesicular lesions, if present, can be swabbed directly for confirmation by PCR. VZV PCR has nearly 100% sensitivity and specificity.

🧰 Management

🚨 Complications

• Corneal abrasion
• Secondary bacterial infection
• Postherpetic neuralgia
• Chronic tinnitus
• Vestibular dysfunction