Herpes viruses are extremely common. Most people associate them with cold sores, genital herpes or shingles, but these viruses can sometimes affect much more than the skin.
Both Herpes Simplex Virus (HSV) and Varicella-Zoster Virus (VZV) have the ability to remain dormant within the nervous system after the initial infection. In certain circumstances, they can reactivate and affect the brain, spinal cord, cranial nerves or peripheral nerves.
Although serious neurological complications are relatively uncommon, some can be medical emergencies. Recognising the warning signs and seeking medical attention early can therefore be very important.
What Is Herpes Simplex Virus?
There are two main types of Herpes Simplex Virus:
- HSV-1 is most commonly associated with oral herpes and cold sores.
- HSV-2 is more commonly associated with genital herpes.
However, either type can infect different areas of the body.
After the initial infection, the virus does not completely disappear. Instead, it can remain inactive inside nerve cells for many years.
From time to time, the virus may become active again. Reactivation may occur during periods of illness, stress, reduced immunity or other physiological changes, although sometimes there is no obvious trigger.
Most reactivations cause relatively mild symptoms. In rare cases, however, HSV can affect the central nervous system.
Neurological Complications of Herpes Simplex
Herpes Simplex Encephalitis
One of the most serious neurological complications of herpes infection is Herpes Simplex Encephalitis (HSE).
Encephalitis means inflammation of the brain. HSV-1 is one of the most important causes of sporadic viral encephalitis.
Symptoms may include:
- Fever
- Severe headache
- Confusion or unusual behaviour
- Disorientation
- Memory problems
- Difficulty speaking
- Excessive sleepiness
- Seizures
- Loss of consciousness
Herpes Simplex Encephalitis often affects areas of the brain involved in memory, language, behaviour and emotions, particularly the temporal lobes.
This condition requires urgent hospital assessment and antiviral treatment, usually with intravenous acyclovir.
Early treatment is extremely important because untreated herpes encephalitis can result in severe neurological disability and may be life-threatening.
Herpes Simplex Meningitis
Herpes Simplex Virus can also cause viral meningitis, particularly HSV-2.
Meningitis is inflammation of the membranes surrounding the brain and spinal cord.
Possible symptoms include:
- Severe headache
- Fever
- Neck stiffness
- Sensitivity to light
- Nausea or vomiting
- General weakness
- Muscle aches
Some patients may experience recurrent episodes of HSV-associated meningitis.
Anyone developing symptoms suggestive of meningitis should receive prompt medical assessment.
Radiculitis and Nerve Root Inflammation
Herpes Simplex Virus can occasionally cause inflammation of the nerve roots emerging from the spinal cord, known as radiculitis.
Depending on the nerves involved, symptoms can include pain, numbness, tingling, weakness or altered sensation.
In rare cases, involvement of the sacral nerve roots may affect bladder or bowel function.
What Is Herpes Zoster?
Herpes Zoster, commonly known as shingles, is caused by the Varicella-Zoster Virus — the same virus responsible for chickenpox.
After a person recovers from chickenpox, the virus remains dormant inside sensory nerve ganglia.
Years or even decades later, it can reactivate and travel along a sensory nerve toward the skin, producing the characteristic painful rash of shingles.
The risk of herpes zoster increases particularly with:
- Increasing age
- Reduced immune function
- Certain illnesses
- Immunosuppressive medications
A typical shingles episode causes burning, tingling, sensitivity or pain, followed by a blistering rash affecting one side of the body.
However, because the virus is closely associated with the nervous system, shingles can occasionally produce significant neurological complications.
Neurological Complications of Herpes Zoster
Postherpetic Neuralgia
Postherpetic neuralgia (PHN) is one of the most common neurological complications of shingles.
In most people, shingles pain gradually disappears as the rash heals. In some patients, however, the affected nerve remains painful long after the skin lesions have disappeared.
The pain may continue for months and occasionally much longer.
Patients may describe the pain as:
- Burning
- Stabbing
- Electric-shock-like
- Deep aching
- Tingling
- Extreme sensitivity to touch
Sometimes even light contact from clothing or bedsheets can become painful. This phenomenon is known as allodynia.
The risk of postherpetic neuralgia increases considerably with age.
Treatment may include medications specifically used for neuropathic or nerve pain, rather than ordinary painkillers alone.
Ramsay Hunt Syndrome
When Herpes Zoster affects the facial nerve near the ear, it can cause Ramsay Hunt Syndrome.
Symptoms may include:
- Facial weakness or paralysis on one side
- Pain around the ear
- Blisters inside or around the ear
- Hearing changes
- Tinnitus
- Vertigo or dizziness
- Difficulty closing one eye
- Changes in taste
Because facial nerve recovery may depend partly on how quickly treatment begins, early medical assessment is important.
Herpes Zoster Ophthalmicus
Shingles can affect the ophthalmic branch of the trigeminal nerve, producing Herpes Zoster Ophthalmicus.
The rash typically appears around the forehead, scalp, upper eyelid or nose on one side.
This condition is particularly important because the eye itself may become involved.
Patients with shingles around the eye or forehead should seek prompt medical and ophthalmological assessment, especially when experiencing eye pain, redness, visual changes or sensitivity to light.
Cranial Nerve Complications
Varicella-Zoster Virus can occasionally affect other cranial nerves.
Depending on the nerve involved, patients may experience:
- Facial weakness
- Double vision
- Hearing loss
- Vertigo
- Difficulty swallowing
- Voice changes
- Altered facial sensation
Neurological examination can help determine which cranial nerve has been affected.
Herpes Zoster Encephalitis and Meningitis
Although uncommon, Varicella-Zoster Virus can cause inflammation of the brain or the membranes surrounding the brain.
Symptoms may include:
- Severe headache
- Fever
- Confusion
- Behavioural changes
- Excessive drowsiness
- Seizures
- Neck stiffness
- Loss of consciousness
Importantly, neurological complications of VZV do not always occur together with an obvious shingles rash.
Varicella-Zoster Vasculopathy
One particularly important neurological complication is Varicella-Zoster vasculopathy.
In this condition, Varicella-Zoster Virus causes inflammation and damage to blood vessels supplying the brain.
This may interfere with blood flow and, in some cases, contribute to a transient ischaemic attack (TIA) or stroke.
Symptoms can include sudden:
- Weakness or numbness on one side of the body
- Facial drooping
- Difficulty speaking
- Loss of coordination
- Visual disturbance
- Severe or unusual headache
Sudden neurological symptoms suggestive of stroke require immediate emergency medical attention.
Myelitis
Rarely, herpes viruses — particularly Varicella-Zoster Virus — may cause inflammation of the spinal cord, known as myelitis.
Symptoms may include:
- Weakness of the legs or arms
- Numbness or abnormal sensations
- Difficulty walking
- Balance problems
- Changes in bladder function
- Changes in bowel function
These symptoms require urgent neurological assessment.
Can Herpes Affect the Nerves Without a Rash?
Yes.
Although shingles is usually recognised because of its characteristic painful rash, Varicella-Zoster Virus can sometimes reactivate without producing obvious skin lesions.
This is sometimes referred to as zoster sine herpete.
In these cases, patients may develop nerve pain or, more rarely, other neurological manifestations without the classic shingles rash.
Because there is no visible rash, diagnosis can be more challenging and may require additional investigations.
How Are Neurological Complications of Herpes Diagnosed?
The investigations required depend on the patient's symptoms and suspected complication.
A neurological assessment may include a detailed history and examination followed, when appropriate, by tests such as:
Magnetic Resonance Imaging (MRI)
MRI of the brain or spinal cord may help identify inflammation or other neurological abnormalities.
Lumbar puncture
Cerebrospinal fluid (CSF) analysis may be necessary when meningitis or encephalitis is suspected. PCR testing can help identify viral DNA.
Electroencephalogram (EEG)
An EEG may be useful when encephalitis or seizures are suspected.
Blood tests
Blood tests may help assess infection, inflammation, immune status and other possible causes of neurological symptoms.
Additional investigations may be required depending on the clinical presentation.
How Are Herpes-Related Neurological Complications Treated?
Treatment depends on the virus involved and the neurological complication.
Antiviral medications such as acyclovir, valacyclovir or famciclovir may be used in appropriate cases.
Serious central nervous system infections, particularly suspected Herpes Simplex Encephalitis, generally require urgent hospital treatment with intravenous antiviral medication.
For shingles, antiviral treatment is generally most effective when started early after symptoms appear.
Neuropathic pain following shingles may require additional treatment. Depending on the individual patient, treatment options for postherpetic neuralgia may include medications used specifically for nerve pain and selected topical treatments.
Treatment should always be individualised according to the patient's age, medical history, kidney function, other medications and severity of symptoms.
When Should You Seek Urgent Medical Attention
Herpes infections are usually manageable, but certain neurological symptoms should never be ignored.
Seek urgent medical attention if herpes, shingles or a recent herpes infection is accompanied by:
- Confusion or sudden behavioural changes
- Loss of consciousness
- A new seizure
- Severe headache with fever
- Neck stiffness
- Sudden weakness or numbness
- Difficulty speaking
- New facial paralysis
- Sudden visual disturbance
- Shingles affecting the eye or surrounding area
- Severe vertigo associated with facial weakness
- New difficulty walking
- Loss of bladder or bowel control
These symptoms may indicate involvement of the brain, spinal cord, cranial nerves or other parts of the nervous system and require prompt assessment.
Can Neurological Complications of Herpes Be Prevented?
Not every complication can be prevented, but early recognition and appropriate treatment can reduce the risk of serious consequences in some situations.
Vaccination against Herpes Zoster (shingles) is also an important preventive measure for eligible individuals and can reduce the risk of developing shingles and its complications.
Patients should discuss their individual eligibility for vaccination with their doctor.
Herpes and the Nervous System: Why Early Recognition Matters
Herpes Simplex and Herpes Zoster are very common viral infections and, for most people, they resolve without serious complications. However, because these viruses remain dormant within the nervous system, they can occasionally reactivate and affect the nerves, brain or spinal cord.
Neurological complications can range from persistent nerve pain and facial weakness to meningitis, encephalitis, myelitis and, more rarely, complications involving the blood vessels of the brain. While these conditions are uncommon, recognising their symptoms early is important.
Symptoms such as new facial weakness, severe or persistent nerve pain, confusion, seizures, severe headache with fever, sudden weakness or numbness, visual disturbances, balance problems or difficulty walking should not be ignored and may require prompt neurological assessment.
The presence of herpes or shingles does not necessarily mean that the nervous system will be affected. Nevertheless, when unusual neurological symptoms develop during or after an infection, timely medical evaluation can help identify the cause, initiate appropriate treatment and reduce the risk of long-term complications.
Early recognition, accurate diagnosis and appropriate antiviral and neurological treatment remain the most important steps in protecting the nervous system from the potentially serious complications of Herpes Simplex and Herpes Zoster.