Shingles

Shingles Pain

Chickenpox and shingles are caused by an infection of the Varicella-zoster virus (VZV). The medical term for chickenpox is varicella and for shingles, it is called herpes zoster. While chickenpox usually occurs during childhood, the VZV remains in the body. VZV can become reactivated later in life, causing episodes of shingles. Although shingles is most common amongst the elderly, it is possible for the virus to reactivate any time the immune system is compromised.

Shingles is often a very painful condition. Although the rash associated with shingles may only persist for a short time; the pain associated with nerve damage can persist for weeks, months and sometimes years. Persistent, chronic pain that remains for more than four months after the original infection is called postherpetic neuralgia or postherpetic neuralgia.

Why Do People Get Shingles?

VZV is present in the body after an episode of chickenpox. As we age, immunity decreases and it becomes harder for the body to fight off infections. When VZV is able to reactivate, this causes an episode of shingles. Immunity naturally decreases as we age. Decreased immunity may also be caused by cancer and chemotherapy, HIV, or any number conditions that lessens the body’s immune response.

Shingles causes a painful rash. Pain is due to both short term inflammation and damage done to the nerves by the virus. Once the rash is resolved, the pain can continue. The persistent pain associated with postherpetic neuralgia is due to the virus’s effects on different nerves within the brain and spinal cord. Shingles and postherpetic neuralgia can affect sleep, appetite and libido since the intensity of the pain often interferes with these activities.

There is currently a vaccine for shingles. The vaccine is a preventative treatment for both shingles, and therefore postherpetic neuralgia.

Shingles to Postherpetic Neuralgia

The amount and duration of pain associated with shingles can vary:

• 30 days of pain or less is considered an acute phase
• If pain lasts longer than 30 days but shorter than 4 months, it is considered a subacute phase
• If the pain persists beyond four mouths, it is then considered postherpetic neuralgia.

Types of Postherpetic Neuralgia Pain

The most common places on the body that have pain with postherpetic neuralgia include the face, neck and upper to mid back. Pain can be burning, sharp or stabbing. It’s possible that the pain can occur all the time or pain can come on suddenly and randomly.

Many people with postherpetic neuralgia also experience a sensation called allodynia. This means they have increased sensation in specific areas and things that are typically benign, such as light touch, become painful.

Additionally, postherpetic neuralgia may cause numbness to certain areas of the skin when they are touched. These areas may then experience bouts of spontaneous pain, even when they are not touched.

Shingles very often causes scaring of skin tissue. This can be due to the initial viral infection or due to scratching during the course of the rash.

Pain from postherpetic neuralgia has been found to last anywhere from several (at least 4) months, to years after the initial infection. A majority of patients will find relief within a year but some need lifelong pain management.

Diagnosis of Postherpetic Neuralgia

Postherpetic Neuralgia is usually a simple diagnosis. If a person had shingles and their pain persists for more than four months, they are diagnosed with postherpetic neuralgia. Should a patient come in with persistent pain and they don’t recall, or were never diagnosed with shingles, there is a test that can be performed. Cerebrospinal fluid (CSF) is collected and the amount of virus is measured in the central nervous system. The results can indicate if the patient has postherpetic neuralgia. This should only used when necessary as obtaining CSF can be uncomfortable for the patient.

The older a patient is when their shingles infection occurs, the more likely they are to develop postherpetic neuralgia. In addition, if the rash from the shingles infection was severe, the patient is more likely to develop postherpetic neuralgia.

Treatment Options for Postherpetic Neuralgia

Since postherpetic neuralgia is a chronic pain condition, and not in the acute viral phase, the medication and therapies involved in treatment are aimed at pain relief. Prescription medication should be considered on a case by case basis since each type can have side effects specific to the patient. Medication should be used at a lower dosage and then slowly increased. This will help to find the best pain relief therapy for the patient while keeping side effects to a minimum. Typical treatment approaches for postherpetic neuralgia are as follows:

• Anticonvulsants such as gabapentin, pregabalin, or valproic acid reduce the piercing or stabbing type of pain. This should be the first approach for most patients with postherpetic neuralgia. These should be used with caution if a patient has pre-existing kidney or liver issues.
• TCAs (Tricyclic antidepressants) like amitriptyline if the previous anticonvulsants are not appropriate. Patients with heart disease, epilepsy, or glaucoma should not use TCAs. In addition, TCAs should be used with caution if an elderly patient has any dementia-like issues since these can be made worse. Initially, there may be a need for additional pain management therapies as it can take up to three weeks before TCAs begin to reduce pain.
• Topical medications such as capsaicin. This therapy should be used if the patient has confined areas of mild pain and does not want to use long-term oral medications. However, capsaicin, in particular, has uncomfortable side effects (burning and stinging) and if needed in concentrated doses, must be applied by a healthcare professional. Typically it needs to be combined with lidocaine and a patient may need short-term, post-treatment opioids.
• Opioids are quite powerful and have the potential for abuse or possible (unintentional) overdose. As such, they should be used cautiously. Opioids can be combined with other medications to provide immediate relief but should be tapered off once an alternative pain management solution is determined
• Spinal glucocorticoid injections are shots that are administered into the back. The medication goes directly into the inflamed nerve arising from the spine.  This can be used if no other pain management options are providing relief. However, these injections will not work for some types of facial pain. There are mixed results on whether these injections work for long-term pain relief for postherpetic neuralgia. While the risk is low, there are serious reactions that can occur as a result of complications.
• Botulinum toxin injection has not been extensively researched for postherpetic neuralgia pain but initial results seem promising.
• Lidocaine, both topical and intravenous, may provide some short-term pain relief but has not been proven to work long-term for postherpetic neuralgia patients.
• NMDA receptor antagonists can provide pain relief but are needed at doses that cause very serious psychological side effects. Their long-term effects on pain management have yet to be proven.
• Cryotherapy freezes certain nerves. Results have been limited and appear to be relatively short-term.
• Surgery involves direct electrical stimulation to various parts of the brain and spine. A spinal cord stimulator implant has been suggested for patients with refractory chronic pain in this condition.
• Over the counter drugs are of very limited value to patients with pain from either shingles or postherpetic neuralgia.

Conclusion

Shingles is caused by the same virus as Chickenpox (VZV). This virus remains in the body and can reactivate when immunity is compromised. If the pain from a shingles episode lasts for longer than four months, it is diagnosed as postherpetic neuralgia and can continue for a substantial amount of time. There are several treatments available to mitigate the pain associated with postherpetic neuralgia including anticonvulsants, TCAs, topical treatments, opioids, and spinal injections. Treatments should be considered based on the specific patient’s pain location and severity, in addition to any additional health concerns. Vaccination can help prevent shingles and postherpetic neuralgia.

If your pain does not resolve after a brief period, contact us so that we may help diagnose the problem and treat the underlying cause.  Do not let pain persist or else it may become chronic.