Herpes Zoster: this disease manifests itself with microscopic skin lesions and pain

Herpes zoster, commonly known as shingles, is a viral disease caused by the varicella-zoster virus (VZV)

It preferentially affects the nerve ganglia. It is a widespread disease and we are surrounded by it on a daily basis.

Our immune defences are such that they usually inhibit or minimise viral activity.

It is estimated that 1 in 10 people will have at least one episode of shingles in adulthood.

What are the causes? How is it treated?

Symptoms of Herpes Zoster

In some cases, the immune barrier breaks down and the virus begins to increase its local diffusion and dispersion capacities, preferentially damaging nerve fibres and, in its initial appearance, causing local reactive phenomena in the skin.

These are characterised by micro lesions and pustules (similar to those of chickenpox), in a very obvious and painful form that typically follows the course of the underlying nerve, affecting mainly:

• face;
• chest;
• lower limbs.

An episode usually lasts from 2 to 4 weeks and its main symptom is pain.

It may happen that, before the appearance of pustules, other disorders may occur such as:

• fever;
• headache
• itching;
• tiredness;
• paresthesias (altered perception of sensory stimuli).

In these cases, it is always better to consult your general practitioner to avoid the risk of the situation worsening and to start the most suitable treatment as soon as possible.

Herpes Zoster, the cure

When this rash appears, the typical antiviral, anti-inflammatory and pain-relieving treatment is used, although it is always advisable to check that there are no concomitant pathologies that have in some way favoured the opening of the immune barrier, such as, for example, neoplastic (tumour) forms.

Postherpetic neuralgia (PHN)

If the pain persists after the rash has resolved, a clinical picture called post-herpetic neuralgia (PHN) has most likely developed.

Sometimes the pain is present before the herpetic rash, sometimes it occurs during the acute phase, sometimes immediately after healing or even several weeks or months after the clinical picture of the skin has healed.

Risk factors for the development of PHN are:

• female sex;
• advanced age;
• pain or disturbance of sensation prior to the development of the rash;
• greater severity of pain during the acute cutaneous phase of herpes zoster;
• wider distribution for shingles rash.

Data from two major clinical trials showed that 20% of patients over 60 years of age, correctly treated with antiviral in the acute phase, developed PHN.

This number increases to 41% when considering those patients with intense pain during the rash and 47% when considering only female patients with intense pain during the zoster rash and patients with pre-existing pain or sensitivity disorder in the area of the rash.

The causes of PHN

The problem arises because the virus has damaged the nerve fibres that carry sensitivity in the areas where the herpes infection has developed.

It is imperative for the pain therapist to intervene before irreversible nerve damage occurs.

Microscopically, a form of degeneration of the nerve’s protective membrane (myelin), which covers the nerve at the ganglion level but also along its entire course, is visible on the surface of the nerve.

The pain of postherpetic neuritis is irreducible and greatly limits the patient’s quality of life because it never stops, day or night.

It limits sleep, eating, especially if it is at the level of the facial tract, breathing if it is at thoracic level, so it is an extremely serious and important disease to treat.

Treatment for post-herpetic neuralgia

In this regard, there are specific and targeted treatments, transcutaneously, along the course of the nerve, which can be carried out either with the aid of a needle, with the injection of suitable anaesthetic or adjuvant drugs, or with the simpler application of very effective patches.

Herpes Zoster patches and drugs administered in cases of shingles

The first of the drugs to be administered in this way is lidocaine, a highly concentrated local anaesthetic that is continuously released through a patch for 12 hours, maintaining a constant level of analgesia where it is applied, after which it must be replaced, especially at the beginning, when the neuritis begins.

When the neuritis is already established, a very powerful drug is used, capsaicin, derived from chilli extract.

This, always applied by means of a patch with a very high concentration, must be carried out in a protected hospital environment and with great caution because the dispersion of capsaicin can be very damaging to the eye and skin of the operator performing it.

The application lasts about 1 hour, after which, if efficacy is achieved, the patient has an improvement, although sometimes not definitive, for up to 6 months.

Electrical neuromodulation

There are also therapies that make it possible to modulate the electrical signal of the nerve damaged by the virus: these treatments fall into the category of electrical neuromodulation.

These are very sophisticated systems which, by inserting a very thin electrode into the patient’s spinal column, allow the fibres carrying the pain to be stimulated selectively.

The implantation takes place in 2 phases and is performed under local anaesthesia:

• In the first phase (cfase test) the thin lead is placed. The system is left in place temporarily for a few weeks so that the patient can assess how effective it really is;
• In the second phase, if the patient is satisfied with the analgesia obtained, the pulse generator, which is very similar to a cardiac pacemaker, is implanted.

Postherpetic neuropathy can present in forms that are apparently clinically similar, but very different in terms of the mechanism that generates it.

This is why it remains one of the most difficult chronic pain conditions to treat.

Many times, in fact, two patients with apparently similar post-herpetic pain have completely different underlying mechanisms that require equally different treatments.

There are therefore some forms in which, unfortunately, satisfactory pain relief cannot be achieved.

In addition to this, the patient must be considered as a whole: comorbidities (presence of other diseases) and the condition in general must be considered.

Also the affective side has to be considered because it is a chronic pain, a pain that limits a lot the quality of life and induces anxiety and depression.

This is why it is important that he also embarks on a psychological journey.

The patient who sees a possible solution to his problem is a patient who will tend to recover.

Once the symptoms and manifestations have disappeared, the disease remains under the control of the organism itself, which regains the domain of immunocompetence.

The risk of relapse is always present because the virus, once nested in the ganglia, never disappears definitively, a bit like cold sores.

The patient’s state of well-being is the best prevention. If he or she is well, healthy, has no problems and has no major chronic concomitant diseases, this disease can be safely kept under control.

Herpes zoster vaccine

There is also a recent piece of good news: from 2021, the new vaccine to prevent herpes zoster already approved by the US Food and Drug Administration (FDA) in 2017 and by the European Medicines Agency (EMA) in 2018 will be available, also in Italy.

It is a recombinant adjuvanted vaccine (i.e. it does not contain a live component of the varicella-zoster virus) that allows the body to produce specific antibodies against the varicella-zoster virus, thus counteracting the development of shingles and its complications.

It is administered in 2 intramuscular doses two months apart.

Several studies have evaluated the vaccine’s effectiveness in preventing shingles and post-herpetic neuropathy.

In particular:

• in people over 50, the vaccine was 97% effective against shingles and 100% effective against post-herpetic neuropathy;
• in the over-70s, the efficacy was 91% against shingles and 89% against post-herpetic neuralgia.

Read Also:

What Is Impetigo In Adults And Children And How To Treat It

Shingles, The Painful Return Of The Chickenpox Virus

Source:

GSD