Basel Al Rawashdeh MD*, Adel Batarseh Msc**, Sael Abuseif MD*,
* dermatologist & dermatosurgeon from the internal medicine department, dermatology section Queen Alia Hospital (QAH), Amman-Jordan
** Clinical Pharmacist (QAH)
* from the internal medicine department, dermatology section (Princes Ali Hospital)

Correspondence:
Dr Basel Alrawashdeh (QAH)
P.O.Box 340771, Postcode: 11134
Amman- Jordan
Mobile 00962799540530
Email basiltaher@hotmail.com

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INTRODUCTION

Post Herpetic Neuralgia (PHN) is defined as pain that persists more than three months after an individual has experienced shingles, a viral infection also known as Herpes Zoster. The condition affects the nerves and skin, and the pain can burn, ache, or resemble an electric-shock feeling.^1,2

About 15% of people who have had chickenpox (almost everyone) develop zoster sometime during their life, and about 10% of people with zoster develop neuralgia. In older adults, as many as 50% develop neuralgia after zoster, one or more months after the rash.
Many modalities are used to treat PHN. These include topical therapy as Lidocaine patches 5% or capsaicin and oral therapy as Tricycle antidepressants or Anticonvulsants with variable improvement.
We designed our study to determine the impact of topical lidocaine gel 2% on pain qualities associated with PHN.

METHODS

This descriptive study was conducted at Princes Hashem and Queen Alia Hospitals from 1st of July 2007 to 31 of August 2008.

A total number of 47 patients were included in the study, and male to female ratio was (5:1). Age was between 28-65 years with a median of 48 years.

All fitted the criteria of PHN (pain that persists more than three months after an individual has experienced zoster and disappearance of rash or any pain occurring after healing of herpes zoster) with moderate to severe pain. Analyses for the type of pain were done and patients categorized to have lancinating pain, burning pain or other types of pain. Two of the patients were on Aspirin therapy for ischemic heart disease and three were on non steroidal anti-inflammatory drugs for osteoarthritis

All applied Lidocaine gel 2% to the affected area after three months from the onset of herpes zoster infection four times daily for two weeks and follow up was done during this period and two weeks after starting the therapy. To assess improvement of the pain direct questions were asked of the patient.
What type of pain do you have?
Did you feel a good improvement of your pain?

RESULTS

Of the 47 patients who were involved in our study, 28 (60%) of the patients complained of lancinating pain, where 22 (79%) showed positive improvement, and 12 (25%) complained of burning pain where only 5 (41%) showed positive improvement, while 7 (15%) complained of other types of pain and 6 (86%) showed positive improvement. While from those patients only 0.06% (3 of 47 patients) showed skin irritation and 0.04% (2 of 47 patients) were non-compliant.
So 70 % (33) of the patients felt a positive improvement within two weeks; while 30% (14) of the patients showed no improvement in general; and this is shown (Table 1).
The calculated value of chi-square is 6.26 and the calculated p-value is <0.05 which is statistically significant in our study.

Table 1 results of data analysis

Table 2. Treatment Options for Post herpetic Neuralgia

DISCUSSION

Post herpetic neuralgia (PHN) is the commonest and most intractable sequel of zoster and defined as persistence or recurrence of pain after 3 months from the onset of zoster.
Its severity increases with age.³
The pain has two main forms: a continuous burning pain with hyperesthesia and a spasmodic shooting type.⁴
PHN is generally a self-limited disease. Symptoms tend to abate over time. Less than 25% of patients still experience pain at six months after the herpes zoster eruption, and fewer than 0.05% has pain at one year.⁵
A lot of modalities were used to treat PHN, which includes topical agents like capsaicin cream and oral, like tricyclic anti-depressants (Table 2)⁵
No single best treatment for PHN is known. Tricyclic antidepressants, topical capsaicin, gabapentin, and oxycodone are effective for alleviating PHN.⁶
Lidocaine is a local anesthetic agent used to relieve pain associated with shingles and post herpetic neuralgia with good tolerability.⁷ However with neuropathic pain some studies suggest to use local anesthesia for both acute and chronic pain which works by suppressing activity of spontaneously active fibers in neuromas,⁸ depresses c afferent fibre evoked activity in the spinal cord⁹ and silence dorsal root ganglion discharge without blocking nerve conduction.¹⁰

Lidocaine preparations are also sometimes used. Lidocaine gel 2% has been studied and shown to have good results with no side effects.¹¹

Lidocaine patch an effective local anesthetic can reduce both pain and allodynia in a large proportion of PHN¹² Patients can apply up to four large patches around the affected nerve not more than 12 hours but side effects like redness or swelling to application site sometimes occur. So because of its minimal risk of systemic adverse effects or drug-drug interactions and proven efficacy, the lidocaine patch 5% has been recommended as a first-line therapy for the treatment of the neuropathic pain of PHN.¹³

In our study we used lidocaine gel 2% as a symptomatic treatment of PHN and our results showed that it is a good treatment for post herpetic neuralgia especially lancinating (shooting) pain with 70% improvement within two weeks, and with less side effects (skin irritation 0.06%) and cost than Lidocaine patch 5% and can be easily spread all over the affected area.

CONCLUSION

Lidocaine gel 2% is a good symptomatic treatment for PHN and we recommend it especially for lanicating pain type; where skin test is needed to exclude skin allergy.

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