Regional Anesthesia to Relief Zoster Pain

Study Model:

Randomized prospective registered After approval by the ethical committee of VinMec international Hospitals Institution , after approved registration prior to start the study to www.clinicaltrial.gov, 80 patients will be enrolled to participate to the study.

Inclusion criteria; Acute zona diagnosed by the dermatologist Acute skin rash with blisters in a limited area on one side of the body Eruption Unilateral On dermatome between C5 and S2 Age 18 to 85 years Old [YO], males and females American Society of Anesthesiologists score [ASA] grades I \& II Patient who accepted to participate as volunteers and signed an informed consent

Exclusion criteria; Psychiatric disease Central nervous system disease or pre-existing neuropathy Coagulation abnormalities or anti-coagulant treatment (heparins Anti vit K anti thrombin) Contra indication to perform a peripheral nerve block or interfascial block Infection of the skin overlying the puncture site of the block Allergy to local anaesthetic or prednisolone Contra indication to prednisolone ASA III and IV Morbidity Obese BMI > 30 Pregnant woman Baseline evaluation; Date of first rash appeared Pain VAS score from 0 no Pain to 10 the worst imaginable pain Localization of the pain (Skin mapping of the painful area and allodynia area) Quality of life before the rash evaluated by the quality of Life questionnaire SF36 published with a certified translation in Vietnamese As soon as the diagnosis will be done by dermatologist the following treatment will be prescribed according to international published standards of Herpes; Oral administration of Acyclovir 800 mg 5 times a day for 7 days Oral administration of prednisolone except if contra indication 30mg twice daily on d1 > 7 15mg twice daily on d8 > 14 7.5mg twice daily on d15 > 21

Patient flow chart:

Randomization Done by an administrative assistant using a computer program with block randomization.

Group Control = medical treatment with the following pain killers Pain medications Oral administration of Gabapentin 300 mg/d on day 1 and 2 600 mg on day 3 and 4 if pain persists 900 mg on day 5 and 6 if pain persists Oral administration of Paracetamol up to 3 g per day Use of oral narcotic contra-indicated A pain assessment will be done at day 7 if Pain scores < 4 medical treatment will be continued. If Pain score > 4 Patient will be shifted to the group Intervention and will follow the same protocols of this group with randomization done by an administrative assistant using a third computer program table of randomization.

Group Intervention = Early block a second randomization will be done immediately after the first one by an administrative assistant using a second computer program table of randomization.

Single Shot [SS] block : the patient will receive a regional anaesthesia by Inter fascial block, peripheral nerve block. The type of block would be the most appropriate to cover the dermatomes involved in the Herpes according to the mapping done with the higher ration benefit risks. Choice of Block by an anesthesiologist expert in regional anaesthesia techniques. After the block performance if the pain comes back patient will receive the standard medical treatment as in the group medical treatment Repeated [R] Blocks : the patient will receive a regional anaesthesia by Inter fascial block, peripheral nerve block. The type of block would be the most appropriate to cover the dermatomes involved in the Herpes according to the mapping done with the higher ratio benefit risks. The choice of the block will be done by an anesthesiologist expert in regional anaesthesia techniques. The block will be repeated every 48h until the pain will reach VAS < 3 6 h after block recovery.

all the blocks will be performed under US guidance combined if peripheral nerve block or peri plexic block with Neurostimulation guidance to increase the safety of the block performance at the higher level.

The choice of Local anesthetics used will be Ropivacaine 0.5% with the same posology used to performed a regional anaesthesia for surgery.

The patient will be discharged 2 hours after the block performance Follow up

The follow up will be done by :

an pain nurse to analyse VAS at Week 1, 2 and 3 after the inclusion of the patient Satisfaction of patient 0-10 a pain physician to analyse at Month 1, 2 3 and 6 after 1st eruptive sign of Herpes Zona [HZ] eruption development of post herpetic neuralgia defined as Persisting pain beyond the crusting of lesion Pain lasting more than 1, 2 ,3 or 6 months after the acute infection Neuropathic pain with a Douleur Neuropathic 4 [DN4] scale score > 4 DetectPain scale score > 19 Pain level VAS Mapping area of pain to calculate surface Quality of life score at Month 2 3 6 after start of eruptive phase Primary Outcome Quality of pain relief in acute phase VAS score at 1 day / 3 day/ 7 day / 14 Day / 21 day Mapping area surface at day 1, 7 , 14 and 21

Secondary Outcome Development of Neuropathic pain Scale DN4 score > 4 Scale Pain detect Score > 17 Pain intensity Quality of life (QoL) Using the 36 item Short form Health survey [SF36] variation compared to initial assessment

Sample size calculation An estimated 14 patients per group were required to detect a 25% reduction in the mean VAS score in block groups compared to standard treatment group, with a power of 80%, a 2-tailed α of 5%, and a mean VAS-score of 7.25 (SD 1.51) [14] of standard treatment group in the pre-test.

The sample size of 80 patients allowed for a 10% loss to follow-up. Statistical analysis plan Statistical analysis will be performed using STATA 14.0 software. Statistical significant will be set at 5% level (2-tailed). A QoL score will be derived from related variables as stated above, using factor analysis.

Data will be summarized using n (%) for categorical data and median (inter-quartile ranges) for continuous data. Analyses will include Chi-square or Fisher's exact test where appropriate for binomial data. Continuous data will be compared by non-parametric tests.