Local Administration of Methylcobalamin and Lidocaine for Acute Ophthalmic Herpetic Neuralgia

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Local Administration of Methylcobalamin and Lidocaine for Acute Ophthalmic Herpetic Neuralgia
Key Take-Away: 
  • Previous studies recommend lidocaine as a first-line therapy for post herpetic neuralgia, (PHN), which could be efficacious in relieving pain associated with Acute ophthalmic herpetic neuralgia (AOHN).
  • Local treatment allows direct delivery of MeB12 to topical HN-damaged subcutaneous and neuronal tissue to obtain more rapid and effective responses in nerve fibers affected by AOHN than achieved by systemic administration.

Herpes zoster ophthalmicus (HZO) is caused due to the reactivation of varicella zoster virus (VZV), causing pathognomonic vesicular eruption in the ophthalmic division of trigeminal nerve. It involves severe neuritic pain and neuralgia and ophthalmic branch is one of the common sites of postherpetic neuralgia (PHN) in elders. It can severely impact quality of life (QoL).

ABSTRACT: 
Background: 

Herpes zoster ophthalmicus (HZO) is caused due to the reactivation of varicella zoster virus (VZV), causing pathognomonic vesicular eruption in the ophthalmic division of trigeminal nerve. It involves severe neuritic pain and neuralgia and ophthalmic branch is one of the common sites of postherpetic neuralgia (PHN) in elders. It can severely impact quality of life (QoL). PHN is a pain that persists for 90 days of acute zoster infection.

Acute ophthalmic herpetic neuralgia (AOHN), a severe and difficult to manage complication is likely to be due to an immediate nociceptive response. Local inflammation and tissue damage stimulates the afferent and subcutaneous fibers of V1, which manifest neurologically as pain. Cobalamin (Cbl, vitamin B12) has a specific affinity for neural tissues. MeB12 therapy may have beneficial pharmacologic effects on neurologic function in a variety of disorders like diabetic neuropathy, glossopharyngeal neuralgia, autistic disorder and Alzheimer’s disease-related cognitive decline.

Rationale for research

  1. Compared with other analogues of vitamin B12, MeB12 is most effective in terms of uptake by the subcellular organelles of neurons.
  2. Therefore, MeB12 along with lidocaine may be a better treatment for neuronal disorders through effective systemic or local delivery in AOHN.
  • Objective

To evaluate the therapeutic efficacy of combined methylcobalamin and lidocaine for AOHN

Methods: 

 

Study outcomes

  • Primary outcome:  Reduction in pain at 12 months
  • Treatment efficacy was assessed based on rash healing time, alteration of pain intensity and interference with quality of life.
  • Time-points
    • Efficacy: Baseline and 1, 3, 6, 12 months
Results: 

  • Baseline: The time (hours) to start and full opening of the affected eye and time (hours) to start and full crusting significantly reduced in both treatment groups (P < 0.05 vs. controls)
  • The mean pain scores in A1 (2.6_0.7) and B1 (1.2_0.8) decreased significantly compared to A0 (7.0_1.7) and B0 (5.6_1.9) and the difference between the two therapeutic strategies significantly increased over time
  • The median minimum intervention time was 6 days in B1 and 11 days in A1. The incidence of postherpetic neuralgia (PHN) was 2.04% at 3 months
  • The median minimum intervention time was 6 days in B1 and 11 days in A1. The incidence of postherpetic neuralgia (PHN) was 2.04% at 3 months
Conclusion: 

The result suggests that MeB12 has a significant analgesic effect on AOHN.MeB12 combined with lidocaine not only improved detumescence and cutaneous healing of the affected area, but also exerted a significant and sustained analgesic effect on AOHN. Furthermore, the incidence of PHN was also significantly reduced. Local methylcobalamin intervention within 4-7 days of onset may be an effective therapeutic option for AOHN.

Cbl may exert antinociceptive and anti-inflammatory effects against acute and chronic pain. In this study, analysis of the longitudinal data in mixed models indicated significant differences in the changes in mean pain score between two different treatment methods. In A0 and B0 groups treated with intramuscular MeB12, in addition to local lidocaine injection, a significant response was observed up to 14 days relative to baseline. The rate of pain score change in control group decreased to 0.49 and 0.47 time-point after baseline for A0 and B0, respectively (P < 0.0001). However, only one of 24 subjects (4.2% for A0) or four of 25 subjects (16.0% for B0) receiving antiviral therapy had pain scores ≤ 3 at the end of 14 day treatment. The times for swelling reduction and rash healing were significantly shortened in both A1 (286.4_45.3; 385.7_68.9) and B1 (162.0_32.9; 239.3_39.9) than in A0 (440.0_67.4; 540.0_98.5) and B0 (338.9_40.6; 419.0_40.2), which implied that MeB12 combined with lidocaine exerted anti-inflammatory and detumescence effects on the affected area.

Pain Pract. 2015 Jul 22
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