ORAL SMALL FIBER NEUROPATHY IN LYME DISEASE: IS BOTULINUM TOXIN TYPE-A A THERAPEUTIC OPTION IN ITS MANAGEMENT?—A CASE REPORT

Abstract

<h3>Objective</h3> Small fiber neuropathy (SFN) has been associated with posttreatment Lyme disease syndrome (PTLDS), a chronic widespread pain condition with an enormous impact on quality of life. SFN has been associated with hyperalgesia and allodynia, as seen in fibromyalgia. In PTLDS, peripheral and central pain mechanisms involving SFN are likely present, with neuropeptide imbalance, leading to increased nociceptive signaling. Refractory SFN cases are challenging to manage, and Botulinum toxin type-A (BTX-A) could be a treatment option with long-lasting results and fewer side effects. BTX-A analgesic effects may be related to the disruption of vesicular transport into the synapse, inhibiting local/peripheral and central release of algogenic neurotransmitters, preventing neurogenic inflammation and peripheral sensitization. <h3>Case Summary</h3> A 41-year-old woman was assessed in January 2019 at the Oral Medicine clinic for constant severe palatal pain. In January 2018 she was diagnosed and treated for Lyme disease after thorough specialist investigation. Subsequently, she was diagnosed with fibromyalgia, trigeminal neuralgia, and SFN, among other conditions related to PTLDS. Therapeutic trials with amitriptyline and pregabalin were partially palliative, but the palatal pain persisted. She correlated the pain with "swelling and inflammation." Clinical examination revealed no mucosal lesion but a mild erythema and edema on the incisal papilla, along with hyperalgesia and allodynia on the rugae; blocking of the nasopalatine nerve relieved the pain. A traumatic etiology was ruled out using an occlusal splint, and neuropathic pain (SFN) was our tentative diagnosis. Topical compounded neuropathic pain ointment was partially palliative. A trial of 30 units local BTX-A injections resulted in improvement of her symptoms. The total dose injected was increased to 50 units in subsequent sessions, at 3-month intervals. After the second session, she had a significant improvement, reporting the "best 30 days in three years." In January 2021, she confirmed the progressive improvement of her condition. <h3>Conclusions</h3> These results indicate that BTX-A may be an alternative in managing oral neuropathic pain in Lyme disease. To our knowledge this is the first report of the use of BTX-A for this condition. Further research is needed to provide evidence to these assumptions and the conception of clinical guidelines.