525: Cannabinoid Therapy for Refractory Trigeminal Neuropathic Pain: A Pilot Case Study

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic neuropathic pain, Pharmacological treatments, Assessment and Measurement of Pain/Nociception, Imaging (e.g. fMRI, PET, MRS)

Background and Aims: Trigeminal neuropathic pain (TNP) is a rare, chronic, and highly disabling condition, with an estimated prevalence below 0.5% in the general population, and frequently refractory to standard pharmacological management, leading to substantial functional and quality-of-life impairment. Although cannabinoids have emerged as a complementary therapeutic option for neuropathic pain, evidence in orofacial pain remains limited and largely based on subjective outcomes. This pilot study aims to describe the clinical and functional effects of adjunctive cannabinoid therapy in refractory TNP, integrating validated pain and quality-of-life instruments with three-dimensional facial stereophotogrammetry to objectively document changes in sensitized facial areas.

Methods: This pilot case study included two female patients with refractory trigeminal neuropathic pain (TNP), one post-traumatic and one idiopathic, unresponsive to conventional pharmacological and local therapies. Both received a balanced sublingual THC:CBD formulation (20 mg/mL each) following a structured titration protocol and were followed for eight weeks. Outcomes were evaluated using the Douleur Neuropathique 4 (DN4), Visual Analog Scale (VAS), WHOQOL-Bref, and Qualitative Sensory Testing (QualST). Three-dimensional facial stereophotogrammetry (Vectra H1, Canfield Scientific®) was used to objectively quantify hyperfunction and allodynia areas over time.

Results: Adjunctive cannabinoid therapy led to marked clinical improvement in both patients. Pain intensity decreased substantially, with VAS scores reduced from 9 to 4 and from 10 to 2, alongside a qualitative shift from shock-like paroxysmal pain to a more tolerable burning pattern. Functional gains were observed in chewing, mandibular movements, and oral hygiene. Three-dimensional stereophotogrammetry objectively demonstrated a pronounced reduction in sensitized facial areas, with extraoral hyperfunction decreasing from 113.72 cm² to 27.54 cm² and complete resolution of allodynia by week 8. WHOQOL-Bref scores improved across all domains, particularly the physical and psychological domains. No severe adverse events occurred.

Conclusions: This pilot case series suggests that cannabinoid therapy may represent a valuable complementary approach for managing refractory trigeminal neuropathic pain. Beyond clinically meaningful pain reduction and functional improvement, the combined use of psychometric instruments and three-dimensional facial stereophotogrammetry enabled objective and multidimensional documentation of therapeutic effects. This integrated assessment strategy strengthens the interpretation of clinical outcomes and supports the translational relevance of cannabinoids in orofacial pain management. Although limited by sample size, these findings provide preliminary evidence to justify future controlled studies incorporating objective imaging tools to better characterize treatment response in refractory trigeminal neuropathic pain.

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Presenting Author: Jardel Francisco Mazzi-Chaves
Submitting Author: Jardel Francisco Mazzi-Chaves

Senior Author: Laís Valencise Magri

IASP 2026 Global Year theme of Neuropathic Pain: Yes

• Jardel Francisco Mazzi-Chaves: PhD - University of São Paulo
• Alex Moreira Mélo: PhD - University of São Paulo
• Luiz Guilherme Spadon-Brito: MSc - University of São Paulo
• Júlia Carrer Hallak: MSc - University of São Paulo
• Glauce Crivelaro do Nascimento Marangoni: PhD - University of São Paulo
• Melissa de Oliveira Melchior: PhD - University of São Paulo
• Simone Cecílio Hallak Regalo: PhD - University of São Paulo
• Laís Valencise Magri: PhD - University of São Paulo