Spinal trigeminal nucleus lesions in trigeminal zoster-associated neuralgia: A retrospective cohort study on diagnostic value and prognostic factors.

BackgroundTrigeminal zoster-associated neuralgia (TZAN) is a refractory intractable craniofacial neuropathic pain with a high risk of progressing to postherpetic neuralgia. Abnormal T2-weighted magnetic resonance imaging (MRI) hyperintensity in the spinal trigeminal nucleus (STN) has been reported in TZAN patients, but its diagnostic value, influencing factors and association with prognosis remain insufficiently explored. This study aimed to investigate the correlation between STN lesions and TZAN and identify factors affecting STN signal characteristics and TZAN therapeutic efficacy.MethodsThis retrospective cohort study included 105 TZAN patients, 105 non-TZAN normal controls (NC) and 287 classical trigeminal neuralgia (CTN) patients who underwent cranial MRI at Shandong Provincial Hospital Affiliated to Shandong First Medical University between September 2018 and March 2024. Propensity score matching (1:1, caliper = 0.1) was used to balance baseline differences between the TZAN and CTN groups. STN lesions were evaluated in a blinded manner by two radiologists, and clinical data (pain Numeric Rating Scale scores, pregabalin dosage) were collected via medical records and 6-month telephone follow-up. Multivariate logistic regression analyzed factors associated with STN hyperintensity and TZAN efficacy (pain relief ≥ 80% defined as "excellent response").ResultsSTN lesion detection rate was significantly higher in TZAN than in NC (62.9% vs. 1.0%, p < 0.001) and matched CTN (68.9% vs. 0%, p < 0.001), with 62.9% sensitivity, 99.0% specificity and 81.0% accuracy for TZAN diagnosis. Age (odds ratio (OR) = 1.06, 95% confidence interval (CI) = 1.006-1.116, p = 0.030) and subacute phase (vs. acute: OR = 32.01; vs. chronic: OR = 46.40, both p < 0.001) independently predicted STN hyperintensity. STN-normal patients had better short-term efficacy (discharge Numeric Rating Scale = 2 (1, 3) vs. 3 (2, 4), p = 0.042; excellent response rate: 38.5% vs. 19.7%, p = 0.036) but no long-term difference (3 and 6 months post-discharge, p > 0.05). Chronic phase predicted poor prognosis (vs. acute: OR = 6.55, p = 0.005; vs. subacute: OR = 5.39, p = 0.017).ConclusionsSTN lesions are highly specific for TZAN and may serve as an auxiliary diagnostic indicator. STN hyperintensity is most prominent in elderly TZAN patients in the subacute phase, potentially acting as a subacute-phase imaging marker. Early intervention in subacute TZAN may be critical for improving prognosis.