Symptom-based characteristics and treatment efficacy of neuropathic pain related to spinal disorders

Neuropathic pain development and maintenance and its association with motor recovery after cervical spinal cord injury

BACKGROUND

In our published randomized controlled trial, we revealed that patients with acute ASIA Grade C incomplete cervical spinal cord injury (SCI) who underwent early surgery (within 24 h post-injury) had accelerated motor recovery at six months than those with delayed surgery (>2 weeks post-injury); however, neuropathic pain (NeP) worsened regardless of surgery timing. Here, we conducted post-hoc analyses to intensively assess NeP development and maintenance.

METHODS

Of 44 patients (median 64.5 years; three female; early intervention, n = 26), NeP was categorized into at-level and below-level pain and evaluated at  two weeks and one year after injury using the Neuropathic Pain Symptom Inventory (NPSI). We compared the two groups based on background characteristics. A mixed-design analysis of variance with sex as a covariate was conducted to analyze motor recovery and Health-related quality of life (HRQOL) in groups with severe (NPSI ≥ 10) or mild (NPSI < 10) pain.

RESULTS

Upper and lower limb motor impairments were comparable between both groups regardless of pain severity. Severe at-level pain remained stable and worsened at one year than mild at-level pain; however, the upper- and lower-limb motor scores and HRQOL had comparable recovery. Background characteristics did not affect severity or time course of NeP. Patients with severe below-level pain demonstrated slower lower-limb motor recovery than those with mild below-level pain, whereas HRQOL improved regardless of pain severity.

CONCLUSIONS

Both at-level and below-level NeP developed and persisted relatively early in the course of traumatic SCI with incomplete motor paralysis; their severities worsened over time or remained severe since onset.

Symptom-based pharmacotherapy for neuropathic pain related to spinal disorders: results from a patient-based assessment

Existing guidelines advocate an updated therapeutic algorithm for chronic neuropathic pain (NeP), but pharmacotherapeutic management should be individualized to pain phenotypes to achieve higher efficacy. This study was aimed to evaluate the efficacy of medications, based on NeP phenotypes, and to propose symptom-based pharmacotherapy. This retrospective study was enrolled 265 outpatients with chronic NeP related to spinal disorders. The patients were classified into three groups: spinal cord-related pain, radicular pain, and cauda equina syndrome. Data were obtained from patient-based questionnaires using Neuropathic Pain Symptom Inventory (NPSI) and the Brief Scale for Psychiatric Problems in Orthopaedic Patients, and from clinical information. The proportions of patients with ≥ 30% and ≥ 50% reduction in NPSI score for each pain subtype (spontaneous pain, paroxysmal pain, evoked pain, and paresthesia/dysesthesia) and drugs were evaluated. The pain reduction rate was significantly lower in patients with spinal cord-related pain, especially for paresthesia/dysesthesia. For spinal cord-related pain, duloxetine and neurotropin had insufficient analgesic effects, whereas mirogabalin was the most effective. Pregabalin or mirogabalin for radicular pain and duloxetine for cauda equina syndrome are recommended in cases of insufficient analgesic effects with neurotropin. The findings could contribute to better strategies for symptom-based pharmacotherapeutic management.