Effectiveness of Duloxetine for Postsurgical Chronic Neuropathic Disorders after Spine and Spinal Cord Surgery

Abstract

Study design: This is a retrospective observational study with an outpatient setting.

Purpose: This study aimed to describe the effects of duloxetine (DLX) administration for postsurgical chronic neuropathic disorders (both pain and numbness) following spinal surgery in patients without depression.

Overview of literature: Although several reports indicated the potential of DLX to effectively treat postoperative symptoms as a perioperative intervention, there have been no reports of its positive effect on postsurgical chronic neuropathic disorders.

Methods: A total of 24 patients with postsurgical chronic pain and/or numbness Numeric Rating Scale (NRS) scores of ≥4 were enrolled. All patients underwent spine or spinal cord surgery at Keio University Hospital and received daily administration of DLX for more than 3 months. The mean postoperative period before the first administration of DLX was 35.5±57.0 months. DLX was administered for more than 3 months at a dose of 20, 40, or 60 mg/day, and the degree of pain and numbness was evaluated using the NRS before administration and 3 months after administration. Effectiveness was defined as more than a 2-point decrease in the NRS score following administration.

Results: In terms of the type of symptoms, 15 patients experienced only numbness, eight experienced both pain and numbness, and one experienced only pain. Of the 24 patients, 19 achieved effective relief with DLX. DLX was effective for all patients with postsurgical chronic pain (n=9), and it reduced postsurgical chronic numbness in 18 of 23 patients. No significant difference was observed in background spinal disorders. DLX was not effective for five patients who complained only of postsurgical chronic numbness.

Conclusions: This study reports the effectiveness of DLX for postsurgical chronic neuropathic disorders. Although DLX reduced postsurgical chronic pain (efficacy rate=100%) and numbness (78.3%) in certain patients, further investigation is needed to determine its optimal use.

Keywords: Chronic pain; Duloxetine hydrochloride; Numbness; Postsurgical neuropathic disorders.

Fig. 1

Post-surgical chronic pain and numbness assessed by the Numeric Rating Scale (NRS). (A) The mean NRS pain score (n=9). Duloxetine (DLX) reduced post-surgical chronic pain by more than 2 points on the NRS. All nine patients with post-surgical chronic pain were in the E group. There was a significant decrease in the NRS pain scores after 3 months of DLX treatment compared with baseline (before DLX administration). (B) The mean NRS post-surgical chronic numbness scores (total n=23). The E group patients with numbness (n=18) exhibited a significant decrease in symptoms 3 months after DLX treatment initiation, while the N group patients with numbness (n=5) showed no symptom relief. NS, no significant difference. ^**p<0.01.

Fig. 2

The intensity of each post-surgical chronic symptom. Pain and numbness were evaluated with the Numeric Rating Scale (NRS) as follows: NRS score ≥7 as severe, NRS score of 4–6 as moderate, NRS score of 1–3 as mild, and NRS score of 0 as none. (A) The change in pain intensity before and 3 months after duloxetine (DLX) treatment. Two patients had complete pain relief (NRS=0) after 3 months of DLX treatment. (B) The change in the intensity of numbness before and 3 months after DLX treatment.

Fig. 3

(A, B) Assessment of improvement in each symptom. The degree of symptom relief was defined as follows: symptoms with a decrease in the Numeric Rating Scale (NRS) score ≥2 as much improved, a decrease in the NRS score more than 50% compared with baseline or NRS ≤2 after 3 months of treatment as very much improved, and a decrease in the NRS score ≤1 as no change. Among the patients with post-surgical chronic pain, 33% showed a very much improved change, and 66% showed a much improved change. For post-surgical chronic numbness, 39.1% patients each showed very much improved and much improved changes (nine patients each), while 21.7% exhibited no change in numbness.