Quantitative Sensory Changes Following Posterior Spinal Fusion to Treat Adolescent Idiopathic Scoliosis.

BACKGROUND

Sensory changes surrounding the incision frequently develop after posterior spinal fusion (PSF) to treat adolescent idiopathic scoliosis (AIS). Anecdotally, patients may experience sensory changes on the chest wall. Such postsurgical sensory changes are not well described quantitatively. This study aims to evaluate the presence, intensity, and duration of mechanical sensory changes in AIS patients postoperatively.

METHODS

A prospective cohort of AIS patients, 10 to 21 years old, was followed. Quantitative sensory testing (QST) included touch detection threshold [mechanical detection threshold (MDT)] and pain detection threshold (MPT), using VonFrey monofilaments and pinprick stimulators. QST was performed at 3 sites at T6: the right and left chest at the nipple line and adjacent to the incision below the inferior angle of the scapula. QST at the thenar eminence was the control. QST was collected at baseline, 3 days, 1, and 6 months postoperative.

RESULTS

Thirty-four patients (21% males; mean age: 14.9 years old; median preoperative curve: 58 degrees) completed all testing. Mean deformity correction was 64% (SD: 10.4). Adjacent to the incision site, MDT was significantly higher compared with baseline at 3 days and 1 month ( P < 0.001) but not at 6 months ( P = 0.19), whereas MPT was significantly higher at 3 days, ( P < 0.001), 1 month ( P < 0.001), and 6 months ( P = 0.001). For the chest wall in all patients, MPT was higher on the left chest at 3 days ( P = 0.04) and on the right chest at 3 days ( P = 0.022) and 1 month ( P = 0.05). For patients with right-sided curves, MDT ( P = 0.01) and MPT ( P = 0.015) overall were significantly higher on the concave side (left) chest postoperatively.

CONCLUSIONS

PSF is associated with sensory disturbances that are detectable within days, persist at 1 month, and improve at 6 months postoperatively adjacent to the incision and on the chest wall. We suspect that these sensory changes are transient. Describing postoperative sensory changes will help us better set postoperative expectations for patients undergoing PSF.

LEVEL OF EVIDENCE: Level I.