Primary cervical decompression surgery may improve lumbar symptoms in patients with tandem spinal stenosis.

Tandem spinal stenosis (TSS) refers to coexisting lumbar and cervical canal stenosis. Evidence regarding whether cervical decompression improves lumbar symptoms in TSS is insufficient. Therefore, we determined the effectiveness of cervical decompression surgery for patients with lumbar spinal stenosis (LSS) and cervical spinal stenosis. The records of 64 patients with TSS experiencing lumbar symptoms who underwent cervical decompression surgery between April 2013 and July 2017 at a single institution were retrospectively reviewed. We categorized patients into the Non-improved (n = 20), Relapsed (n = 30), and Maintained-improvement (n = 14) groups according to the presence or absence of improvement and relapse in lower limb symptoms in TSS following cervical decompression surgeries. Of 64 patients, 44 (69%) showed improved lower limb or low back symptoms, with 14 (22%) patients maintaining improvement. The preoperative cervical myelopathy-Japanese Orthopedic Association score and the preoperative number of steps determined using the 10-s step test were significantly lower in the Non-improved group than in the Maintained-improvement group. Receiver operating characteristic curve of preoperative 10-s step test results revealed 12 steps as a predictor for maintained improvement. The improvement of LSS symptoms following cervical decompression surgeries may be associated with the severity of cervical myelopathy as determined in clinical findings rather than in imaging findings. Patients with TSS having a 10-s step test result of < 12 steps were more likely to experience a relapse of lower limb symptoms following cervical decompression surgeries.