Current understanding of tandem spinal stenosis: epidemiology, diagnosis, and surgical strategy

Abstract

Tandem spinal stenosis (TSS) is defined as the concomitant occurrence of stenosis in at least two or more distinct regions (cervical, thoracic, or lumbar) of the spine and may present with a constellation of signs and symptoms. It has four subtypes, including cervico-lumbar, cervico-thoracic, thoraco-lumbar, and cervico-thoraco-lumbar TSS. The prevalence of TSS varies depending on the different subtypes and cohorts. The main aetiologies of TSS are spinal degenerative changes and heterotopic ossification, and patients with developmental spinal stenosis, ligament ossification, and spinal stenosis at any region are at an increased risk of developing TSS. The diagnosis of TSS is challenging. The clinical presentation of TSS could be complex, concealed, or severe, and these features may be confusing to clinicians, resulting in an incomplete or delayed diagnosis. Additionally, a consolidated diagnostic criterion for TSS is urgently required to improve consistency across studies and form a basis for establishing treatment guidelines. The optimal treatment option for TSS is still under debate; areas of controversies include choice of the decompression range, choice between simultaneous or staged surgical patterns, and the order of the surgeries. The present study reviews publications on TSS, consolidates current awareness on prevalence, aetiologies, potential risk factors, diagnostic dilemmas and criteria, and surgical strategies based on TSS subtypes. This is the first review to include thoracic spinal stenosis as a candidate disorder in TSS and aims at providing the readers with a comprehensive overview of TSS.

Keywords: diagnosis criteria; surgery; tandem spinal stenosis.

Figure 1

The representative MRI of the subtypes of TSS. The whole spine MRI of a CLTSS patient shows CSS at C4-7 (A1, arrows) and LSS at L3-4 (A3, arrows); In the MRI of a CTTSS patient, extensive hypertrophy of posterior longitudinal ligament causes CSS (B1, arrows) and ThSS (B2, arrows), the stenotic change affects C4-T5 (B1, 2); In the MRI of a TLTSS patient, T3-5 ThSS (C2, arrows) and L2-S1 LSS (C3, arrows) occurs concomitantly; A CTLTSS patient has concurrent C2-6 CSS (D1, arrows), T4-5, T10-12 ThSS (D2, arrows), and L2-S1 LSS (D3, arrows), which are caused by heterotopic ossification and degeneration changes (D1-3). CSS, cervical spinal stenosis; CLTSS, cervico-lumbar tandem spinal stenosis; CTTSS, cervico-thoracic tandem spinal stenosis; CTLTSS, cervico-thoraco-lumbar tandem spinal stenosis; LSS, lumbar spinal stenosis; TSS, tandem spinal stenosis; ThSS, thoracic spinal stenosis; TLTSS, thoraco-lumbar tandem spinal stenosis.

Figure 2

The treatment algorithm of the subtypes of TSS. For CLTSS, the main determinants of surgical pattern are predominant symptoms, complication rate, and general condition; while lesion distance alters the surgical pattern greatly in the other TSS subtypes with ThSS. The surgical sequence is determined by the predominant symptoms and subjective examination results. CSS, cervical spinal stenosis; CLTSS, cervico-lumbar tandem spinal stenosis; CTTSS, cervico-thoracic tandem spinal stenosis; CTLTSS, cervico-thoraco-lumbar tandem spinal stenosis; LSS, lumbar spinal stenosis; TSS, tandem spinal stenosis; ThSS, thoracic spinal stenosis; TLTSS, thoraco-lumbar tandem spinal stenosis.