One-staged combined decompression for the patients with cervico-thoracic tandem spinal stenosis

Spinal stenosis is an age-associated disease and can sometimes involve more than one spinal segment, a situation which is termed as tandem spinal stenosis (TSS) [1, 2]. Occasionally, symptomatic cervico-lumbar and cervico-thoracic TSS were reported in previous publications, within which the results of different surgical approaches were described [1, 3–6]. Generally, cervico-lumbar TSS is related to the spondylotic proliferation and disc herniation, while cervico-thoracic TSS is more likely to result from ectopic ossification and bulking of ligaments inside the spinal canal, namely ossification of posterior longitudinal ligament (OPLL) and ligamentum flavum (OLF) [4, 5]. Similar to cervico-lumbar TSS, two surgical strategies are available for the cervico-thoracic TSS, which are one-staged and two-staged decompressions. One-staged combined decompression seems more attractive due to the potential benefits of single hospitalization and single anesthetic procedure. Chen et al. [5] did the pioneering research for one-staged surgery in 15 patients with cervico-thoracic TSS, and regarded it as an aggressive surgical strategy. They have emphasized on the preoperative communication with patients on the impact of perioperative complications and postoperative consequences on its outcome. The surgical maneuvers and/or approaches were diverse in the study by Chen et al., for example, both anterior and posterior approaches for cervical spine were used. In this study, we report the clinical outcomes of one-staged combined decompression via a single posterior incision, which could be regarded as an attempt to simplify the procedure.

Previous publications sporadically reported a rare clinical situation, in which symptomatic cervical and thoracic TSS simultaneously occurred [4, 5, 9]. In these reports, two surgical strategies were mentioned, namely one-staged and two-staged decompressions. However, descriptions and discussions on either approach is scarce. Therefore, more research-based evidence is necessary in order to establish a rational treatment algorithm for this pathology. In our center, 16 subjects were treated through one-staged decompression via a single posterior incision, and the main surgical manipulations were slightly different from what has been reported by Chen et al. [5].

The benefits of combined decompression are apparent, one hospitalization and one anesthesia as well as lesser medical cost, and more encouragingly, the studies on combined cervico-lumbar decompression have proven that its clinical outcomes is comparable with staged decompression [3, 6, 10]. However, it was unclear whether it is equally applicable for cervico-thoracic TSS. This study found that the postoperative courses after combined cervico-thoracic decompression were quite eventful, even though all the operations were performed by experienced surgeons. Previous publications reported that in about 30 % of patients who had undergone thoracic decompression could develop postoperative neurological deterioration [7, 9–15]. It is rather alarming that 37.5 % of the subjects in the present stud y suffered immediate postoperative neurological deterioration (Table 2). In fact, we were very careful on the selection of subjects and also made some modifications on surgical techniques to decrease duration of the surgery and blood loss (see “Materials and methods” section). For example, we chose ODL instead of anterior corpectomy with fusion (ACF) for cervical decompression, in order to avoid repositioning the patients and making another incision and manipulative tunnel, hoping to minimize the alteration of the spinal alignment during the operation, which could cause severe damage to the already debilitated spinal cord [14]. Urgent MRI scans were arranged for all deteriorated subjects but no remaining or new emerging compression were found. Thus, no rescue surgery was needed during the hospitalization, such as anterior decompression.

This study found that blood loss was significantly increased for the patients with postoperative neurologic deterioration (Table 2). We speculated that the main reason for massive blood loss was the prolonged operated segments in the deteriorated patients (Table 2). Besides, four of the deteriorated patients underwent CD. This procedure was performed with an extensive removal of spinal elements; so it was often accompanied with more blood loss [7, 15]. However, within the first year after the surgery, five deteriorated subjects improved to a level better than the preoperative neurologic status simply through conservative treatments (Fig. 2). This was an intriguing finding, implying that deterioration resulting from massive blood loss might have a more favorable prognosis than that from incomplete decompression, and this speculation well deserves a specific and comprehensive assessment by further studies. Another noticeable finding was that all of four subjects, who received thoracic decompression again 9 months to 3 years after the combined decompression, achieved postoperative neurological improvement. Though the relapse of walking inability mainly resulted from the continuing growth of thoracic ossified ligaments, as their imaging examinations revealed (Fig. 3), this phenomenon also could be interpreted as the reflection of a paradox, how to secure the sufficient decompression for all affected segments while minimizing blood loss and the area manipulating. For example, we tended to be very careful when scheming and deciding the CD levels for thoracic decompression, though CD was found to have a favorable late neurological recovery (Fig. 5).

Other unfavorable aspect of combined decompression is the high incidence of CSF leakage (62.5 %) (Table 3). Previous publications reported that OPLL was the greatest risk factor for CSF leakage and more than one third of the patients with thoracic decompression would develop this complication [7, 15–17]. Therefore, we attributed the high incidence of CSF leakage in our study to the ossified ligaments and expansive surgical areas. We adopted a set of treatment strategies for CSF leaks, including intraoperative repair of the dural tears using fibrin glue, gelfoam and artificial dura, followed by flat bedrest and compressive dressing after the removal of drainage during the postoperative hospitalization. Though previous studies demonstrated that CSF leakage did not affect the long-term clinical outcomes [16, 18], some postoperative complications, including neurological deterioration, were prone to occur in the subjects with CSF leakage, for example infection and PTE. Besides, our study found that the neurological improvement predominantly occurred in the first and/or second year after this procedure (Fig. 2), and afterwards a few subjects presented with relapse of walking problems. The reoccurrence of neurological symptoms seemed earlier than reported by Chiba et al. [19] in patients with cervical myelopathy. This phenomenon, as aforementioned, was mainly related to the smaller spinal canal at the thoracic spine and more importantly, the progression of asymptomatic ossified ligaments at other thoracic segments, which was also the predominant reason for the high rate of reoperation in this study (Fig. 3).

The limits of this study were the small size of the cohort and absence of the comparison with patients who underwent two-staged decompression. Therefore, more studies on both surgical strategies are required to establish an effective surgical algorithm for cervico-thoracic TSS.

This study reported the clinical outcomes of one-staged combined decompression for cervical and thoracic TSS, and elaborately described the complications associated with this procedure. Though this procedure had a fair final neurological outcomes, considering the involvement of thoracic decompression in this entity, its postoperative course was frequently complicated with undesirable events, especially instant neurological deterioration and CSF leakage. Therefore, spinal surgeons should be very cautious while performing this invasive surgical procedure.