3.1 Study selection
After duplicate removal, 440 articles were screened. Based on the title and abstract, the authors excluded 179 and 103 papers respectively. Of 158 articles, 28 were not possible to retrieve. Finally, 101 studies were removed due to incompatibility with our eligibility criteria.
3.2 Study synthesis
A total of 776 patients were evaluated. Mean M/F ratio was 24.08 and weighted arithmetic mean age was 17,68 years old. 516 patients underwent surgical treatment (anterior cervical discectomy or corpectomy and fusion, posterior arthrodesis, cervical duraplasty, posterior decompression with coagulation of epidural venous plexus, anterior cervical fusion). 242 patients were treated conservatively with cervical collar and, in some cases [28] physical rehabilitation on affected extremities and neuroprotective drugs [8]. 18 patients did not undergo neither surgical nor conservative treatment [23].
Sum of characteristic
|
|
N° of Patients
|
776
|
M/F ratio
|
24.08
|
Mean Age
|
17.68
|
Treatment modality
|
516 (surgical) / 242 (conservative)
|
Parameters analyzed
|
Strength, disease progression, sagittal balance, clinical data, radiological data, electrophysiological data
|
Table 1. Sum of characteristics of patients involved in systematic review table
In each treatment group, the outcome improvement rate was analyzed in different terms. In fact, outcome was meant in 6 different domains: strength, disease progression, sagittal balance, clinical data (such as GOEL score, VAS, mJOA, ADL disability, Odom scale), general radiological data, electrophysiological data. For each of these items, rate of improvement after treatment was analyzed. “Other radiological data” include parameters measured in MRI (involving spinal cord and/or spinal canal, evaluated in standard or extension position, even intensity of activation of M1 cortex) that could be related to an improvement in symptoms. This entity differs from “Sagittal balance”, which include only radiographic parameter (C2-7 CL angle, T1 slope, cervical tilt angle etc.) concerning the correct alignment of cervical spine.
Dealing with the surgical group, an evident improvement of strength was registered (96 out of 116, 82,7%), concerning grip strength and MRC score in upper limbs. Among clinical data, VAS was considered just in one patient of one study [12] showing an improvement (from preoperative 3 to preoperative 1). In general, clinical data (or questionnaire) improved in 250 of 298 patients (83,8%) who underwent surgical treatment. Furthermore, surgical treatment was shown to arrest the disease in 5 out of 5 patients (100%). Sagittal balance and general radiological data improved in 60 out of 112 (53,5%) and 90 out of 110 patients (81,8%), respectively. Electrophysiological data were registered in 3 studies [10, 28, 38, 39] in our review and showed an improvement of 54 out of 62 (99,3%) surgery group patients.
Conservative treatment obtained an improvement of 20% in grip strength (one patient out of 5 in the two studies in which grip strength was evaluated after conservative treatment). After conservative treatment, there was an improvement of 0% of clinical data (out of 49 patients), and most of the patients remain stable during FU. On the other hand, there was a rate of halting disease progression in 87,7% (172 out of 196). Other radiological data was evaluated just in one study Tashiro (32 out of 56; 57,1%, an indirect data). Sagittal balance was not evaluated in any study in which conservative treatment was advocated. Notably enough, just in one study was evaluated a “no treatment cohort”, in which there was a 0% improvement of electrophysiological data.
We have to say that the main parameter considered in “conservative treatment group” was disease progression, with minimal improvement of other items. In fact, few studies of conservative group took into account other clinical (i.e. grip strength, clinical score, electrophysiological data) or radiological parameters, thus reducing its statistical significance.
parameters
|
surgical group
|
conservative group
|
Strength
|
82,7%
|
20%
|
diseade progression
|
100%
|
87,7%
|
clinical improvement
|
83,8%
|
0%
|
sagittal balance
|
53,5%
|
N/A
|
radiological data
|
81,68%
|
57,1%
|
electrophysiological data
|
99,3%
|
N/A%
|
Table 2. Percentage of improvements obtained in the different parameters analyzed, comparing surgical vs conservative treatment. N/A: Not Analyzed
3.3 Meta-analysis results
The overall pooled success rate for clinical assessment was 84%, with 95%CI: 65%-98%. It was higher for surgically treated patients (92%, 95%CI: 84%-98%)) than for medically treated patients (78%, 95%CI: 32%-100%) (Figure 1). Based on radiological outcome, the overall pooled success rate was the same 88% with 95%CI: 67%-100%. It was higher for surgically treated patients (91%, 95%CI: 68%-100%)) than for the unique study reporting this outcome on medical treatment (57%, 95%CI: 43%-70%) (Figure 2).
Figure 2. Forest plot of the estimated success rate based on clinical assessment, stratified by treatment (surgical vs medical)
3.3 Study overview
Two main domains were considered in our systematic review: clinical data (grip strenght, VAS, clinical questionnaire, electrophysiological data, disease progression), and radiological data (i.e., sagittal balance and others).
Grip strength of the upper extremities is one of the most common clinical factors analyzed in HD literature as part of post-operative outcome. The upper limbs extremities strength was improved in different studies [14, 28], as well as dysesthesia in the same areas [28]. Generally, the grip strength continuously increased within 6 months after surgery, stopping 1 year after the surgery (as demonstrated by Hong-Li Wang's 2021 working group [21]). Among clinical data, VAS was evaluated just in one study and was demonstrated an increasing after posterior arthrodesis [12]. Overall recovery was found to be correlated to clinical factors like age of HD onset, duration of disease, and presence of physiologic/pathologic reflexes, among others.[18].
Figure 3. Forest plot of the estimated success rate based on radiological assessment, stratified by treatment (surgical vs medical)
Radiological improvement was evaluated in term of sagittal balance and volume of the spinal cord on MRI , but also encompassed brain fMRI activation of cortical motor area [21].
Indeed, post-operative antero-posterior diameters of the spinal canal significantly increased in the flexed neck position [14, 24]. Concerning X ray- evaluated sagittal balance, a significative statical correlation between surgical outcome and Cobb Angle – CGH-C2 SVE were demonstrated [16]. Therefore, surgical treatment was related to a significant increase of cervical lordosis [22].
Concerning conservative treatment, one domain was most considered: disease progression [8, 13, 26, 35]. In a variable range of time, disease seemed to stop in most cases after the patient wore a cervical collar.
As the Forest plots show above, the success rate of surgical treatment in terms of clinical outcome is 92%, compared to 78% of conservative treatment. On the other hands, surgical and conservative treatment showed radiological improvement outcome rate in 91% and 57%, respectively. Few data are available in literature regarding clinical and radiological outcome in conservative treatment patients. Among them, disease progression was the main parameter under examination,, among clinical data, concerning conservative treatment. On the other hand, grip strength, clinical questionnaire, electrophysiological data were available to consider after surgical treatment in a wider cohort.