The co-existence of cervical and lumbar canal stenosis was seen in 62 cases (88.57%) out of our 70 cases. Although literature stated the exact percentage is ranging from 5 to 25% [3, 5, 8], our results agreed with Matsumoto et al.  who discovered that positive degenerative MRI findings in both the lumbar and cervical spine was observed in 78.7% of the patients; Kikuike et al.  stated that the incidence of this pathologic condition has been reported to range from 0.12 to 19%. Dagi et al.  concluded that the calculated prevalence of degenerative spine disease, including tandem spinal stenosis (TSS), is higher in the radiological than in the surgical literature. Radiographic signs of degenerative cervical and lumbar spondylotic changes can be seen in 50% of the population over the age of 50 years and 75% over the age of 64 years. Aydogan et al.  thought that the overall proportion of patients with combined complaints of cervical and lumbar spine stenosis was 3.4% among 230 patients.
In a series of 12 patients with cervical spondylosis reported by Teng and Papatheodorou , seven had TSS. Four of the 12 patients were asymptomatic, but seven underwent decompression at both levels. Epstein et al.  reported that 5% of patients with spondylotic disease presented with symptoms referable to both the lumbar and the cervical portions of the spine.
Dagi et al.  stated that 19 of 100 patients admitted with a diagnosis of cervical or lumbar stenosis were found to have TSS. This variation in incidence may be a function of patient selection or of the small number in each series.
Cases with symptomatic cervical canal stenosis were 30 (42.857%), cases with asymptomatic cervical canal stenosis were 32 (45.71%), and cases with no cervical symptoms were 8 (11.4%). Epstein et al. and Dagi et al. [11, 14] concluded that four out of the 30 patients admitted for symptomatic lumbar canal stenosis had clinical signs of cervical myelopathy. And 9 out of the 30 patients admitted for lumbar canal stenosis had radiological cervical canal stenosis. Matsumoto et al.  concluded that MR images from asymptomatic subjects frequently showed degenerative changes in the lumbar spine, and these changes were significantly associated with degeneration in the cervical spine, suggesting that disk degeneration occurs in tandem in the lumbar and cervical spine.
As regards concomitant diseases, we had two cases known to be rheumatic (2.8%). Dagi et al.  also noted the presence of osteoarthritis in 16% and one patient had mild rheumatoid arthritis, but the limited records of patients with rheumatic disease hinders finding the actual association of these group of diseases in canal stenosis patient because they usually present with bony and joint pains that mimic degenerative canal stenosis symptoms.
As concluded by Felbaum et al.  when they stated that cervical decompression alone only may provide clinically significant relief of these lumbar symptoms and Epstein et al.  performed cervical decompression only in 12 patients with both cervical and lumbar canal stenosis. Post-operatively, they all showed improvement of both symptoms.
Also Aydogan et al.  stated that the treatment plan should be designed according to the chief complaints and symptoms of the patient. The operation should also be staged as it eliminates the risks of same-day surgery in patients which typically have an advanced age and comorbidities prior to surgery.
Two patients only underwent lumbar decompressive surgery before cervical decompression and they showed modest improvement because they were associated with absolute cervical canal stenosis, with the need for another surgery for cervical decompression .
Epstein et al.  performed lumbar decompression to 9 cases with both cervical and lumbar symptoms; post-operatively, the patient showed improvement of lumbar stenosis symptoms and worsening of cervical symptoms, and Yamada et al.  stated that radiographic coexisting cervical stenosis did not affect surgical outcomes for lumbar stenosis, although symptomatic cervical lesion affected the neurological score after lumbar surgery. An additional surgery for cervical lesion significantly improved neurological findings in tandem spinal stenosis (TSS) patients.
Krishnan et al.  recommend one-stage surgery for patients below the age of 60 while staged surgery is recommended in patients above the age of 60 years. Naderi and Mertol  concluded that simultaneous surgery for different segments of the spine is an alternative approach in patients with combined symptomatic pathologies, whose general or social condition is risky for two long-lasting procedures. This fact is also agreed with Epstein et al.’s  conclusion; they stated that the clinical outcomes of 1-staged combined cervical and lumbar decompression (CCLD), measured by JOA score for cervical myelopathy and low back pain and by activities of daily life (ADL), improved significantly at 6 months post-operatively. These effects were maintained for an average of 69 months in 10 patients suggesting that CCLD may be indicated for elderly patients, because of its potential benefits of minimum hospital stay and reduced costs . Although other authors such as Kikuike et al.  have reached opposite conclusion, still there are no enough evidence about the pros and cons of the one-staged combined surgery because larger numbers of patients are necessary to provide sufficient data.
Aydogan et al.  concluded that the treatment plan should be designed according to the chief complaints and symptoms of the patient. The operation should also be staged. Staged surgery eliminates the risks of same-day surgery in patient who typically have an advanced age and comorbidities prior to surgery.
In our study, we discovered that the number of patients having both cervical and lumbar canal stenosis is much higher than proven in the literature. Out of 70 patients, we had 62 patients (88%) with concomitant cervical and lumbar canal stenosis, and 33 patients whose plan of management has been changed from doing lumbar decompressive surgery to cervical decompressive surgeries either alone, preceding lumbar decompression, or together in a single-staged surgery.
Dagi et al.  stated that the calculated prevalence of degenerative spine disease including TSS is higher in the radiological than in the surgical literature. Radiographic signs of degenerative cervical and lumbar spondylotic changes can be seen in 50% of the population over the age of 50 years and 75% over the age of 64 years.
Caron and Bell  stated that the exact frequency of symptomatic tandem stenosis is unknown, since only a small percentage of patients presenting with either cervical or lumbar stenosis have imaging studies of both the lumbar and the cervical spine. Furthermore, asymptomatic radiographic cervical or lumbar neural compression can be seen in a large percentage of the population.
Matsumoto et al.  concluded that MR images of asymptomatic patients with degenerative changes in the lumbar spine, and these changes were significantly associated with degeneration in the cervical spine, suggesting that disk degeneration occurs in tandem in the lumbar and cervical spine.
Krishnan et al.  stated that though TSS occurs relatively infrequently, the unrecognized occurrence in the general population may be higher. Detailed examination for even subtle signs followed by whole spine MRI (T2 sagittal) screening should be done. Lebl et al.  also stated that tandem stenosis should be considered when evaluating a patient with mixed claudication and myeloradiculopathy symptoms.
Problems may arise when the associated cervical stenosis is asymptomatic as it may lead to deficits or paraplegia after non-cervical spine surgery because it is asymptomatic stenosis; there is no clinical reason to obtain radiographic studies. And one can have severe radiographic stenosis without any symptoms. Krishnan et al.  stated that failure to detect cervical stenosis in a patient presenting predominantly with lumbar stenosis may carry significant risk of injury to the cervical cord during positioning for lumbar decompression surgery.
There are reports of missed compressive lesions of the spinal cord at the cervical region in lumbar degenerative disease [1, 3, 19].
According to the site of stenosis, the narrowing of the spinal canal may cause spinal cord and/or nerve root compression. The problem of missing a cervical lesion arises from dynamic mechanical factors of the cervical spine because as the neck extends, ligamentum flavum buckles inwards which results in the greatest decrease in the cross sectional area in the cervical canal as well as the spinal cord shortens and its cross sectional area increases which in turn increases the risk of cervical spondylotic myelopathy (CSM) [1, 5].
Aydogan et al.  stated that the treatment plan should be designed according to the chief complaints and symptoms of the patient. Yamada et al.  concluded that a clearly defined surgical algorithm does not exist and it remains unknown which procedure is more effective for achieving post-operative neurologic improvement in TSS patients with myelopathy.