Tandem Stenosis: Fix the Cervical Spine or Lumbar Spine First?

Shay Bess

BACKGROUND DATA

Tandem spinal stenosis (TSS) is defined as concomitant stenosis in the cervical and lumbar spine. However, rather than simply designating a radiographic phenomenon, TSS should be used to denote a complex syndrome that reflects symptomatic neural compression in the cervical and lumbar spine. Dagi et al. (1) defined TSS as a triad of (a) intermittent neurogenic claudication, (b) complex gait disturbance, and (c) mixed pattern of upper and lower motor neuron signs in the upper and lower extremities due to coexistant myelopathy and polyradiculopathy at the cervical and lumbar levels. This mixed clinical presentation, due to combined cervical and lumbar stenosis, often confounds an accurate diagnosis. Another factor leading to missed or delayed diagnosis among patients with TSS is that patients often have symptoms and physical findings that are predominately referable to only the cervical or lumbar spine (2). Consequently, the true incidence and prevalence of TSS is most likely inaccurate due to underdiagnosis. This is reflected by the variable prevalence reported in literature. LaBan and Green (3) reported that 54 of 460, 964 patients (0.12% incidence) admitted to a tertiary care center over a 10-year period were diagnosed with TSS. Epstein et al. (2) estimated that approximately 5% of patients with symptomatic cervical or lumbar stenosis actually have mixed symptoms due to TSS. However, Dagi et al. (1) indicted that TSS is more common, as the authors reported a 19% incidence of TSS (19 of 100 patients) among patients evaluated for cervical or lumbar stenosis over a 5-year period. More recently, Lee et al. (4) evaluated 440 cadaveric spines and found that the prevalence of TSS varies from 0.9% to 5.4%, depending upon the definition used for spinal stenosis. By direct measurement on the cadaveric spines, 95 of the 440 skeletons (21.5%) had at least one level of cervical stenosis (defined as spinal canal measuring <12mm) and 74 of the 440 skeletons (16.8%) had at least one level of lumbar stenosis. The prevalence of TSS was 5.4% (24 of 440). When correcting for radiographic magnification (the authors extrapolated the cadaveric measurements used in the study to a radiographic definition of spinal stenosis of 12mm), the prevalence of stenosis was reduced to 5.4% in the cervical spine (24 of 440) and 5.9% in the lumbar spine (26 of 440), and the overall prevalence of TSS was 0.9% (4/440). Importantly, the authors reported that the presence of stenosis in one spinal region was predictive of stenosis in another region.

Based upon the anatomic data, lumbar stenosis had a positive predictive value of 32.4% (24/74) for the presence of cervical stenosis, and cervical stenosis had a positive predictive value of 25.3% (24/95) for lumbar stenosis. When extrapolating the cadaveric measurements to radiographic values, lumbar stenosis had a positive predictive value of 15.3% (4/26) for the presence of cervical stenosis, and cervical stenosis had a positive predictive value of 16.7% (4/24) for lumbar stenosis. The prevalence of cervical stenosis in specimens with lumbar stenosis group was significantly higher than the prevalence of cervical stenosis in the specimens without lumbar stenosis. Likewise, prevalence of lumbar stenosis was significantly higher in the specimens with cervical stenosis compared to specimens without cervical stenosis. The authors acknowledged that the prevalence of TSS is likely greater than can be ascertained by skeletal evaluation because the soft tissue component of spinal stenosis cannot be delineated. This important study underscores the need for clinical diligence to search for TSS in patients with regional spinal stenosis due to the relatively high prevalence of TSS and the positive predictive value for TSS when either cervical or lumbar stenosis is diagnosed.

Another factor confounding the diagnosis and treatment of TSS is that treatment of a single spinal region often unmasks the region of secondary compression, generating a new set of postoperative symptoms. For example, a patient treated for what was initially believed to be isolated cervical compression may postoperatively manifest neurogenic claudication due to the patient’s underlying lumbar spinal stenosis (LSS). Physicians not suspecting the diagnosis of TSS may be confused by these new symptoms and erroneously search for other causes such as demyelinating disorders, neoplasia, or incomplete treatment at
the initial site. This phenomenon also occurs in patients whose treatment is delayed, as new symptoms may emerge that are referable to the region of secondary compression. Again, these new symptoms often compound the patient’s initial symptoms, generating a confusing clinical picture as the patient deteriorates. Epstein et al. (2) reported that 8 of 11 patients with TSS who received initial cervical decompression required secondary lumbar decompression, and 4 of 13 patients receiving initial lumbar decompression required a secondary cervical decompression. Consequently, the possibility of concomitant cervical and lumbar stenosis must be considered when initially evaluating patients for spinal stenosis, and the diagnosis of TSS should be considered in patients with new or worsening symptoms following isolated treatment for cervical or lumbar stenosis.

PRESENTING SYMPTOMS

Currently, no classification scheme exists for TSS. However, the mixed presentation of TSS can be elucidated by separately considering the signs and symptoms of cervical spinal stenosis (CSS) and LSS. The diagnosis and treatment of CSS and cervical spondylotic myelopathy (CSM) is more completely discussed elsewhere in this text; however, the classic symptoms of early CSM include abnormal hand sensation, impairment of fine motor skills in the hands, and difficulty with balance and gait (5,6). As the disease progresses, gait deterioration most often parallels the severity of CSM and is more often a result of lower extremity spasticity, consistent with upper motor neuron symptoms, rather than lower extremity weakness. The progression and severity of CSM are well demonstrated by the Nurick and Japanese Orthopaedic Association (JOA) grading scales (Tables 142.1 and 142.2).

By comparison, symptoms of neurogenic claudication due to LSS include buttock and dorsal leg pain, leg cramping, and leg paresthesias and/or weakness that appears with physical activities combined with lumbar extension. Symptoms are relieved by rest combined with lumbar flexion (7,8). Lumbar extension decreases the spinal canal crosssectional area; therefore, static, baseline spinal stenosis is exacerbated by lumbar extension. Symptoms are relieved by flexing the lumbar spine because flexion increases the space available for the cauda equina and nerve roots. Classically, patient activities are accommodated by assuming a flexed lumbar posture. Therefore, patients report ambulation with lumbar flexion using aids (shopping cart, walker, wheelchair), walking uphill (lumbar flexion) easier than downhill (lumbar extension), and exercise using a bicycle (lumbar flexion) easier than upright activities (lumbar extension). Bladder symptoms due to autonomic sphincter dysfunction are uncommon in LSS, occurring in approximately 10% of patients with severe LSS. The severity and outcomes for LSS treatment can be assessed using the Zurich Claudication Questionnaire (Table 142.3).

TABLE 142.1 Nurick Classification Scheme for Cervical Myelopathy

Grade	Root Signs	Cord Involvement	Gait	Employment
0	Yes	No	Normal	Possible
I	Yes	Yes	Normal	Possible
II	Yes	Yes	Mild abnormality	Possible
III	Yes	Yes	Severe abnormality	Impossible
IV	Yes	Yes	Only with assistance	Impossible
Adapted from Nurick S. The pathogenesis of spinal cord disorder associated with cervical spondylosis. Brain 1972;95:87-100.

TABLE 142.2 The Japanese Orthopaedic Association Scale: An Objective Assessment Scale Quantitating the Severity of the Spondylotic Myelopathy Based on Four Categories

Upper extremity function
	0 = impossible to eat with chopsticks or spoon 1 = possible to eat with spoon but not with chopsticks 2 = possible to eat with chopsticks but inadequate 3 = possible to eat with chopsticks but awkward 4 = normal
Lower extremity function
	0 = impossible to walk 1 = need cane or aid on flat ground 2 = need cane or aid only on stairs 3 = possible to walk without cane or aid but slow 4 = normal
Sensory
	Upper extremity
		0 = apparent sensory loss 1 = minimal sensory loss 2 = normal
	Lower extremity
		Same as upper extremity
	Trunk
		Same as upper extremity
Bladder function
	0 = complete retention 1 = sever disturbance (inadequate evacuation, straining, or dribbling of urine) 2 = mild disturbance (urinary frequency, urinary hesitancy) 3 = normal
Maximum score = 17 points
Adapted from Hirabayashi K, et al. Operative results and postoperative progression of ossification among patients with ossification of cervical posterior longitudinal ligament. Spine 1981;6:354-364.

TABLE 142.3 Zurich Claudication Questionnaire

Symptom severity scale
1. The pain you have had on average including the pain in your back, buttocks, and pain that goes down your legs:
	□ Very severe □ Severe □ Moderate □ Mild □None
2. How often have you had back, buttock, or leg pain?
	□Every minute of the day □Everyday for most of the day □ Everyday, for at least a few minutes □ At least once a week □ Less than once a week
3. The pain in your back or buttocks?
	□Very severe □ Severe □ Moderate □ Mild □ None
4. The pain in your legs or feet?
	□Very severe □ Severe □ Moderate □ Mild □ None
5. Numbness or tingling in your legs or feet?
	□Very severe □ Severe □ Moderate □ Mild □ None
6. Weakness in your legs or feet?
	□Very severe □ Severe □ Moderate □ Mild □ None
7. Problems with your balance?
	□Yes, often I feel my balance is off, or that I’m not sure-footed □ Yes, sometimes I feel my balance is off, or that I’m not sure-footed □ No, I have had no problems with balance
Physical function scale
8. How far have you been able to walk?
	□<50 feet □ Over 50 feet, but <2 blocks □ Over 2 blocks, but <2 miles □ Over 2 miles
9. Have you taken walks outdoors or in malls?
	□No □ Yes, but always with pain □ Yes, but sometimes with pain □ Yes, comfortably
10. Have you been shopping for groceries or other items?
	□No □ Yes, but always with pain □ Yes, but sometimes with pain □ Yes, comfortably
11. Have you walked around the different rooms in your house or apartment?
	□No □ Yes, but always with pain □ Yes, but sometimes with pain □ Yes, comfortably
12. Have you walked from your bedroom to the bathroom?
	□No □ Yes, but always with pain □ Yes, but sometimes with pain □ Yes, comfortably
Adapted from Stucki G, et al. Measurement properties of a self-administered outcome measure in lumbar spinal stenosis. Spine 1996;21:796-803.