Evaluation and Treatment of Tandem Spinal Stenosis

Joseph F. Baker, MCh, FRCSI

Disclosures

J Am Acad Orthop Surg. 2020;28(6):229-239. 

In This Article

Evaluation

The presentation of TSS includes symptoms attributable to the levels of stenosis, and therefore, a mixture of myelopathy, radiculopathy, and classic neurogenic claudication is possible depending on whether the cervical, thoracic, and/or lumbar spine are involved. Presenting features can mimic amyotrophic lateral sclerosis and other forms of motor neuron disease.[13,14] Mixed upper and lower motor neuron symptoms and signs may be evident. A comprehensive history and examination are therefore essential to reduce the risk of missing a noncontiguous stenosis that can present catastrophically in a delayed fashion if not detected.[15,16]

History

A detailed and accurate history sets the scene before clinical examination. The classic triad encountered in TSS includes intermittent claudication, gait disturbance, and mixed upper and lower extremity symptoms.[13,17] Based on information gleaned from the patient, often one can determine the likely pathoanatomy—when subsequent clinical examination findings are not in keeping with what is expected based on history, then stenosis at a remote level must be suspected.

Upper motor neuron (UMN) symptoms may be blunted, or completely masked, by the presence of stenosis in the lumbar spine. Similarly, UMN symptoms may be the dominant feature, despite the patients presenting complaint and history being suggestive of lumbar stenosis (Figure 1).[18] Particular difficulty may be encountered when stenosis affects lumbar and low thoracic levels simultaneously—stenosis at the level of the conus can result in lower extremity symptoms very similar to those expected in LSS.[16]

Figure 1.

T2-weighted sagittal (A) and axial (B) images of the cervical spine and sagittal (C) and axial (D) images of the lumbar spine. Axial images of the most stenotic segments. A 68-year-old woman initially referred with cervical radiculopathy and imbalance and cervical spine imaging. On the basis of clinical examination that revealed diminished reflexes, additional imaging of the lumbar spine was requested, confirming the presence of LSS. LSS = lumbar spinal stenosis

Patients with stenosis in the cervical spine may present with symptoms of myelopathy with or without features of radiculopathy. Complaints of loss of manual dexterity and balance are classic features of cervical myelopathy, whereas with stenosis in the thoracic spine one would not expect loss of upper extremity function—a potential indication to the level of disease. Collateral history from family members, particularly in the older, frailer patient, is useful because patients may be either unaware of symptom progression and severity or even stoically downplay symptoms. Sphincter disturbance involving with the bladder, bowel, or both must also be inquired later, and although likely often overlooked, sexual function should be documented. In a series of 30 patients suffering from stenosis affecting the cervical and thoracic region simultaneously, Hu et al[2] noted that 17 presented with urinary symptoms.

In the lumbar spine, below the level of the conus, stenosis will result in symptoms secondary to lower motor neuron dysfunction. Pain, numbness, and/or weakness in a single or multiple nerve root distribution is possible. Reduced walking distance, or claudication, is typical, but the reason for stopping must be elucidated to detect other nonspinal causes, for example, vascular claudication. Relieving factors should be noted—patients suffering from spinal claudication classically gain relief and increase their walking time and/or distance by the use of a walking aid or shopping trolley. The forward-flexed posture allows the lumbar spine to increase its internal diameter, whereas the external aid prevents loss of balance. Peripheral neuropathy is a common concomitant disease in the elderly—questions should help determine whether lower extremity symptoms may reflect a stocking distribution and consideration then given to potential causes such as diabetes mellitus or vitamin B12 deficiency.

Symptom duration must be established—duration of LSS symptoms is a potential predictor for the presence of cervical and/or thoracic stenosis and has been linked to the outcome of surgery with long-standing disease being associated with less improvement after surgery.[13,17,19] Gupta et al[20] noted, even in a relatively small cohort of patients undergoing simultaneous thoracic and lumbar decompression, that functional gains were inversely proportional to the duration of symptoms.

A detailed medical history will help guide treatment decisions. Particular focus is needed on medical conditions, such as cardiac and respiratory, that may predispose the individual to greater surgical risk—comorbid status may influence treatment strategy, whether surgical or nonsurgical, and, if surgical, whether simultaneous or staged surgery.

Clinical Examination

Clinical examination should seek out both upper and lower motor neuron signs that can be attributed to the three regions of the spinal column. The findings for cervical myelopathy are well described: the presence of upper hyperreflexia and myelopathy hand signs, including Hoffman's reflex, the inverted radial reflex, and the finger escape sign, is easily tested for.[21,22] In the lower extremities, one can expect to encounter hyperreflexia, an upgoing plantar reflex and (sustained) clonus. Having the patient stand and walk in the consult room will allow performing the Romberg test, may unearth gait disturbance, and may assist the clinician in evaluating effectiveness of any mobility aid. A timed up-and-go test is a simple and useful adjunct to assess physical conditioning and muscle strength. One must use caution when the clinical examination does not support a classic history of myelopathy, as 21% of patients may not demonstrate the anticipated clinical examination findings.[21]

In patients with suspected cervical stenosis, assessing the range of motion comfortably achieved is useful to record—this may also aid the anesthesiologist who will have to intubate and needs to know the safe arc within which the patient is comfortable and beyond which one assumes that their spinal cord is at risk. This information may also be useful to the orthotist if the patient at all needs a cervical orthosis during their treatment pathway.

In stenosis in the lumbar region, lower motor neuron signs are expected to predominate including wasting, altered sensation, diminished or absent reflexes, and weakness. Clinical examination findings and their relevance are summarized in Table 2. The presence of severe canal stenosis in the lumbar spine may attenuate expected UMN signs when cervical or thoracic cord compromise is also present. In one series of 50 patients with thoracic stenosis presenting with myelopathy, hyperreflexia of the knee and ankle was detected in 48% and 28%, respectively, whereas a positive Babinski was noted in 28%—the proportion of patients with hyperreflexia at the ankle and a positive Babinski lower in those with concomitant LSS (Table 3).[18]

Radiographic Investigation

Imaging is one of the key considerations when evaluating patients for spinal pathology. Radiographs are often the first modality used and will give an indication as the presence or absence of degenerative disease as well as sagittal canal dimensions—the Torg-Pavlov ratio may be easily measured. Erect, full-spine radiography is useful for determining alignment parameters and facilitating surgical planning.

Advanced imaging, most frequently MRI, is essential, and most salient details will be captured with this modality. CT may be used for surgical planning, defining extent of OPLL or OLF, or used with myelography if a patient is unable to have an MRI for any reason.

When a patient presents with the classic constellation of TSS features, then MRI of the whole spine should be obtained.[12] Similarly, if initial imaging is at all inconsistent with the clinical picture established from history and examination, then a low threshold is required for further imaging of the entire spinal column.[15] Often, the patient will undergo MRI of the lumbar spine with the sagittal images terminating at the lower thoracic spine—these levels should be scrutinized and if there is any suspicion of stenosis as these levels further dedicated axial imaging obtained before any treatment recommendations are made.

Some authors, owing to the risk of missing tandem stenosis sometimes with catastrophic consequences when cord-level stenosis is not detected, have suggested that whole-spine MRI be considered in all patients undergoing surgical decompression of the lumbar spine to alert the clinician to stenosis elsewhere.[16] A simpler approach is to obtain scout T2 sagittal imaging on all patients being appraised for disease in one region, and further dedicated sequences can be obtained as needed (Figure 2). However, these approaches are, in reality, not always feasible in an era of increasing resource constraint. It is the authors' current practice to obtain dedicated imaging based on history and examination findings until such time that a "global imaging" approach is proven cost effective.

Figure 2.

Full-spine imaging allows a quick assessment for stenosis that may affect other noncontiguous spinal segments.

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