90 Neurogenic versus Vascular Claudications

Case 90 Neurogenic versus Vascular Claudications

Eric P. Roger and Edward Benzel

Fig. 90.1 (A) Axial T2- weighted magnetic resonance image (MRI) at the L4–L5 disk space. (B) Sagittal T2- weighted MRI of the lumbar spine at the level of the midline.

Clinical Presentation

A 69-year-old man presents with difficulty ambulating.

The patient also complains of leg “tightness” when he stands or walks, which completely resolves with sitting or leaning over a countertop.

He has no back pain and no bladder or bowel dysfunction.

A magnetic resonance imaging (MRI) scan is obtained and shown in Fig. 90.1.

Questions

Interpret the MRI.
What other radiologic imaging would you order?
What is the differential diagnosis of his leg symptoms?
What elements in the clinical presentation would help differentiate spinal versus vascular type of claudication?
What other diagnostic modality would help differentiate the two?

The patient has no evidence of arterial insufficiency on examination and has a positive “shopping cart” sign (resolution of the leg pain when leaning on a shopping cart while walking). He is able to use a stationary bicycle without pain or symptoms. His ankle brachial indices (ABIs) are 1.10 on the right, 1.08 on the left side.
What therapeutic options are available to this patient?
What is the likelihood of destabilizing the spondylolisthesis with a simple decompressive laminectomy? What are some risk factors of this procedure?
Should a fusion be added to his surgical treatment? Should instrumentation also be added?

Answers

Interpret the MRI.

The images demonstrate a grade 1 spondylolisthesis of L4 over L5.
There is no element of pars defect, at least on these images.
There is resulting severe central stenosis at that level, and to a lesser extent at the level above (L3–L4).
Paracentral cuts would be required to fully assess the amount of foraminal stenosis present.

What other radiologic imaging would you order?

Plain radiographs would be essential in the evaluation of this patient. Standing anteroposterior, lateral, and oblique views should be obtained.
In addition, dynamic films (flexion and extension views) would be useful.
MRI may underestimate the degree of listhesis as the images are performed in the supine position. Standing radiographs may show an accentuation of the L4–L5 slip, therefore suggesting instability.
This may be confirmed by flexion/extension (flex/xt) views.
Oblique views may be useful to assess a pars defect, with a lysis seen across the neck of the “Scotty dog” appearance of the vertebrae.
Computed tomography scan of the lumbar spine can also be used to assess the pars integrity

What is the differential diagnosis of his leg symptoms?

Although the differential diagnosis of leg “tightening” and similar symptoms can be attributed to a vast array of etiologies, including neurodegenerative disorders, hip and/or knee pathology, metabolic causes, etc., the two most likely diagnoses are neurogenic and vascular claudications.1
What elements of the clinical presentation would help differentiate spinal versus vascular type of claudication?
- Vascular claudications¹
  - Symptoms
    - Calf pain with walking (classic)
    - Buttock, thigh, and/or foot pain may also be present
    - Brought on by walking or other activity
    - Relieved within a few minutes of rest
    - Numbness and/or weakness may be present
    - Rest pain in advanced cases
  - Signs
    - Decreased pulses and bruits
    - Skin changes of arterial insufficiency (shiny, glistening, atrophic, ulcerated, loss of hair, nail changes)
    - Pallor when elevated
    - Dusky rubor when placed in a dependent state (Buerger’s sign)
- Neurogenic claudication¹
  - Symptoms
    - Leg pain with standing or walking
    - May be described as weakness or “giving out”
    - Often associated with numbness, potentially dermatomal if stenosis is foraminal
    - Brought on by walking and/or standing
    - Relieved relatively quickly with sitting or bending forward
  - Signs
    - Often normal on examination
    - May have diminished deep tendon reflexes
    - May have dermatomal paresthesias
    - May have positive straight leg raising (Lasègue sign)
    - Wide-based gait
- Differentiation of neurogenic versus vascular claudications^1,2
  - Symptoms
    - Neurogenic aggravated by standing or walking; vascular aggravated by walking but not just standing.
    - Neurogenic improves faster after sitting than does vascular.
    - Neurogenic improves by walking bent forward, as for example with the use of a shopping cart (“shopping cart sign”).
    - Vascular aggravated by use of stationary bicycle; not neurogenic
  - Signs
    - Vascular claudication patients “look vasculopathic,” with skin changes, nail changes, hair loss. Diminished pulses may be noted.
    - Neurogenic claudication patients often have a relatively normal examination, although neural deficits may be noted.
What other diagnostic modality would help differentiate the two?
- ABI: ratio of Doppler-measured blood flow in upper versus lower extremities
  - Normal ratio is >1.
  - A ratio of 0.6–0.9 indicates the claudicant range.
  - A ratio ≤0.5 correlates with rest pain and ulceration.
What therapeutic options are available to this patient?
- Conservative management³
  - Medications (unlikely to be beneficial): include nonsteroidal antiinflammatories, gabapentin or other antiepileptics use to treat neuropathic pain, other pain medications.
  - Therapies^4–6
    - Physical therapy
    - Pilates therapy
    - Exercise therapy
    - Chiropractic therapy
    - Traction
  - Injections⁶
    - Epidural
    - Selective nerve root blocks
- Surgical management3,7
  - Decompression (open or minimally invasive)^8–10
    - Laminectomies¹¹
    - Laminotomies and foraminotomies¹²
    - Laminoplasty
    - Interspinous decompression via a spinous process spacer device¹³
  - Decompression and fusion¹⁴
- Noninstrumented
  - Facet fusion
  - Posterolateral onlay fusion
- Instrumented^15,16
  - Posterolateral fusion (PLF)
  - Posterior lumbar interbody fusion¹⁵
  - Transforaminal lumbar interbody fusion (TLIF)
  - Anterior lumbar interbody fusion (indirect decompression) not generally recommended in these cases
What is the likelihood of destabilizing the spondylolisthesis with a simple decompressive laminectomy? What are some risk factors of this procedure?
- The likelihood of destabilizing a low-grade (I or II) spondylolisthesis after laminectomy is poorly reported in the literature.
- There are certain factors that may predispose to an increased risk of destabilization.²
  - Preoperative:
    - Pars defect (isthmic)
    - Evidence of instability on flexion/extension films: >4.5 mm of translation¹⁷
    - Presence of a tall disk space
    - Sagittally oriented facets
    - Overweight patient
  - Intraoperatively
    - Partial or generous facetectomy
    - Injury to the pars interarticularis
    - Overt evidence of instability
Should a fusion be added to his surgical treatment? Should instrumentation also be added?
- Although the rate of spondylolisthesis progression after simple decompression is unclear, several studies have reported improved clinical outcomes after fusion (with or without instrumentation).
- The Lumbar Fusion Guidelines¹⁸ have therefore stated the following:
  - “Guidelines: The performance of a lumbar PLF is recommended for patients with lumbar stenosis and associated degenerative spondylolisthesis who require decompression. There is insufficient evidence to recommend a treatment guideline.”¹⁸
- It would appear that the addition of instrumentation to the fusion procedure increases the radiologic rate of fusion, although most studies have shown no statistical improvement in clinical outcome.
- In this regard, the Lumbar Fusion Guidelines¹⁸ have stated the following:
  - “Options. Pedicle screw fixation as an adjunct to lumbar PLF should be considered as a treatment option in patients with lumbar stenosis and spondylolisthesis in cases in which there is preoperative evidence of spinal instability or kyphosis at the level of the spondylolisthesis or when iatrogenic instability is anticipated.”¹⁸
- A prospective randomized control trial, the Spinal Laminectomy Versus Instrumented Pedicle Screw Fusion Study, is currently under way to compare decompression versus decompression and instrumented fusion in patients with stenotic grade I spondylolisthesis.^19,20