Lumbosacral Stenosis: Static or Dynamic Problem?

Introduction
Degenerative lumbosacral stenosis (DLSS) is a dynamic disease in many aspects. The controversies surrounding this disease syndrome are numerous and different views how to diagnose and treat DLSS make the discussion of this disease among veterinary colleagues a dynamic event!

Clinical signs
DLSS can present in a number of different ways and because of this patients suffering from DLSS can sometimes be misdiagnosed. DLSS patients are typically neuro-orthopedic patients, the disorder is per definition a spinal disease but the presentation is more that of an orthopedic disorder. As DLSS mainly affects middle-aged and older dogs they can often have other concurrent degenerative orthopedic or neurologic disorders such as, respectively, osteoarthritis or degenerative myelopathy. Hence it is helpful if these patients are subjected to both orthopedic and neurologic examinations.

Findings during orthopedic examination are directly related to the compression of the cauda equina, and the most consistent finding is lumbosacral pain on palpation. LS pain can be evoked by the lordosis test and hyperextension of the tail base with simultaneous pressure at the LS region. Hyperextension of the hip joints (one at a time) with the dog standing or in lateral recumbence should not cause pain unless the dog has pain derived from the hip. However, many dogs with DLLS and hip dysplasia allow gradual extension of the hip joints but start to show a pain reaction when hyperextending the lumbosacral junction. Especially in these cases the experienced clinician will note the difference between a mild response to extension of the dysplastic hip joint and the overt pain response due to added compression to the cauda equina. This is proof of the dynamic nature of the compression and stenosis which worsens in motions of extension (Fig. 1). Other common findings are uni- or bilateral hind limb lameness, atrophy of the hind limb musculature (innervated by the sciatic nerve) and a weight shift from hind limbs to the fore limbs. Unilateral entrapment of the L7 and/or S1 nerves (Fig. 1C) causes radiating nerve root pain (the so-called nerve root signature).  [...]