Comparing clinical outcomes of dogs suffering from degenerative lumbosacral stenosis upon surgical or nonsurgical treatment
Goh Rui Qi, K.
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PICO question
In dogs suffering from degenerative lumbosacral stenosis (DLSS), is surgical treatment more effective than nonsurgical therapy in reducing lumbosacral pain and neurological dysfunction in the long-term?
Clinical bottom line
Category of research
Treatment.
Number and type of study designs reviewed
Two papers were critically reviewed. They were prospective and retrospective studies.
Strength of evidence
Weak.
Outcomes reported
Besides the two studies, there are no other studies currently available that directly compare long-term clinical outcome of patients that have undergone nonsurgical and surgical treatment respectively.
In the study comparing clinical outcome of nonsurgical treatment by epidural steroid injection (ESI) and surgical treatment of degenerative lumbosacral stenosis, dogs were classified into clinical severity groups ranging from mild to moderate to severe. Mild cases demonstrated degenerative lumbosacral stenosis (DLSS) compatible clinical signs such as lumbosacral pain, reluctance to climb stairs / jump / raise up, lameness and muscle atrophy but no neurological deficits. Moderate cases presented DLSS compatible clinical signs in combination with neurological deficits such as reduced flexor withdrawal, proprioceptive deficits and nerve root signature. Severe cases demonstrated DLSS compatible clinical signs with more severe neurological deficits such as tail paresis and absent perineal reflex. Clinical outcomes were considered complete if clinical signs had resolved at follow-up consultations, partial if there was substantial but incomplete improvement in clinical signs and failed if the dog did not improve or deteriorated further. Improvements in patient condition were measured in terms of clinical outcome grading which is in relation to the initial clinical severity group assigned to each dog. Improvement after single dose of ESI was seen in 27/32 dogs, with 17/22 (after accounting for four dogs whose owners have refused further treatment, five dogs lost to follow-up after re-check as well as one dog whose owners have opted for repeated ESI instillations) relapsing within 6 months. All 17 of these dogs that suffered a relapse after single ESI subsequently underwent surgical treatment and demonstrated improvement in clinical signs, with a complete response seen in eight dogs and a partial response seen in nine dogs.
In the study comparing clinical outcome of conservative treatment of exercise restriction with phenylbutazone administration and surgical treatment of degenerative lumbosacral stenosis, outcomes were classified as good in dogs that regained preoperative activity levels; acceptable in dogs with persistent abnormality or requiring continued medication though otherwise active, and poor in all other cases. Out of 16 dogs treated surgically, 11 were treated by dorsal lumbosacral laminectomy and excision of the dorsal portion of the lumbosacral disc, while the other five had additional unilateral facetectomy to decompress the seventh lumbar nerve. Out of the 11 dogs treated with dorsal lumbosacral laminectomy and excision of the dorsal portion of the lumbosacral disc, 6/11 (54.5%) of dogs were deemed to have a good outcome, while 3/11 (27.3%) of dogs were deemed to have an acceptable outcome. Out of the five dogs treated with dorsal lumbosacral laminectomy and excision of the dorsal portion of the lumbosacral disc with additional unilateral facetectomy, 3/5 (60%) of dogs were deemed to have an acceptable outcome. The outcome of conservative treatment was deemed good in 8/16 (50%) of dogs in the conservative treatment group.
Conclusion
There is evidence suggesting that both nonsurgical and surgical treatments can improve clinical outcomes and reduce lower back pain and neurological deficits. However, based on the current limited literature, it cannot be ascertained whether surgical treatments are more effective than nonsurgical treatments in improving long-term clinical outcomes and vice versa. In the study that tested the efficacy of epidural steroid injection, only a single dose of steroids was given in this study, making it a potential reason for the high rate of relapse following nonsurgical treatment. For surgical treatment of DLSS, the type of surgical procedure chosen would also depend on the part of the lumbosacral region which fails and leads to compression. In conclusion, randomised controlled trials that compare different forms of nonsurgical treatment with surgical treatment for dogs with DLSS caused by different underlying factors need to be conducted to properly address the PICO question.
How to apply this evidence in practice
The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.
Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.
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Appraisal, application and reflection
Canine degenerative lumbosacral stenosis (DLSS) represents a syndrome in dogs that comprises of lumbosacral pain as well as neurological dysfunction in some cases. This syndrome is related to the degeneration and subsequent enlargement of the soft tissue structures of the lumbosacral junction as well as compression of the cauda equina (Worth et al., 2019). It is a common disorder which is multifactorial in origin, with intervertebral disc degeneration (IVD) being a major contributor (Meij & Bergknut, 2010). In particular, intervertebral disc protrusion caused by fibroid metaplasia as well as the development of small separations in the lamellae of the annulus fibrosus has been identified as a contributing factor to DLSS. The process of fibroid metaplasia refers to the increased collagen content and change in the notochordal cells to become more fibrocyte-like, coupled with the decreased integrity of the lamellae of the annulus fibrosus. This leads to extension of degenerative fibroid nuclear material into and between the fibres of the annulus. Eventually, the surface of the annulus fibrosus gradually thickens and protrudes, displacing the dorsal longitudinal ligament and gradually compressing the nerve roots (Fenn et al., 2020).
Possible causes of lumbosacral disease include cauda equina compression which can occur from lateral disc protrusion which compresses the sciatic nerve at the foramen level. Other causes also include synovial cysts as well as dynamic compression in lumbosacral dorsi-flexion but otherwise minimal compression in neutral position. Compression could be categorised as dynamic when instability and thus motion of the vertebral segments results in variation in severity of compression from moment to moment depending on the position of the vertebrae at a specific point in time (Jeffery et al., 2013). The spinal nerves originating from the lumbosacral section of the vertebral column stretches to the hips, stifle, tarsus, urinary bladder as well as anal and urinary sphincters, in order from L4 to S3. Neurological findings associated with degeneration at L4-S1 often presents as femoral pseudo-hyperreflexia, muscle atrophy and potentially decreased reflexes due to impingement of the femoral and sciatic nerves.
The proposed pathogenesis for canine DLSS involves disc degeneration resulting in ventral subluxation of the sacrum as well as thickening of the articular processes, which results in structural failure of the disc (Meij & Bergknut, 2010). In response to the proposed disease pathogenesis, current surgical treatments such as dorsal laminectomies are conducted to relieve pressure on the cauda equina and foraminotomies are performed with the aim of decompressing the sciatic nerve and releasing nerve roots which are entrapped. The type of surgery indicated would depend on the direction of protrusion, with dorsal laminectomies being indicated for dorsal ventral disc protrusion and foraminotomies being indicated for foraminal protrusions. Presence of ventral subluxation of S1, which refers to the S1 disc being more ventrally displaced as compared to neighbouring vertebrae, as well as dynamic compression, often indicates the need for fixation and fusion stabilisation to reduce the abnormal mobility of the vertebrae which was identified as instability.
It has been speculated that cell-mediated inflammatory responses occur upon disc damage, which results in ingrowth of blood vessels and nerves into the damaged disc, exacerbating lumbosacral pain. Nonsurgical treatments for DLSS work to mediate the inflammatory responses that occur during disc damage, often using nonsteroidal anti-inflammatory drugs (NSAIDs), a change in exercise pattern as well as reduction in body weight. In more recent times, lumbosacral epidural injections of corticosteroids have been reported to be effective in improving symptoms for dogs with DLSS.
Only two studies out of the many focusing on treatment of DLSS compared the efficacy of nonsurgical treatment compared to surgical treatment. In the first study, Gomes et al. (2020) evaluated the efficacy of epidural steroid injection (ESI) of methylprednisolone acetate. Out of 32 dogs that received the ESI, only five experienced persistent improvement without relapse, while 17 dogs ultimately underwent decompressive surgery. In this study, epidural steroid injection appears to only be successful in the long-term in a small number of dogs. In the second study, Ness (1994) evaluated the clinical outcomes of 16 dogs being treated surgically against 16 dogs treated under conservative treatment. In this study, surgical treatment was successful in alleviating pain in 13/16 81.3% of dogs, while conservative treatment was considered good in 8/16 (50%) of dogs. While this study attempted to compare clinical outcomes of surgically and conservatively treated dogs with DLSS, the outcome measures are not standardised, and it was not mentioned clearly what ‘good’ referred to in the dogs being conservatively treated. It is to be noted that the author conducted a facetectomy in five surgically treated cases, a technique which carries risks of exacerbating existing instabilities (Bebchuk, 2017).
With regards to papers published focusing on the clinical outcomes of dogs treated using surgical treatment only, Hankin et al. (2012) evaluated dogs with DLSS that had undergone transarticular facet screw stabilisation and dorsal laminectomy for long-term outcome through a retrospective study. Follow-up radiographs of the surgical site showed evidence of bone healing and stabilisation of the distracted lumbosacral intervertebral disc (IVD) space in all 15 dogs available for long-term follow-up. 11/13 (84.6%) owner questionnaires returned also demonstrated that the dog had regained normal ability to run and jump without perceptible lameness, signaling that the surgical procedure was highly successful. Gomes et al. (2018) evaluated the long-term outcome of dogs with DLSS that have undergone lateral foraminotomy through a retrospective study and 33/34 (97.1%) of the cases showed a long-term complete resolution of clinical signs. Golini et al. (2012) performed a retrospective study on dogs with DLSS which had undergone dorsal laminectomy and transarticular fixation of the facet joints using screws instead of pins. Clinical outcome improved in 13/17 (76.5%) dogs. As compared to a study conducted by Hankin et al. (2012) which involved the same surgical procedure with a success rate of 23/26 (88.5%) in terms of improvement in clinical outcome, success rate appears to be lower at 13/17 (76.5%). Despite the slight differences in success rates, transarticular facet screw stabilisation and dorsal laminectomy appears to be mostly effective in improving clinical outcome long-term in dogs with DLSS. Danielsson & Sjöström (1999) monitored the long-term outcome of dogs with DLSS that had undergone dorsal laminectomy and dorsal fenestration, with 122/131 (93.1%) of the dogs showing improvement clinically within the follow-up period.
With regards to papers published focusing on the clinical outcomes of dogs treated using nonsurgical treatment only, De Decker et al. (2014) evaluated the difference in clinical outcome for dogs treated nonsurgically through restricted exercise in combination with anti-inflammatory and analgesic drugs for DLSS. It was found that 17/21 dogs on medical management had obvious improvement or resolution of clinical signs, which makes up 81%. Based on this study, it appears that conservative treatment has reasonable success in resolving lower back pain and neurological deficits in the long-term. In a case report by Mrkovaĉki et al. (2021), a dog diagnosed with DLSS was injected with cultured autologous adipose tissue-derived mesenchymal stem cells (AT-MSCs) bilaterally at the level of L7-S1. Clinical outcome 60 days post AT-MSC treatment was positive, with absence of pain upon L7-S1 region palpation and negative lordosis test. Movement was also normal without stiffness of the hindlimbs, with preservation of all neurologic reflexes. However, due to the small sample size (n = 1), there is a need for further studies to be conducted on this treatment method to gather more meaningful data for widespread clinical use.
In conclusion, while it appears that surgical treatment does resolve lumbosacral pain and neurological dysfunction in the long-term in a proportion of dogs with DLSS, it is important to note that there is a serious lack of studies conducted on dogs diagnosed with DLSS who have undergone nonsurgical treatment, although this is a very common form of treatment in dogs diagnosed with DLSS today. It is generally understood that dogs with severe DLSS tend to have higher rates of improvement with surgical treatment, though a standardised grading system for DLSS according to clinical signs as well as pathogenesis would be helpful in streamlining dogs for further studies. Investigations into how the underlying pathogenesis of DLSS correlates with the success rate in surgical and / or nonsurgical treatment would greatly benefit from a DLSS grading system. For surgical treatments, it is pertinent for the specific part of lumbosacral failure to be identified in dogs admitted to the sample population so that future evaluation of the efficacy of surgical treatments can be more targeted and allow for more informed decision-making in clinical practice. There should also be the establishment of a standardised pet owner questionnaire to be used across all DLSS studies regarding the post-treatment condition of their dog. With these tools made available, more randomised control studies then need to be carried out.
While considering the best type of treatment for long-term resolution of DLSS, it is crucial to appreciate that lumbosacral disease waxes and wanes. In the case of severe uncontrollable pain, surgery is indicated with the purpose of controlling the pain using the shortest time possible, though it does sometimes resolve the signs of lumbosacral disease in the long-term. Due to the current lack of reliable and strong evidence for the long-term outcome for dogs with DLSS that had undergone surgical and nonsurgical treatment of DLSS respectively, it cannot be confidently ascertained that surgical treatment is more effective than nonsurgical treatment in reducing lower back pain and neurological dysfunction in the long-term.
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