Multimodal management strategies for chronic pain after spinal surgery: a comprehensive review

Characterizing a new rat model of chronic pain after spine surgery

Chronic pain after spine surgery (CPSS) is a complex disorder characterized by multifactorial pathogenesis that occurs in 8%-40% of patients undergoing lumbar spine surgery. We aimed to develop a rat model that mimics clinical CPSS conditions by taking two sequential surgical procedures. Step 1: A plastic rod was inserted into the left L5 intervertebral foramen to produce a steady compression on the dorsal root ganglion (DRG) and the spinal nerve, a common cause of low back pain (LBP). Step 2: The rod was removed after 7 days when rats exhibited mechanical and heat hypersensitivity in the ipsilateral hindpaw, followed by a full L5 laminectomy to mimic spine decompression surgery in LBP patients. The retention of the rod induced a prolonged LBP-like behavior but was quickly resolved after rod removal without laminectomy. However, rats that received laminectomy after rod removal developed heightened mechanical and heat sensitivity in the hindpaw, impaired gait, and reduced spontaneous exploration activity, indicating CPSS. Patch clamp recording revealed a significant augmentation in the intrinsic excitability of small-diameter DRG neurons in CPSS rats. Administration of Dermorphin [D-Arg2, Lys4] (1-4) amide (DALDA, 5 mg /kg, i.p.), a peripherally acting mu-opioid receptor (MOR)-preferred agonist, attenuated pain hypersensitivity, capsaicin-induced [Ca2+]i rising and the increased intrinsic excitability of DRG neurons from CPSS rats. Our findings suggest that this new model, which mirrors the nature of CPSS developed in patients, may be useful for future studies of the underlying mechanisms.

Catastrophizing as a Predictor for Pain Perception and Disability Among Patients Undergoing Spinal Cord Stimulation

Background and Objectives: The International Society for Modulation defines persistent spinal pain syndrome type 2 (PSPS-type 2), formerly known as failed back surgery syndrome, as a condition where patients continue to experience pain or develop new pain following spinal surgery intended to alleviate back or lower-limb discomfort. PSPS-type 2 is characterized by pain and significant disability, affecting quality of life. Spinal cord stimulation has proven effective in treating this syndrome, although the role of psychological factors, such as pain catastrophizing and central sensitization, remain unclear. This study seeks to examine the potential connection between psychosocial responses and both functionality and pain perception in patients with persistent spinal pain syndrome type 2 who have undergone spinal cord stimulation treatment. Materials and Methods: A single-site, cross-sectional study was conducted on individuals diagnosed with persistent spinal pain syndrome type 2 who were receiving spinal cord stimulation. Study participants were required to meet specific eligibility criteria and were assessed for disability, pain perception, fear of movement, pain catastrophizing, and central sensitization. The spinal cord stimulation procedure involved the placement of electrodes at vertebral levels T8-T11 for precise pain control, with a particular focus on targeting the dorsal root ganglion to alleviate chronic pain. Results: Thirty-seven patients with persistent spinal pain syndrome type 2 have undergone spinal cord stimulation treatment for 4.68 ± 5.25 years. Clinical assessments indicated a pain perception score of 5.6 ± 1.96, Central Sensitization Inventory score of 42.08 ± 18.39, disability score of 37.62 ± 16.13, fear of movement score of 33.11 ± 8.76, and pain catastrophizing score of 28.43 ± 13.14. Finally, pain catastrophizing was significantly associated with pain perception (β = 0.075 and p = 0.008) and disability (β = 0.90 and p < 0.01). Conclusions: Catastrophizing plays a crucial role in pain perception and disability among patients with persistent spinal pain syndrome type 2 receiving spinal cord stimulation. Integrating psychological interventions may improve clinical outcomes for these patients.

6. Persistent spinal pain syndrome type 2

INTRODUCTION

Persistent Spinal Pain Syndrome (PSPS) refers to chronic axial pain and/or extremity pain. Two subtypes have been defined: PSPS-type 1 is chronic pain without previous spinal surgery and PSPS-type 2 is chronic pain, persisting after spine surgery, and is formerly known as Failed Back Surgery Syndrome (FBSS) or post-laminectomy syndrome. The etiology of PSPS-type 2 can be gleaned using elements from the patient history, physical examination, and additional medical imaging. Origins of persistent pain following spinal surgery may be categorized into an inappropriate procedure (eg a lumbar fusion at an incorrect level or for sacroiliac joint [SIJ] pain); technical failure (eg operation at non-affected levels, retained disk fragment, pseudoarthrosis), biomechanical sequelae of surgery (eg adjacent segment disease or SIJ pain after a fusion to the sacrum, muscle wasting, spinal instability); and complications (eg battered root syndrome, excessive epidural fibrosis, and arachnoiditis), or undetermined.

METHODS

The literature on the diagnosis and treatment of PSPS-type 2 was retrieved and summarized.

RESULTS

There is low-quality evidence for the efficacy of conservative treatments including exercise, rehabilitation, manipulation, and behavioral therapy, and very limited evidence for the pharmacological treatment of PSPS-type 2. Interventional treatments such as pulsed radiofrequency (PRF) of the dorsal root ganglia, epidural adhesiolysis, and spinal endoscopy (epiduroscopy) might be beneficial in patients with PSPS-type 2. Spinal cord stimulation (SCS) has been shown to be an effective treatment for chronic, intractable neuropathic limb pain, and possibly well-selected candidates with axial pain.

CONCLUSIONS

The diagnosis of PSPS-type 2 is based on patient history, clinical examination, and medical imaging. Low-quality evidence exists for conservative interventions. Pulsed radiofrequency, adhesiolysis and SCS have a higher level of evidence with a high safety margin and should be considered as interventional treatment options when conservative treatment fails.