Evaluation of the Neuropathic Component of Chronic Low Back Pain.

OBJECTIVES: Assessment of neuropathic pain in chronic low back syndromes is important. However, there is currently no gold standard for its diagnosis. The aim of this observational cross-sectional study was to assess the neuropathic component of pain in various chronic low back pain syndromes using a range of diagnostic tests. MATERIALS AND METHODS: Included in this study were 63 patients with chronic axial low back pain (ALBP), 48 patients with chronic radicular syndromes (CRS) comprising 23 with discogenic compression (CDRS) and 25 with lumbar spinal stenosis (LSS), and 74 controls. PainDETECT questionnaire (PDQ), quantitative sensory testing (QST), and skin biopsy with evaluation of intraepidermal nerve fiber density (IENFD) were used to assess the neuropathic pain component. RESULTS: Positive PDQ (≥19) was obtained more frequently in patients with CDRS and LSS (26.1% and 12.0%, respectively) compared with patients with ALBP (1.6%, P<0.001). The proportion of patients with sensory loss confirmed by QST was lowest in the ALBP subgroup (23.8%) compared with CDRS (47.8%), and LSS (68.0%) subgroups (P<0.001). A reduction in IENFD was disclosed in a proportion of up to 52.0% of affected roots in patients with CRS. DISCUSSION: Neuropathic pain is quite frequent in CRS, and QST reveals sensory loss as a frequent abnormality in patients with CRS. Using a cut-off value of 19, PDQ identified a neuropathic component in a relatively low proportion of patients with CRS. CRS may be associated with a reduction in IENFD.

Does lumbar spinal stenosis increase the risk of spondylotic cervical spinal cord compression?

PURPOSE: The aim of this prospective cross-sectional observational comparative study was to determine the prevalence of spondylotic cervical cord compression (SCCC) and symptomatic cervical spondylotic myelopathy (CSM) in patients with symptomatic lumbar spinal stenosis (LSS) in comparison with a general population sample and to seek to identify predictors for the development of CSM. METHODS: A group of 78 patients with LSS (48 men, median age 66 years) was compared with a randomly selected age- and sex-matched group of 78 volunteers (38 men, median age 66 years). We evaluated magnetic resonance imaging findings from the cervical spine and neurological examination. RESULTS: The presence of SCCC was demonstrated in 84.6% of patients with LSS, but also in 57.7% of a sample of volunteers randomly recruited from the general population. Clinically symptomatic CSM was found in 16.7% of LSS patients in comparison with 1.3% of volunteers (p = 0.001). Multivariable logistic regression proposed the Oswestry Disability Index of 43% or more as the only independent predictor of symptomatic CSM in LSS patients (OR 9.41, p = 0.008). CONCLUSIONS: The presence of symptomatic LSS increases the risk of SCCC; the prevalence of SCCC is higher in patients with symptomatic LSS in comparison with the general population, with an evident predominance of more serious types of MRI-detected compression and a clinically symptomatic form (CSM). Symptomatic CSM is more likely in LSS patients with higher disability as assessed by the Oswestry Disability Index.

Small-nerve-fiber pathology in critical illness documented by serial skin biopsies.

INTRODUCTION: Small-fiber pathology can develop in the acute phase of critical illness and may explain chronic sensory impairment and pain in critical care survivors. METHODS: Eleven adult ischemic stroke patients in a neurocritical care unit were enrolled in an observational cohort study. Intraepidermal nerve fiber density (IENFD) in the distal leg was assessed on admission to the intensive care unit and 10-14 days later, together with electrophysiological testing. RESULTS: Of the 11 patients recruited, 9 (82%) had sepsis or multiple-organ failure. Median IENFD on admission (5.05 fibers/mm) decreased significantly to 2.18 fibers/mm (P < 0.001), and abnormal IENFD was found in 6 patients (54.5%). Electrodiagnostic signs of large-fiber neuropathy and/or myopathy were found in 6 patients (54.5%), and autonomic dysfunction was found in 2 patients (18.2%). CONCLUSION: Serial IENFD measurements confirmed the development of small-fiber sensory involvement in the acute phase of critical illness.

Alterations in the vascular architecture of the dorsal root ganglia in a rat neuropathic pain model.

An alteration in the structural arrangement of blood vessels identified by RECA immunohistochemistry was studied in a rat L4 dorsal root ganglia (L4-DRG) neuropathic pain model. We compared a three-dimensional (3-D) reconstruction of the vascular architecture surrounding bodies of the primary sensory neurons in the L4-DRG of naïve rats with that of rats that had surgically undergone unilateral sciatic nerve ligature. Rhodamine-conjugated dextran (Fluoro-Ruby) was used for retrograde labelling of neurons, the axons of which had been injured by nerve ligature. In contrast to DRG from naïve rats and contralateral DRG from operated rats, an increased proportion of RECA+ vascular area and the appearance of nest-like arrangements of blood vessels around neuronal bodies with injured axons were observed in L4-DRG ipsilateral to the sciatic nerve ligature. Fractal analysis confirmed a higher degree of vascular branching, irregularity, and tortuosity in L4-DRG related with sciatic nerve injury. The results suggest that nerve injury induces changes in vascular architecture in associated DRG.