Carlo Cacciatori

Central sensitization in carpal tunnel syndrome with extraterritorial spread of sensory symptoms

&NA; Extraterritorial spread of sensory symptoms is frequent in carpal tunnel syndrome (CTS). Animal models suggest that this phenomenon may depend on central sensitization. We sought to obtain psychophysical evidence of sensitization in CTS with extraterritorial symptoms spread. We recruited 100 unilateral CTS patients. After selection to rule out concomitant upper‐limb causes of pain, 48 patients were included. The hand symptoms distribution was graded with a diagram into median and extramedian pattern. Patients were asked on proximal pain. Quantitative sensory testing (QST) was performed in the territory of injured median nerve and in extramedian territories to document signs of sensitization (hyperalgesia, allodynia, wind‐up). Extramedian pattern and proximal pain were found in 33.3% and 37.5% of patients, respectively. The QST profile associated with extramedian pattern includes: (1) thermal and mechanic hyperalgesia in the territory of the injured median nerve and in those of the uninjured ulnar and radial nerves and (2) enhanced wind‐up. No signs of sensitization were found in patients with the median distribution and those with proximal symptoms. Different mechanisms may underlie hand extramedian and proximal spread of symptoms, respectively. Extramedian spread of symptoms in the hand may be secondary to spinal sensitization but peripheral and supraspinal mechanisms may contribute. Proximal spread may represent referred pain. Central sensitization may be secondary to abnormal activity in the median nerve afferents or the consequence of a predisposing trait. Our data may explain the persistence of sensory symptoms after median nerve surgical release and the presence of non‐anatomical sensory patterns in neuropathic pain.

Pain and motor function in carpal tunnel syndrome: a clinical, neurophysiological and psychophysical study.

ObjectivePatients with carpal tunnel syndrome (CTS) complain of motor symptoms. The study is aimed to understand which features are associated with the presence of motor symptoms in CTS.MethodsWe recruited 282 consecutive CTS patients. After selection, 129 patients (203 hands) were included. Patients were asked about the presence and severity of hand weakness (HW) and hand clumsiness (HC). They underwent a self-administered questionnaire on symptoms, clinical evaluation and neurographic study. Quantitative sensory testing (QST) was performed on the patients with unilateral right CTS.ResultsHW and HC may be found in 56 % and 48 % of CTS hands, respectively. HW was related to the severity of sensory symptoms (pain, numbness and tingling) but not to clinical-neurographic measures of median nerve involvement. HC was related to the severity of sensory symptoms and to the clinical-neurographic signs of motor but not sensory nerve damage. Motor symptoms were significantly more frequent in right hands. QST showed a relationship between the presence and severity of HW and HC and the warm threshold.ConclusionsMotor symptoms may be found in approximately half of CTS hands. Clinical and neurographic signs of median nerve motor damage appear to be poorly correlated to motor symptoms. The factor that can help reconcile the discrepancy between motor symptoms and motor signs is pain. Pain modulation on motor function may take place at various anatomical levels in CTS. Nociceptive C-fibers may be involved in pain-motor interactions finally leading to motor symptoms.

Median Nerve Small- and Large-Fiber Damage in Carpal Tunnel Syndrome: A Quantitative Sensory Testing Study

UNLABELLED We explored the contribution of median nerve small (Aδ, C)-and large (Aβ)-fiber damage to the severity and topographic distribution of sensory symptoms in carpal tunnel syndrome (CTS) and the timing of fiber damage across CTS stages. We recruited 106 CTS patients. After selection, 49 patients were included. They underwent electrodiagnostic and quantitative sensory testing (QST) study and were asked on the severity of Boston Carpal Tunnel Questionnaire (BCTQ) Symptoms Severity Scale, daytime pain (DP), night pain and paresthesia, on the distribution of hand symptoms, and the presence of proximal symptoms. BCTQ Symptoms Severity Scale and DP severity was significantly correlated with Aδ-fiber damage. Small-fiber QST measures were impaired in electrodiagnostic-negative CTS patients and did not change across CTS neurographic stages. QST findings were not correlated to the topographical distribution of symptoms. Aδ-fiber damage contributes to CTS symptoms and in particular to DP. Night pain and paresthesia might be ascribed to ectopic fiber discharges secondary to median nerve enhanced mechanosensitivity. Small-fiber damage takes place earlier than large fiber. Median nerve fiber involvement does not directly contribute to extraterritorial symptoms spread. Our data may help understanding CTS pathophysiology and explain the well-known discrepancy between CTS symptoms and electrodiagnostic findings. PERSPECTIVE We explored the involvement of median nerve small and large fibers in carpal tunnel syndrome (CTS). We found a significant correlation between Aδ-fiber function and CTS symptoms. Small-fiber involvement took place in milder disease stages. These findings could help reconcile the discrepancy between CTS symptoms and electrodiagnostic data.

Ulnar nerve impairment at the wrist does not contribute to extramedian sensory symptoms in carpal tunnel syndrome

OBJECTIVE Extramedian spread of sensory symptoms is frequent in carpal tunnel syndrome (CTS) but its mechanisms are unclear. We explored the possible role of subtle ulnar nerve abnormalities in the pathogenesis of extramedian symptoms. METHODS We recruited 350 CTS patients. After selection, 143 patients (225 hands) were included. The hand symptoms distribution was graded with a diagram into median (MED) and extramedian (EXTRAMED) pattern. We tested the correlation of ulnar nerve conduction measures with the distribution and the severity of symptoms involving the ulnar territory. The clinical significance of ulnar nerve conduction findings was explored with quantitative sensory testing (QST). RESULTS EXTRAMED distribution was found in 38.7% of hands. The ulnar neurographic measures were within normal values. Ulnar nerve sensory measures were significantly better in EXTRAMED vs MED hands and not significantly correlated to ulnar symptoms severity. Ulnar and median nerve sensory measures were significantly correlated. QST showed normal function of ulnar nerve alphabeta-fibers. CONCLUSIONS Ulnar nerve sensory abnormalities do not contribute to the spread of sensory symptoms into the ulnar territory. SIGNIFICANCE Our data favour the hypothesis that spinal and supraspinal neuroplastic changes may underlie extramedian spread of symptoms in CTS.

Brachial artery blood flow during submaximal isometric contraction of the biceps brachii and triceps brachii in humans: A preliminary observation

The purpose of this study was to evaluate brachial artery blood flow changes during submaximal isometric contraction of the biceps and triceps brachii, in order to clarify the influence of the upper arm muscles activity on the local arterial flow. The brachial artery blood flow velocity and diameter were evaluated in twenty healthy men (mean age 29.6 years) at baseline (resting position) and during submaximal isometric contraction of the biceps and triceps brachii by means of ultrasonography (B-MODE and Doppler ultrasound methods). The brachial artery blood flow velocity was significantly higher than resting position during submaximal isometric contraction of the biceps (P < 0.001) and triceps brachii (P = 0.019). As to the brachial artery diameter, no significant change was observed during submaximal isometric contractions of the biceps and triceps brachii. Our preliminary findings suggest that the brachial artery blood flow velocity similarly increases during submaximal isometric contraction of the biceps and triceps brachii.

132 ULNAR NERVE IMPAIRMENT AT THE WRIST IS NOT CORRELATED WITH EXTRAMEDIAN SPREAD OF SENSORY SYMPTOMS IN CARPAL TUNNEL SYNDROME

Background & Aims: Pain is the most prominent but least well-studied feature of osteoarthritis (OA). Retrograde labelling of neurons innervating the OA joint decreases 40% at 31 days of disease progression, with the total number of DRG cells remaining unaltered, but increasing the number of medium-large cells. Therefore, we hypothesized that neuronal damage might be occurring during OA, and to test this hypothesis we evaluated the expression of ATF-3 and NPY (known to be increased by neuronal damage) in DRG neurons. Since ATF-3 has also been associated with the regeneration of injured cells, we also evaluated its colocalization with the regeneration marker GAP-43. Methods: All procedures were performed according to the ethical guidelines for the study of experimental pain in conscious animals. OA was induced by injection of 2mg of mono-iodoacetate in the knee joint of adult Wistar rats. Animals were sacrificed at 3, 7 and 14 days post-injection. L3-L5 DRGs were used for immunohistochemistry for NPY, ATF-3 and GAP-43. Results: An increase in the number of ATF-3-positive cells was observed 3 days after the induction of OA. Such increase diminished over time, but the percentage of ATF-3 cells positive for GAP43 increased at days 7 and 14. NPY expression showed a similar pattern as ATF-3 expression. Conclusion: The increased ATF-3 and NPY expression suggests that damage in DRG neurons innervating the OA joint may be occurring. The increased co-localization of ATF-3 and GAP-43 over time indicates that neuronal regeneration may be taking place as a response to neuronal damage.

178 INTRAVENOUS IMMUNOGLOBULINS TREATMENT IMPROVES PAIN IN DIABETIC LUMBOSACRAL RADICULOPLEXUS NEUROPATHY

number of subjects on treatment for at least 6 or 12 months was 182 and 91, respectively. Marked reductions in the Likert pain score on average among the patients were observed over the whole treatment period. Eighteen (18, 8%) subjects discontinued the trial for adverse events. The most common AEs included dizziness, vertigo, headache, nasopharyngitis, fatigue, and nausea. The poster will present updated and more detailed results from an upcoming analysis.