Diagnosing and assessing pain in neurorehabilitation: from translational research to the clinical setting. Evidence and recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation.

Pain is very common in neurorehabilitation, where it may be a target for treatment and have a negative effect on rehabilitation procedures and outcomes. Promising preliminary preclinical data support certain therapeutic approaches to pain, but there is a strong need of adequate preclinical models, experimental settings, outcome measures, and biomarkers that are more relevant for pain within the neurorehabilitation field. Data on the diagnosis and assessment of nociceptive and neuropathic pain (NP) are very scanty in neurorehabilitation, but those from other contexts can be adapted and translated to this specific setting. The Italian Consensus Conference on Pain in Neurorehabilitation (ICCPN) has searched and evaluated existing evidence on animal models for the treatment of pain, definition and diagnostic criteria for nociceptive and NP, screening tools and questionnaires, along with diagnostic, clinical and instrumental techniques to distinguish nociceptive from NP and, more generally, to assess pain in the field of neurorehabilitation. The present ICCPN recommendations provide information on the relevance of current preclinical models, and may be helpful in ameliorating pain diagnosis and assessment, which are prerequisites for better application and tailoring of current pharmacological and non-pharmacological treatments. They may also be useful for future studies aimed at filling the gaps in the current knowledge of these topics.

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.

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 (Aß)-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.

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

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.

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.