Spinal Cord Injury Pain Instrument and painDETECT questionnaire: Convergent construct validity in individuals with Spinal Cord Injury.

BACKGROUND: Neuropathic pain (NeuP) is a frequent sequel of spinal cord injury (SCI). The SCI Pain Instrument (SCIPI) was developed as a SCI-specific NeuP screening tool. A preliminary validation reported encouraging results requiring further evaluation in terms of psychometric properties. The painDETECT questionnaire (PDQ), a commonly applied NeuP assessment tool, was primarily validated in German, but not specifically developed for SCI and not yet validated according to current diagnostic guidelines. We aimed to provide convergent construct validity and to identify the optimal item combination for the SCIPI. The PDQ was re-evaluated according to current guidelines with respect to SCI-related NeuP. METHODS: Prospective monocentric study. Subjects received a neurological examination according to the International Standards for Neurological Classification of SCI. After linguistic validation of the SCIPI, the IASP-grading system served as reference to diagnose NeuP, accompanied by the PDQ after its re-evaluation as binary classifier. Statistics were evaluated through ROC-analysis, with the area under the ROC curve (AUROC) as optimality criterion. The SCIPI was refined by systematic item permutation. RESULTS: Eighty-eight individuals were assessed with the German SCIPI. Of 127 possible combinations, a 4-item-SCIPI (cut-off-score = 1.5/sensitivity = 0.864/specificity = 0.839) was identified as most reasonable. The SCIPI showed a strong correlation (rsp  = 0.76) with PDQ. ROC-analysis of SCIPI/PDQ (AUROC = 0.877) revealed comparable results to SCIPI/IASP (AUROC = 0.916). ROC-analysis of PDQ/IASP delivered a score threshold of 10.5 (sensitivity = 0.727/specificity = 0.903). CONCLUSION: The SCIPI is a valid easy-to-apply NeuP screening tool in SCI. The PDQ is recommended as complementary NeuP assessment tool in SCI, e.g. to monitor pain severity and/or its time-dependent course. SIGNIFICANCE: In SCI-related pain, both SCIPI and PainDETECT show strong convergent construct validity versus the current IASP-grading system. SCIPI is now optimized from a 7-item to an easy-to-apply 4-item screening tool in German and English. We provided evidence that the scope for PainDETECT can be expanded to individuals with SCI.

Does measuring the median nerve at the carpal tunnel outlet improve ultrasound CTS diagnosis?

INTRODUCTION: Nerve conduction is often regarded as more sensitive than ultrasonography (US) for diagnosing carpal tunnel syndrome (CTS). The diagnostic value of US derives from median nerve enlargement occurring at both ends of the carpal tunnel resulting in a dumbbell-like swelling from carpal tunnel pressure. An important reason for the inferior sensitivity of US may be because measurements are restricted to the carpal tunnel inlet. We investigate the value of including median nerve enlargement at the carpal tunnel outlet for diagnosing CTS. METHODS: Retrospective cohort study of nerve conduction verified CTS, determining sensitivity, specificity, and positive and negative predictive values of carpal tunnel inlet and outlet median nerve cross sectional area as determined by US for the diagnosis of CTS. Nerve conduction graded CTS severity. RESULTS: 127 hands from 77 patients with CTS and 35 control healthy hands were assessed. US sensitivity for diagnosing CTS increased from 65% to 84% by including outlet enlargement of the median nerve. Specificity changed from 94% to 86%, positive predictive value from 98% to 96% and the negative predictive value from 43% to 60%. 25 hands out of the 127 from CTS patients showed enlargement restricted to the outlet and mainly occurred in moderate CTS. CONCLUSION: In our population, the use of carpal tunnel outlet median nerve enlargement in addition to inlet median nerve size increases sensitivity for diagnosing CTS by 19%.

Aquagenic wrinkling of the palms is due to vasoconstriction of palmar skin vasculature.

Aquagenic wrinkling of the palms is an unusual and rare dermatosis characterized by rapidly appearing edema, whitish papules, and strong wrinkling of the palms after brief immersion in water. Aquagenic wrinkling of the palms is postulated to be a result of abnormal electrolyte fluxes that result in sodium retention within epidermal keratinocytes and osmotically induced cell volume increases. A clear understanding is lacking. It is closely linked to Cystic Fibrosis and has been proposed as a test of Cystic Fibrosis but can also be induced by Cyclooxygenase (COX-2) inhibitors and Aminoglycosides. Since both aquagenic wrinkling of the palms and water immersion wrinkling occur with water immersion, are restricted to the glabrous skin, and show features of sympathetic stimulation, I hypothesize that aquagenic wrinkling of the palms is part of the spectrum of water immersion wrinkling which has recently been shown to be due to sympathetic nervous system induced vasoconstriction of the palms and digits. Furthermore I hypothesize that both conditions are restricted to the glabrous palmar skin because of unique anatomical characteristics. Palmar skin is highly porous to water and contains abundant specialized vasculature densely innervated by sympathetic nerves and has unique epidermal anchoring for gripping purposes. I postulate that in conditions with sweat electrolyte disturbances such as Cystic Fibrosis or drug induced; the normal water immersion wrinkling response is exaggerated, leading to the typical clinical features of aquagenic wrinkling of the palms.

Combined Doppler and B-mode sonography in carpal tunnel syndrome.

An intraoperatively enlarged engorged median nerve has been described as typical of patients with carpal tunnel syndrome (CTS). Although many studies of CTS have addressed median nerve enlargement, little is known about the usefulness of Doppler methods in detecting median nerve engorgement combined with nerve cross-sectional area (CSA). In a retrospective study of hands referred for evaluation of possible CTS, patients were clinically graded into Highly-likely or Indeterminate CTS. Nerve conduction studies (NCS), CSA, and Doppler analysis were compared. Median nerve blood flow was detected in 29 of 30 Highly-likely CTS hands (mean 13.3m/s (8.2) SD) and in 25 of 30 with Indeterminate CTS (mean 8.5m/s (4.5) SD). These were significantly higher than our laboratory normal values (mean 1.9 m/s (2.8) SD). Raised intraneural blood flow showed the highest test sensitivity in diagnosing Highly-likely carpal tunnel syndrome (83%) and combined with CSA reached 90%. NCS sensitivity was 83%. In the group of Indeterminate CTS, combined blood flow and CSA showed abnormality in 77% and NCS 47%. All nerve conduction parameters and median nerve cross sectional area showed linear correlation to intraneural blood flow velocity (P<0.05; Spearman's r=0.362 to 0.264). This study suggests that adding measures of intraneural blood flow to CSA further improves the sonographic evaluation of CTS and may be of particular use in patients with negative NCS.

Sonography versus nerve conduction studies in patients referred with a clinical diagnosis of carpal tunnel syndrome.

PURPOSE: To compare the diagnostic value of high-resolution ultrasound (US) with nerve conduction studies (NCS) in patients with clinically defined carpal tunnel syndrome (CTS). METHODS: A prospective study was conducted on 66 consecutive patients investigated for sensory hand symptoms. The gold standard was the clinical diagnosis of CTS. RESULTS: NCS showed greater diagnostic sensitivity (82%) than US (62%) in supporting a diagnosis of CTS. With increasing neurophysiologic severity of median neuropathy, there was increasing convergence of the two test methods. Abnormal US as the only diagnostic supportive evidence of CTS was rare. However, the positive predictive value of US for CTS was 100%. CONCLUSION: NCS show better sensitivity than US in supporting a diagnosis of CTS. However, because of its high positive predictive value, one may consider using US as a screening test, eliminating the need for NCS in the majority of clinical suspicion of CTS and reserving NCS for cases in which US is negative.

Sonography as an aid to neurophysiological studies in diagnosing tarsal tunnel syndrome.

Diagnosing tarsal tunnel syndrome can be difficult because of varying clinical diagnostic criteria and equivocal physical signs. We present a case of tarsal tunnel syndrome where nerve conduction identified distal tibial neuropathy and high-resolution sonography was able to show nerve swelling within the tarsal tunnel.

Sensory distribution indicates severity of median nerve damage in carpal tunnel syndrome.

OBJECTIVE: Sensory symptoms within the median nerve distribution are a primary clinical diagnostic criterion for the diagnosis of carpal tunnel syndrome (CTS). However, the distribution of the sensory symptoms in CTS varies from patient to patient. This study identifies the clinical and electrophysiological findings that correlate with the distribution of sensory symptoms in an Asian population with CTS. METHODS: In a prospective study of 105 patients with electrophysiologically confirmed CTS, clinical and educational data were correlated with sensory symptom distribution. RESULTS: Median nerve distribution was strongly associated with more severe nerve conduction abnormality, male gender, and relief by movement. Patients with a complete median sensory distribution had more electrophysiological abnormality than those with an incomplete median distribution. Extra-median distribution was associated with the least nerve conduction abnormality. Educational qualification, age, symptom duration and body mass index were not associated with the pattern of sensory symptoms. CONCLUSIONS: In carpal tunnel syndrome, sensory symptom distribution is strongly dependant on the degree of electrophysiological median nerve damage. Median nerve sensory distribution is associated with severe nerve damage. SIGNIFICANCE: This study provides clinicians with a simple clinical rule for assigning the degree of median nerve damage in patients with CTS based on sensory distribution patterns.

Skin wrinkling for diagnosing small fibre neuropathy: comparison with epidermal nerve density and sympathetic skin response.

OBJECTIVE: To compare simple tests of small nerve fibre function with intraepidermal nerve fibre density (IENFD) in the evaluation of small fibre neuropathy (SFN). METHODS: Patients with idiopathic SFN of the hands were prospectively studied. Evaluation involved clinical examination, nerve conduction studies, sympathetic skin response (SSR) and skin wrinkling stimulated by water and EMLA (eutectic mixture of local anaesthetics). RESULTS: Of 21 patients, 16 (76%) had low IENFD, 15 (71%) impaired water-induced wrinkling, 14 (67%) impaired EMLA-induced wrinkling, and nine (43%) abnormal SSR. CONCLUSIONS: Stimulated skin wrinkling was nearly as sensitive as IENFD in diagnosing SFN, whereas SSR was of less use. Stimulated skin wrinkling is a useful supportive test when IENFD or other tests of small nerve fibre function are not available.

Epidermal transient receptor potential vanilloid 1 in idiopathic small nerve fibre disease, diabetic neuropathy and healthy human subjects.

AIMS: The transient receptor potential vanilloid 1 (TRPV1) plays an important role in mediating pain and heat. In painful neuropathies, intraepidermal TRPV1 nerve fibre expression is low or absent, suggesting that pain generated is not directly related to sensory nerve fibres. Recent evidence suggests that keratinocytes may act as thermal receptors via TRPV1. The aim was to investigate epidermal TRPV1 expression in patients with neuropathic conditions associated with pain. METHODS AND RESULTS: In a prospective study of distal small nerve fibre neuropathy (DISN; n = 13) and diabetic neuropathy (DN; n = 12) intraepidermal nerve fibre density was assessed using the pan axonal marker PGP 9.5 and epidermal TPVR1 immunoreactivity compared with controls (n = 9). Intraepidermal nerve fibres failed to show TRPV1 immunoreactivity across all groups. There was moderate and strong TRPV1 reactivity of epidermal keratinocytes in 41.8% and 6% for DISN, 32.9% and 2.9% for DN and 25.4% and 5.1% for controls, respectively. Moderate keratinocyte TRPV1 expression was significantly increased in DISN compared with controls (P = 0.01). CONCLUSION: Our study suggests that in human painful neuropathies, epidermal TRPV1 expression is mainly in keratinocytes.

Second lumbrical-interossei latency difference: A strong predictor of median neuropathy at the wrist in uremic patients.

PURPOSE: Hand symptoms in uremic patients on dialysis can occur due to peripheral neuropathy, median neuropathy at wrist (carpal tunnel syndrome) or a combination. Routine electrophysiological parameters for diagnosing carpal tunnel syndrome do not differentiate median neuropathy at wrist in cases with concomitant peripheral neuropathy. Measuring 2L-INT latency difference has been described as the most sensitive test in establishing median neuropathy at wrist in cases with severe carpal tunnel syndrome and concomitant peripheral neuropathy. This study tested the significance of 2L-INT latency difference as a predictor of median neuropathy at wrist in uremic patients on dialysis. METHODS: 80 consecutive cases (158 hands) of end-stage renal failure on either hemodialysis or peritoneal dialysis were subjected to routine electrophysiological studies for carpal tunnel syndrome. 2L-INT latency difference was measured in all cases. RESULTS: 132/158 hands (83.5%) had abnormal electrophysiological studies. Routine tests were consistent with neurophysiological carpal tunnel syndrome in 66 (41.8%) hands and 63 of these 66 (95.5%) had prolonged 2L-INT latency difference. Peripheral neuropathy was found in 66 (41.8%) hands but 59 out of these 66 (89.4%) had prolonged 2L-INT latency difference suggesting a concomitant median neuropathy at wrist. Routinely performed tests would have missed median neuropathy at wrist with concomitant peripheral neuropathy in 59 (37.3%) hands. Overall, the incidence of median neuropathy at the wrist in our uremic patients on maintenance dialysis using standard nerve conduction parameters was 41.8%, however the incidences increased substantially to 79.1% if 2L-INT latency difference is included in the criteria for the diagnosis. CONCLUSIONS: Median neuropathy at wrist is common in patients with end-stage renal failure patients on dialysis. Diagnosis of median neuropathy at wrist is difficult in the presence of peripheral neuropathy when using the routine electrophysiological tests. Second Lumbrical-Interossei latency difference is a sensitive electrophysiological test to predict median neuropathy at wrist in presence of peripheral neuropathy.

The median palmar cutaneous nerve in normal subjects and CTS.

OBJECTIVE: The neurophysiological confirmation of carpal tunnel syndrome (CTS) relies on detecting abnormal median nerve transcarpal conduction in the presence of unaffected comparator nerves. We compare the palmar cutaneous median branch (PCBm) with the ulnar sensory nerve conduction to digit 5 (US(5)) as comparator nerves for diagnosing CTS. METHODS: In a prospective case control study of patients with clinically defined carpal tunnel syndrome and normal subjects, we determined and compared the PCBm and US(5) conduction velocity. RESULTS: We examined 57 hands with clinically defined CTS and 59 control hands. Comparison showed highly significantly slowed PCBm conduction (p<0.0001) but not for US(5) conduction (p=0.488). Using a 3 percentile cut-off for abnormality derived from controls, PCBm conduction velocity was abnormal in 46% of CTS hands. CONCLUSIONS: The high frequency of PCBm nerve conduction abnormality in CTS suggests that this nerve should not be used as a comparator nerve for the neurophysiological diagnosis of CTS. This finding may help explain some of the extension of sensory symptoms outside the median nerve distribution in CTS. SIGNIFICANCE: In CTS frequent abnormality of PCBm conduction makes this a poor comparator nerve and may explain extension of sensory symptoms beyond the median nerve.

Symptoms associated with electrophysiologically verified carpal tunnel syndrome in Asian patients.

Sensory symptoms are crucial for the diagnosis of carpal tunnel syndrome (CTS). We have studied the spectrum of sensory symptoms in 67 cases of neurophysiologically confirmed CTS in Singapore and investigated the correlation of semi-quantitative clinical ('Historical-Objective') and neurophysiological ('Bland') scales. The range of sensory symptoms was large. The more frequent use of the terms 'woodenness' and 'aching' rather than 'pins and needles' suggests racial and cultural differences in symptom expression, or recognition of previously ignored descriptors. 'Numbness' (97%) was the most common descriptive symptom, followed by 'tingling' (81%), 'tightness' (60%), 'aching' (45%), 'woodenness' (39%) and 'pins and needles' (33%). Less common were 'deadness' (27%), prickling (24%), and cramp-like pain (18%). Uncommon sensations included 'jabbing' (10%), 'shooting pain' (10%), 'stabbing' (9%), 'tight-band like pressure' (9%), 'cold' (8%), 'crushing' (6%) and 'burning' (6%). The semi-quantitative clinical and neurophysiological scales correlated well (Pearson 0.645, P<0.001).