Reduced association between dendritic cells and corneal sub‐basal nerve fibers in patients with fibromyalgia syndrome

In our study, we aimed at investigating corneal langerhans cells (LC) in patients with fibromyalgia syndrome (FMS) and small fiber neuropathy (SFN) as potential contributors to corneal small fiber pathology. We enrolled women with FMS (n = 134) and SFN (n = 41) who underwent neurological examination, neurophysiology, prostaglandin analysis in tear fluid, and corneal confocal microscopy (CCM). Data were compared with those of 60 age‐matched female controls. After screening for dry eye disease, corneal LC were counted and sub‐classified as dendritic (dLC) and non‐dendritic (ndLC) cells with or without nerve fiber association. We further analyzed corneal nerve fiber density (CNFD), length (CNFL), and branch density (CNBD). Neurological examination indicated deficits of small fiber function in patients with SFN. Nerve conduction studies were normal in all participants. Dry eye disease was more prevalent in FMS (17%) and SFN (28%) patients than in controls (5%). Tear fluid prostaglandin levels did not differ between FMS patients and controls. While corneal LC density in FMS and SFN patients was not different from controls, there were fewer dLC in association with nerve fibers in FMS and SFN patients than in controls (P < .01 each). Compared to controls, CNFL was lower in FMS and SFN patients (P < .05 each), CNFD was lower only in FMS patients (P < .05), and CNBD was lower only in SFN patients (P < .001). There was no difference in any CCM parameter between patients with and without dry eyes. Our data indicate changes in corneal innervation and LC distribution in FMS and SFN, potentially based on altered LC signaling.     

Corneal confocal microscopy: A novel means to detect nerve fibre damage in idiopathic small fibre neuropathy

Patients with idiopathic small fibre neuropathy (ISFN) have been shown to have significant intraepidermal nerve fibre loss and an increased prevalence of impaired glucose tolerance (IGT). It has been suggested that the dysglycemia of IGT and additional metabolic risk factors may contribute to small nerve fibre damage in these patients.Twenty-five patients with ISFN and 12 aged-matched control subjects underwent a detailed evaluation of neuropathic symptoms, neurological deficits (Neuropathy deficit score (NDS); Nerve Conduction Studies (NCS); Quantitative Sensory Testing (QST) and Corneal Confocal Microscopy (CCM)) to quantify small nerve fibre pathology.Eight (32%) patients had IGT. Whilst all patients with ISFN had significant neuropathic symptoms, NDS, NCS and QST except for warm thresholds were normal. Corneal sensitivity was reduced and CCM demonstrated a significant reduction in corneal nerve fibre density (NFD) (P < 0.0001), nerve branch density (NBD) (P < 0.0001), nerve fibre length (NFL) (P < 0.0001) and an increase in nerve fibre tortuosity (NFT) (P < 0.0001). However these parameters did not differ between ISFN patients with and without IGT, nor did they correlate with BMI, lipids and blood pressure.Corneal confocal microscopy provides a sensitive non-invasive means to detect small nerve fibre damage in patients with ISFN and metabolic abnormalities do not relate to nerve damage.     

Quantitative Sensory Testing in Patients With Chronic Unilateral Radicular Neuropathic Pain and Active Spinal Cord Stimulation

Objectives. Spinal cord stimulation (SCS) is an effective treatment option for chronic radicular neuropathic pain syndromes. This prospective study was performed to examine the peripheral effects of SCS on sensation using quantitative sensory testing (QST). Materials and Methods. We measured two consecutive QST measurements for thermal, tactile‐static, tactile‐dynamic, vibratory, and pain sensation of the lower limbs in seven patients with chronic unilateral radicular neuropathic pain who underwent SCS implantation for their pain. Measurements were performed when SCS was turned off and once again during SCS and subsequent reduced pain levels. Results. Baseline QST demonstrated significantly increased thresholds for tactile and warm and cold detection in the pain area. With SCS active, a significant reduction of the cold and warm perception and mechanical detection thresholds was found on the painful side (p < 0.01). Although not significant (p > 0.01), altered sensory thresholds with active SCS also were found at the healthy side where no paresthesias were felt. Conclusion. SCS leads to bilateral subclinical effects even if the evoked paresthesias are only unilateral. Pain perception thresholds are not altered with therapeutic SCS.     

Enzyme replacement therapy improves peripheral nerve and sweat function in Fabry disease

Fabry disease is an X-linked disorder caused by a deficiency of lysosomal alpha-galactosidase A resulting in accumulation of alpha-D-galatosyl conjugated glycosphingolipids. Clinical manifestations include a small-fiber neuropathy associated with debilitating pain and hypohidrosis. We report the effect of a 3-year open-label extension of a previously reported 6-month placebo-controlled enzyme replacement therapy (ERT) trial in which 26 hemizygous patients with Fabry disease received 0.2 mg/kg of alpha-galactosidase A every 2 weeks. The effect of ERT on neuropathic pain scores while off pain medications, quantitative sensory testing, quantitative sudomotor axon reflex test (QSART), and thermoregulatory sweat test (TST) is reported. In the patients who crossed-over from placebo to ERT (n = 10), mean pain-at-its-worst scores on a 0-10 scale decreased (from 6.9 to 4.5). There was a significant reduction in the threshold for cold and warm sensation in the foot. At the 3-year time-point, pre-ERT sweat excretion in 17 Fabry patients was 0.24 +/- 0.33 microl/mm(2) vs. 1.05 +/- 0.81 in concurrent controls (n = 38). Sweat function improved 24-72 h post-enzyme infusion (0.57 +/- 0.71 microl/mm(2)) and normalized in four anhidrotic patients. TST confirmed the QSART results. We conclude that prolonged ERT in Fabry disease leads to a modest but significant improvement in the clinical manifestations of the small-fiber neuropathy associated with this disorder. QSART may be useful to further optimize the dose and frequency of ERT.     

Dyshidrosis is associated with reduced amplitudes in electrically evoked pain-related potentials in women with Fabry disease

ObjectiveTo investigate A-delta fiber conduction in mild to moderate Fabry disease (FD) patients using pain-related evoked potentials (PREP).MethodsIn this case-control study we prospectively investigated 58 patients with mild to moderate FD and compared data with those of healthy controls. Small fiber function (quantitative sensory testing, QST and sympathetic skin response, SSR), morphology (intraepidermal nerve fiber density, IENFD), and electrical conduction (PREP) were assessed and correlated with sweating as major autonomic function disturbed in FD. Patients were further stratified for gender, disease severity as reflected by renal and cardiac function, and genetics.ResultsAn- or hypohidrosis (i.e. dyshidrosis) was reported by 7/32 (22%) women and 15/26 (58%) men with FD (p < 0.01). QST showed small fiber impairment in female and male patients regardless of clinical symptoms, while SSR was obtained in all patients except one man with hypohidrosis. IENFD was reduced in 50% of FD patients, with no differences between groups with and without autonomic symptoms. However, PREP amplitudes were reduced independent of the stimulation site only in female patients with dyshidrosis (p < 0.01). Genetics had no influence on PREP parameters.ConclusionA-delta fiber conduction investigated using PREP is impaired in mild to moderately affected female FD patients with clinical signs of hypohidrosis.SignificanceSmall fiber assessment in FD is of diagnostic value already in mild to moderate stages of disease.     

Vestibular and auditory deficits in Fabry disease and their response to enzyme replacement therapy

Progressive hearing (pHL) and vestibular (pVL) loss are frequent deficits in Fabry disease (FD). Recently, enzyme replacement therapy (ERT) with human α-galactosidase A has become available. Here, we investigate the association between pHL and pVL in FD and their ERT responses. Pure tone audiometry (PTA) and head impulse testing (HIT) were administered at baseline in 47 patients (25 male, 18–60 y; 22 female, 17–74 y), of whom 24 also received caloric irrigation (CI). Of the 47 patients, 38 (24 male) were tested both before and during ERT (follow- up ≤ 60 months). ERT consisted of agalsidase alfa infusions. At baseline, pHL was present in 88% of males and 86% of females. Over all tested frequencies (range: 0.5–6 kHz), pHL was significantly (two-way ANOVA: p < 0.05) greater at higher age and in males,with largest deficits at high frequencies. When assessed with HIT, 80% of males and 77% of females had pVL. pVL was significantly greater at higher age and in males. Tested with CI, 21% of males and 0% of females had pVL. No associations among individual semicircular canal (SCC) deficits, as tested by HIT, and hearing was observed in individual ears. After ≥ 18 months of ERT, pVL was significantly smaller than at baseline (ANOVA for HIT: p < 0.01). In contrast, pHL remained unchanged by ERT over 60 months (p > 0.05). We conclude that pHL and pVL prevalences are similar in FD. To detect pVL, HIT is more sensitive than CI. We speculate that pHL and pVL emerge from lesions within the vestibulocochlear labyrinth, because no specific patterns of vestibulo-cochlear deficits were observed, as expected if lesions were more proximal along the inferior or superior branch of the vestibulo-cochlear nerve or labyrinthine artery. Finally, ERT stabilizes auditory and even improves vestibular function. Grant/financial support: Swiss National Science Foundation (#3200B0–105434); Betty and David Koetser, Foundation for Brain Research, Zurich, Switzerland.     

Upregulation of inward rectifying currents and Fabry disease neuropathy

Peripheral neuropathy and neuropathic pain are common clinical manifestations of Fabry disease (FD). Although the mechanisms underlying the development of sensory neuropathy remain to be fully elucidated, a chronic ischemic process was proposed. Consequently, this study utilized axonal excitability techniques to gain further insights into the pathophysiological mechanisms underlying the development of FD neuropathy. Median motor and sensory axonal excitability studies were undertaken in 13 FD patients and results were compared to 19 healthy subjects. A “fanning‐in” of threshold electrotonus, suggestive of membrane depolarization, was evident only in motor axons in FD patients. In contrast, the sensory axons exhibited a lower threshold in FD (p < 0.05) and a significantly increased hyperpolarizing current/threshold (I/V) gradient (FD 0.48 ± 0.03; controls, 0.31 ± 0.02, p < 0.001), which correlated with clinical scores of disease severity (Rho = 0.65, p < 0.05), neuropathy (Rho = 0.54, p < 0.05) and neuropathic pain (Rho = 0.56, p < 0.05). These findings indicate that upregulation of I_h, rather than ischemia, may underlie the sensory symptoms and possibly development of neuropathy in FD. Modulation of sensory I_h may prove therapeutically useful in Fabry disease.     

Neuropathy and Fabry disease: pathogenesis and enzyme replacement therapy

The neurological manifestations of Fabry disease include both peripheral and central nervous system involvement caused by a deficiency of alpha-galactosidase A and accumulation of alpha-D-galactosyl moieties, particularly globotriosylceramide accumulation (Gb3). These are found in Schwann cells and dorsal root ganglia together with deposits in central nervous system neurons. Involvement of the peripheral nervous system affect mainly small Adelta and C fibers and are likely causally related to the altered autonomic function and neuropathic pain found in this disorder. Other related abnormalities to be discussed are hypohidrosis and other abnormalities attributed to autonomic nervous system dysfunction. The function of the peripheral nervous system is somewhat improved by ERT with reduction in neuropathic pain and an improvement of the detection threshold for cold and warm sensation in the hand and foot. Improvement in sweating and heat tolerance is also noted following ERT. Despite those positive results, ERT does not normalize the function of the peripheral nervous system.     

Corneal confocal microscopy reveals small nerve fibre loss correlating with motor function in adult spinal muscular atrophy

Background

5q Spinal muscular atrophy (SMA) is a progressive, inherited, and severely disabling – yet treatable – motor neuron disease. Although treatment options have evolved in recent years, biomarkers for treatment monitoring and prognosis prediction remain elusive. Here, we investigated the utility of corneal confocal microscopy (CCM), a non-invasive imaging technique to quantify small corneal nerve fibres in vivo, as a diagnostic tool in adult SMA.

Methods

In this cross-sectional study, 19 patients with SMA type 3 and 19 healthy controls underwent CCM to measure corneal nerve fibre density (CNFD), corneal nerve fibre length (CNFL), and corneal nerve branch density (CNBD), as well as corneal immune cell infiltration. Hammersmith Functional Motor Scale Expanded (HFMSE) and Revised Upper Limb Module (RULM) scores and a 6-Minute Walk Test (6MWT) were conducted to explore any correlation between CCM findings and motor function.

Results

Corneal nerve fibre parameters were decreased in SMA patients versus healthy controls (CNFD: p = 0.030; CNFL: p = 0.013; CNBD: p = 0.020) in the absence of relevant immune cell infiltration. CNFD and CNFL correlated with HFMSE scores (CNFD: r = 0.492, p = 0.038; CNFL: r = 0.484, p = 0.042) and distance covered in the 6MWT (CNFD: r = 0.502, p = 0.042; CNFL: r = 0.553, p = 0.023).

Conclusions

Corneal confocal microscopy CCM reveals sensory neurodegeneration in SMA, thereby supporting a multisystem view of the disorder. Subclinical small nerve fibre damage correlated with motor function. Thus, CCM may be ideally suited for treatment monitoring and prognosis.     

One‐year follow‐up study of neuropathic pain in chronic inflammatory demyelinating polyradiculoneuropathy

We sought to gather information about frequency and features of neuropathic pain (NeP) in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) patients and to investigate course of NeP during 1‐year follow‐up. Study included 105 patients diagnosed with CIDP. Patients with diabetes (N = 26) were excluded. NeP was diagnosed by the official guidelines and painDETECT questionnaire (PD‐Q). Medical Research Council Sum Score (MRC‐SS), INCAT disability and sensory scores, and Beck Depression Inventory were also measured. PD‐Q showed presence of NeP in 16 (20%) of 79 CIDP patients and their mean pain was moderate (5.1 ± 3.0 of 10). Diagnostic delay in CIDP patients with NeP was prolonged compared to CIDP patients without NeP (21 ± 28 vs 9 ± 12 months, P < .05). Slowly progressive course of the disease was more frequent in patients with NeP (81% vs 52%, P < .05). Patients with NeP had worse INCAT sensory score (P < .01), INCAT disability score (P < .05), MRC‐SS, as well as worse disease outcome at time of testing (P < .05). Depression was more common in patients with NeP (69% vs 17%, P < .01). During 1‐year follow‐up, majority of our CIDP patients had good control of NeP with gabapentinoids or amitriptyline. NeP was common in our cohort of non‐diabetic CIDP patients. It was associated with worse functional disability, worse sensory deficit, and depression. Special attention should be paid to CIDP patients with NeP because they request additional symptomatic therapy that appeared efficacious in our cohort.     

Paradoxical heat sensation in uremic polyneuropathy

Sensory aspects of uremic neuropathy were studied in 36 patients using clinical assessment and quantitative sensory tests (QST). The outstanding abnormality in sensory quality was perception of heat in response to low temperature stimuli. This paradoxical heat sensation was found in the foot in 42% (15) of patients, far beyond the normal prevalence of 10%. Paradoxical sensation was positively related to cold hypoesthesia (P = 0.0004) suggesting disinhibition as a possible mechanism. Paradoxical heat sensation also positively related to creatinine level (P = 0.0012). Pruritus was present in 20 patients (56%), intensity not related to any biochemical or clinical parameter. Signs of sensory polyneuropathy (PNP), based on at least two abnormal parameters in the clinical assessment or QST, were found in 39% of patients (14), of whom 11 had paradoxical heat sensation. Thus, in 4 patients (11%), this sensory aberration preceded other signs for PNP. Paradoxical heat sensation seems to be a common and often early expression of the sensory neuropathy in uremia. © 1995 John Wiley & Sons, Inc.     

Contribution of clinical screening to carrier detection in a large Chinese family with fabry disease due to a novel alpha-galactosidase A gene deletion

Diagnosis of heterozygous Fabry patients is difficult because of its variable clinical manifestations and overlapping serum α -galactosidase A (AGA) activity between carriers and non-carriers. We tried to facilitate diagnosis of heterozygous Fabry patients by detailed clinical examination. We analyzed clinical presentations, biochemical, electrophysiological and genetic characteristics of 16 patients with Fabry disease in a large Chinese family.
Male patients demonstrated significantly higher pain scores, poorer renal function, and higher frequency of hypohidrosis and corpora angiokeratomas than female patients. Interestingly, all the males and females had corneal verticilata by slit lamp examination. However, there was no association of serum AGA activity with renal function or pain symptom scores. The results indicated that detailed ocular and neurological examination might provide an alternative way of detecting heterozygous patients. We also report a novel large deletion spanning across the joint of Alu repetitive elements in introns 1 and 2 with resultant exon 2 deletion in a Chinese family with Fabry disease.     

Small fibers in Fabry disease: baseline and follow-up data under enzyme replacement therapy

Fabry disease (FD) is an X-linked lysosomal storage disorder which may lead to impaired peripheral nerve function, mostly affecting small nerve fibers, and to neuropathic pain. Characteristics of the neuropathy associated with FD and the covariates for its development and temporal course have not been described in a large cohort. We studied small fiber function and morphology in 120 Fabry patients at baseline and in subgroups of these until 4-year follow-up. Baseline neurological (89/120) and electrophysiological (106/120) examination was mostly normal. Quantitative sensory testing revealed impaired cold detection thresholds in 84% of men and 39% of women. Lower leg intraepidermal nerve fiber density (IENFD) was reduced to 46% in Fabry patients compared to controls and to 12.5% in men with impaired renal function. Patients with abnormal IENFD more often had pain. Group means for IENFD did not improve under enzyme replacement therapy (ERT), but IENFD in the back increased under ERT in 4/15 patients with good renal function and clinical improvement. Cutaneous cytokine gene expression did not differ from controls. We conclude that ERT may improve proximal skin innervation in patients with good renal function, but does not protect small fiber function in men with impaired renal function.     

High‐resolution colonic manometry accurately predicts colonic neuromuscular pathological phenotype in pediatric slow transit constipation

Background Severe pediatric slow transit constipation (STC) is commonly due to intrinsic colonic neuromuscular disease. We sought to correlate neuromuscular histological phenotypes in pediatric STC with colonic manometric phenotypes using high‐resolution manometry (HRM). We tested the hypothesis that failure of motor quiescence (FQ) between bisacodyl‐induced high amplitude propagating sequences (HAPSs) might predict neuromuscular pathology. Methods Eighteen children (10 males, median age: 7.5 years) with refractory STC underwent stationary colonic HRM before segmental colonic resection. Six age‐matched constipated children with normal colonic transit served as controls. Colonic resection specimens underwent histopathological analysis. Conventional manometric parameters and area under the curve (AUC) during a 1‐min period following bisacodyl‐induced HAPSs [PBAUC₁], as measure of FQ, were calculated. Key Results Numbers of postbisacodyl HAPSs in descending and sigmoid segments were lower in patients than controls (P < 0.01, respectively). Low amplitude propagating sequences (LAPSs) were common prebisacodyl in controls and rare in STC (P < 0.001), whereas postbisacodyl LAPS were more common in STC (P < 0.001). Postbisacodyl, both retrograde propagating contractions and bursts of contractions were present in STC patients only (P < 0.001 and P < 0.01). Postbisacodyl simultaneous pressurization was seen only in STC (P < 0.05 and P < 0.001, in descending and rectosigmoid segments). Histological abnormalities were present in 17/18. Fourteen were neurogenic, one neuro‐myogenic, and two myogenic. In segments with HAPS, PBAUC₁ was predictive of colonic neuropathy using a cutoff of 205 mmHg.s^‐1 (Sensitivity 100%, specificity 86%, PPV92%, NPV100%). Conclusions & Inferences PBAUC₁ is increased in multiple colonic segments in neuropathic pediatric STC and constitutes a sensitive and specific biomarker of neuropathy.     

Dissociation between cutaneous silent period and laser evoked potentials in assessing neuropathic pain

In this study we investigate whether the cutaneous silent period (CSP)—an inhibitory response evoked in hand muscles by painful digital nerve stimulation—is useful for assessing nociceptive pathway function in patients with neuropathic pain. In 40 patients with peripheral neuropathy (21 without and 19 with neuropathic pain) we recorded the CSP in the abductor digiti minimi after fifth digit stimulation and also recorded laser evoked potentials (LEPs) after stimulation applied to the ulnar territory of the hand. Although the LEP amplitude was significantly lower in patients with pain than in those without (P < 0.005), the CSP duration did not differ between groups (P > 0.50). Pain intensity correlated significantly with LEP amplitudes (P < 0.005) but not with CSP duration (P > 0.5). Our findings indicate that the CSP is not useful for assessing nociceptive pathway function in patients with neuropathic pain. Muscle Nerve, 2008     

Association of corneal nerve loss with markers of axonal ion channel dysfunction in type 1 diabetes

ObjectiveCorneal confocal microscopy (CCM) has been identified as a non-invasive technique to assess corneal nerve fiber morphology. It is not known how corneal nerve changes relate to measures of peripheral nerve function in diabetic peripheral neuropathy (DPN). The present study investigates the relationship between nerve structure and function in DPN.MethodsFifty participants with type 1 diabetes (T1DM) and 29 healthy controls underwent CCM to assess corneal nerve fiber density (CNFD), branch density (CNBD), fiber length (CNFL), total branch density (CTBD), nerve fractal dimension (CNFrD) and inferior whorl length (IWL). The severity of DPN was assessed as Total Neuropathy Score (TNS). Motor nerve axonal excitability tests were conducted to assess axonal function.ResultsSignificant correlations were noted between CNFD (rho = −0.783; P < 0.01) or superexcitability (rho = 0.435; P < 0.01) and TNS. CNFrD was significantly correlated with peak response to stimulus (r = 0.414; P < 0.01) and superexcitability (r = −0.467; P < 0.01) measurements.ConclusionCorneal nerve loss demonstrates a significant association with axonal ion channel dysfunction in T1DM.SignificanceDetection of altered corneal nerve morphology may lead to the earlier diagnosis of DPN.     

Real world,open label experience with lacosamide against acute painful oxaliplatin‐induced peripheral neurotoxicity

We report the outcome of a pilot, open‐label study that tested the potential of lacosamide (200 mg/bi.d) as an effective and safe symptomatic treatment against acute painful oxaliplatin‐induced peripheral neurotoxicity (OXAIPN). Lacosamide was introduced in 18 colorectal cancer patients with evidence of clinically significant acute, painful OXAIPN after infusion of the third course (T1) of oxaliplatin‐based chemotherapy (FOLFOX4) and was maintained until completion of all 12 courses (T4). The OXA‐Neuropathy Questionnaire (OXA‐NQ) was used to record the severity of acute OXAIPN; the PI‐NRS estimated the severity of neuropathic pain, while the chronic OXAIPN was graded with TNSc. The EuroQOL ( EQ‐5D) instrument was also applied. The Patient Global Impression of Change (PGIC) scale measured the lacosamide‐attributed perception of change. LCM‐responders were considered those with ≥50% reduction in PI‐NRS and OXA‐NQ scores at T4, compared to T1. Patients experienced on T1 a median number of acute OXAIPN symptoms of 4 and had a median neuropathic pain severity score of 6, which was strongly related to lower quality of life, according to EQ‐VAS (P < .001). At T4, 12 patients (66.7%) were classified as responders. A significant clinical improvement was documented in the severity of acute OXAIPN and neuropathic pain in relation to lacosamide (P < .001) at T4 compared to T1, which was associated with improved EQ‐VAS scores (P < .001). Twelve patients scored PGIC ≥5 (lacosamide‐attributed) at T4. There were no incidences of early drop‐outs for safety reasons. Lacosamide appears to be an effective and well‐tolerated symptomatic treatment against acute, painful OXAIPN.     

Enzyme replacement therapy and intraepidermal innervation density in Fabry disease

We prospectively evaluated the effect of enzyme replacement therapy (ERT) on the intraepidermal nerve fiber density (IENFD) and thermal threshold in patients with Fabry disease, an X-linked disorder associated with a painful small-fiber neuropathy and decreased linear IENFD in a length-dependent pattern. Twenty-five hemizygous male patients with Fabry disease were enrolled in a 6-month, randomized, placebo-controlled ERT trial of 0.2 mg/kg of alpha-galactosidase A (agalsidase-alfa) every 2 weeks followed by an additional 12 months of open-label ERT for both populations. IENFD and thermal threshold were measured in the distal thigh at baseline, 6 months, and 18 months from initiation of the trial. We found no significant difference in IENFD between the treatment groups at 6 months. After an additional year of ERT, there was a significant reduction in IENFD in the patient group as a whole, attributable to the declining glomerular filtration rate. Thermal thresholds remained unchanged. We conclude that epidermal nerve fiber regeneration, as measured in the distal thigh, does not occur in this patient population after 12-18 months of ERT.     

Association of muscle strength and electrophysiological measures of reinnervation in diabetic neuropathy

Motor function was assessed in 34 non-insulin-dependent and 19 insulin-dependent diabetic patients with macroelectromyography and isokinetic dynamometry. Fiber density (FD) and the amplitude of the macro motor unit potential (macro MUP) of the anterior tibial and lateral vastus muscles were obtained and maximal isokinetic strength of the ankle and knee extensors were determined. All patients underwent standardized clinical examination including a neurological disability score (NDS), quantitative sensory examination, and conventional motor nerve conduction studies. The amplitude of the macro MUP and FD of the anterior tibial muscle were increased in neuropathic patients without weakness (P < 0.05) and further increased in neuropathic patients with weakness (P < 0.05). The NDS was related to the FD and the amplitude of the macro MUP for the anterior tibial and lateral vastus muscle [r = 0.55–0.75 (P < 0.005)]. Muscle strength of ankle and knee extensors correlated with the FD [r = −0.69 (P < 0.0001) and r = −0.58 (P < 0.001), respectively] and with the amplitude of the macro MUP of the two muscles [r = −0.63 (P < 0.0001) and r = −0.37 (P < 0.05), respectively]. Our findings support the hypothesis that loss of muscle strength in diabetic patients is due to incomplete reinnervation following axonal loss. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 1647–1654, 1998     

Ultrasound assessment of the sural nerve in patients with neuropathic pain after ankle surgery

Introduction: The sural nerve may be damaged after ankle injury. The aim of our study was to determine the diagnostic utility of high‐resolution sonography in patients with ankle fractures treated by open reduction and internal fixation in whom there was a clinical suspicion of sural neuropathy. Methods: We examined the ultrasound (US) characteristics of patients with and without postsurgical sural neuropathic pain and healthy volunteers. Cross‐sectional area (CSA), echogenicity, and vascularization of the sural nerves were recorded. Results: Fourteen participants and all sural nerves were identified. CSA (P < 0.001) and vascularization (P = 0.002) were increased in symptomatic patients when compared with asymptomatic patients and healthy volunteers. There were no significant differences in nerve echogenicity (P = 0.983). Discussion: US may be a valuable tool for evaluating clinically suspected sural nerve damage after ankle stabilization surgery. Sural nerve abnormalities are seen in patients with postsurgical neuropathic pain. Muscle Nerve 57 : 407–413, 2018