Pathological Spontaneous Activity Research Articles

Intravoxel Incoherent Motion Diffusion-Weighted MRI, Fat Quantification, and Electromyography: Correlation in Polymyositis and Dermatomyositis.

(1) Background: The intravoxel incoherent motion (IVIM) model can provide information about both molecular diffusion and blood flow for the evaluation of skeletal muscle inflammation. MRI-based fat quantification is advantageous for assessing fat infiltration in skeletal muscle. (2) Purpose: We aimed to quantitatively measure various parameters associated with IVIM diffusion-weighted imaging (DWI) and fat quantification in the muscles of patients with polymyositis and dermatomyositis using magnetic resonance imaging and to investigate the relationship between these parameters and electromyography (EMG) findings. (3) Material and methods: Data were retrospectively evaluated for 12 patients with polymyositis and dermatomyositis who underwent thigh MRI, including IVIM-DWI and fat quantification. The IVIM-derived parameters included the pure diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f). Fat fraction values were assessed using the six-point Dixon technique. Needle EMG was performed within 9 days of the MRI. (4) Results: The f values (19.02 ± 4.87%) in muscles with pathological spontaneous activity on EMG were significantly higher than those (14.60 ± 5.31) in muscles without pathological spontaneous activity (p < 0.027). There were no significant differences in D, D*, ADC, or fat fraction between muscles with and without pathologic spontaneous activity. Significant negative correlations were observed between fat fraction and amplitude (r = -0.402, p < 0.015) and between fat fraction and duration (r = -0.360, p < 0.031). (5) Conclusion: The current study demonstrates that IVIM-DWI and fat quantification using 3.0 T MRI may aid in predicting EMG findings in patients with polymyositis and dermatomyositis and promote the pathophysiological study of idiopathic inflammatory myopathies.

Segmental infralesional pathological spontaneous activity in subacute traumatic spinal cord injury.

There is a dearth of knowledge regarding the status of infralesional lower motor neurons (LMNs) in individuals with traumatic cervical spinal cord injury (SCI), yet there is a growing need to understand how the spinal lesion impacts LMNs caudal to the lesion epicenter, especially in the context of nerve transfer surgery to restore several key upper limb functions. Our objective was to determine the frequency of pathological spontaneous activity (PSA) at, and below, the level of spinal injury, to gain an understanding of LMN health below the spinal lesion. Ninety-one limbs in 57 individuals (53 males, mean age = 44.4 ± 16.9 years, mean duration from injury = 3.4 ± 1.4 months, 32 with motor complete injuries), were analyzed. Analysis was stratified by injury level as (1) C4 and above, (2) C5, and (3) C6-7. Needle electromyography was performed on representative muscles innervated by the C5-6, C6-7, C7-8, and C8-T1 nerve roots. PSA was dichotomized as present or absent. Data were pooled for the most caudal infralesional segment (C8-T1). A high frequency of PSA was seen in all infralesional segments. The pooled frequency of PSA for all injury levels at C8-T1 was 68.7% of the limbs tested. There was also evidence of PSA at the rostral border of the neurological level of injury, with 58.3% of C5-6 muscles in those with C5-level injuries. These data support a high prevalence of infralesional LMN abnormalities following SCI, which has implications to nerve transfer candidacy, timing of the intervention, and donor nerve options.

EMG phenomena of myogenic hyperexcitability

The type, distribution pattern and time course of spontaneous muscular activity are important for the diagnostics of neuromuscular diseases in the clinical practice. In neurogenic lesions with motor axonal involvement, pathologic spontaneous activity (PSA) is usually reliably detectable by needle electromyography (EMG) 2-4weeks after occurrence of the lesion. The distribution pattern correlates with the lesion location. The focus of the present work is the description of the different forms of PSA in myogenic diseases.

Coxofemoral luxation as a complication of localised tetanus in a cat

Case summaryA 9-month-old male neutered domestic shorthair cat presented 2 weeks after castration with a 48 h history of acute-onset lateral recumbency and severe hindlimb rigidity. Physical examination findings included hyperthermia, tachypnoea, hindlimb rigidity and a healed orchidectomy site. Neurological examination of the head and forelimbs was normal; however, there was a spastic, non-ambulatory paraparesis of the hindlimbs, which was more severe on the left. Abnormal findings included mildly elevated serum creatine kinase levels and on electromyography there was bilateral pathological spontaneous activity of the biceps femoris muscles. A tentative diagnosis of tetanus was made based on clinical presentation. Treatment was initiated with tetanus antitoxin, diazepam, metronidazole, buprenorphine and physiotherapy of the hindlimbs. There was an improvement over the following 20 days. Twenty-five days later the cat presented with acute, painful, non-weightbearing lameness of the left hindlimb. Physical examination was suggestive of craniodorsal coxofemoral joint luxation, which was confirmed radiographically. This was treated with analgesia and rest. A marked clinical improvement was observed at the 3-month follow-up.Relevance and novel informationTo our knowledge, there have been no previously published reports of spontaneous coxofemoral joint luxation as a complication of hindlimb localised tetanus infection in cats. This report suggests that coxofemoral luxation should be considered as a possible complication in young cats with hindlimb localised tetanus.

Corneal inflammatory cell infiltration predicts disease activity in chronic inflammatory demyelinating polyneuropathy

The assessment of disease activity is fundamental in the management of chronic inflammatory demyelinating polyneuropathy (CIDP). Previous studies with small patient numbers found an increase of corneal immune cell infiltrates as a potential marker of inflammation in patients with CIDP. However, its clinical relevance remained unclear. The present study aimed to determine whether the amount of corneal inflammatory cells (CIC) measured by corneal confocal microscopy (CCM) detects disease activity in CIDP. CIC were measured in 142 CCM-investigations of 97 CIDP-patients. Data on clinical disease activity, disability (INCAT-ODSS) and need for therapy escalation at the timepoint of CCM, 3 and 6 months later were analyzed depending CIC-count. Pathological spontaneous activity during electromyography was examined as another possible biomarker for disease activity in comparison to CIC-count. An increased CIC-count at baseline was found in patients with clinical disease activity and disability progression in the following 3–6 months. An increase to more than 25 CIC/mm2 had a sensitivity of 0.73 and a specificity of 0.71 to detect clinical disease activity and a sensitivity of 0.77 and a specificity of 0.64 to detect disability progression (increasing INCAT-ODSS) in the following 6 months. An increase to more than 50 CIC/mm2 had a sensitivity of about 0.51 and a specificity of 0.91 to detect clinical disease activity and a sensitivity of 0.53 and a specificity of 0.80 to detect disability progression. CIC count is a non-invasive biomarker for the detection of disease activity in the following 6 months in CIDP.

Hemihypoglossal-facial nerve anastomosis: results and electromyographic characterization.

The facial nerve surgery belongs to the basic procedures during lateral skull base approaches. Its damage has serious medical and psychological consequences, and therefore mastery of reconstruction and correction techniques should belong to the repertoire of skull base surgeons. The goal of this study was to demonstrate usefulness of electromyographic follow-up in facial nerve reconstruction. A total of 16 patients underwent hemihypoglossal-facial anastomosis between 2005 and 2017. Most of the primary lesions came from vestibular schwannoma surgery. All patients were examined with electromyography and scored according to the House-Brackmann and IOWA grading scales. Function of the tongue has been evaluated. Ten patients achieved definitive House-Brackmann grade 3 score (62.5%). We did not observe any association with the patient's age, previous irradiation and the etiology of the damage. Electromyography showed pathological spontaneous activity after the first surgery. Incipient regeneration potentials were detected in 4-17months (average 7.6) and reached maximum in 6.5-18months (average 16). Electromyographic assessment of the effect of tongue movement showed better mimic voluntary activity by swallowing or by moving the tongue up. There was no relationship between the start of activity and the interval to achieving maximal activity. Hemihypoglossal-facial nerve anastomosis is a safe procedure and it is an optimal solution for cases lacking a proximal stump or in the case of reconstruction in the second stage. Electromyography can predict initial reinnervation activity after reconstructive procedures. During subsequent follow-up it can help to discover insufficiently recovering patients, however clinical characteristics are crucial.

Pathological spontaneous activity as a prognostic marker in chronic inflammatory demyelinating polyneuropathy.

Monitoring of the disease course of patients with chronic inflammatory demyelinating polyneuropathy (CIDP) remains challenging because nerve conduction studies do not adequately correlate with functional disability. The prognostic value of pathological spontaneous activity (PSA) in needle electromyography (EMG) in different CIDP subgroups in a longitudinal context has, to date, not been analysed. We aimed to determine whether PSA was a prognostic marker or a marker of disease activity in a cohort of patients with CIDP. A total of 127 patients with CIDP spectrum disorder were retrospectively analysed over 57±47months regarding the occurrence of PSA (fibrillations and positive sharp waves). The presence of PSA at diagnosis, newly occurring PSA, and continuously present PSA were longitudinally correlated with clinical disability using the Inflammatory Neuropathy Cause and Treatment Overall Disability Sum Score (INCAT-ODSS) and CIDP subtype. Pathological spontaneous activity occurred in 49.6% of all CIDP patients at first diagnosis. More frequent evidence of PSA was significantly associated with a higher INCAT-ODSS at the last follow-up. Continuous and new occurrence of PSA were associated with higher degree of disability at the last follow-up. The majority of patients with sustained evidence of PSA were characterized by an atypical phenotype, higher degree of disability, and the need for escalation of treatment. Pathological spontaneous activity was associated with a higher degree of disability and occurred more frequently in atypical CIDP variants according to the longitudinal data of a large cohort of patients with CIDP. Our results showed that EMG examination was an adequate marker for disease progression and should be evaluated during the disease course.

Associations between magnetic resonance imaging and EMG findings in myopathies.

Magnetic resonance imaging (MRI) is a cornerstone in diagnosis of myopathies. The present study sought to elucidate possible associations between electromyography (EMG) findings and histogram parameters derived from clinical MRI in myositis and other myopathies. Twenty six patients with myopathies were included in this retrospective study. Clinical MRI was performed with a 1.5T MRI scanner including T2- and T1-weighted images. EMG analysis was performed during clinical diagnostic workup. The histogram parameters of the MRI sequences were obtained of the same muscle, which was investigated with EMG. Several correlations were identified between mean duration of the motor unit potentials (MUP) and histogram parameters derived from T1- and T2-weighted images. The highest for T1-weighted images was mode (r= -.73, P<.0001) and for T2-weighted images was p25 (r=-.57, P=.022). There were significant differences for several histogram parameters between muscles with pathological spontaneous activity and without. So, for T1-weighted images, the best discrimination was achieved with mean (P=.096), and for T2-weighted images for p10 (P=.05). Mean SI values derived from T1-weighted images achieved an AUC of 0.84 with a sensitivity of 0.81 and a specificity of 0.86 to discriminate patients with and without pathological spontaneous activity (PSA). The present study identified strong associations between histogram analysis derived from morphological MRI sequences and the duration of the MUP derived from EMG in myopathies strengthening the fact that both diagnostic modalities can reflect disease state in a similar fashion. Histogram parameters can predict muscles with PSA.

Prognostic factors for the outcome of Bells' palsy: A cohort register-based study.

There is a lack of data on patients' and diagnostic factors for prognostication of complete recovery in patients with Bell's palsy. Cohort register-based study of 368 patients with Bell's palsy and uniform diagnostics and standardised treatment in a university hospital from 2007 to 2017 (49% female, median age: 51years). Clinical data, facial grading, electrodiagnostics, motor function tests, non-motor function tests and onset of prednisolone therapy were assessed for their impact on the probability of complete recovery using univariable and multivariable statistics. Median onset of treatment was 1.5days. 46% of patients had a House-Brackmann scale at baseline of≥III. The median recovery time was 2.6months (95% confidence interval [CI]=2.1-3.0). 54.9% achieved a complete recovery. If prednisolone therapy started later than 96hours after onset, the recovery rate decreased significantly. Beyond less severe palsy, no abnormal electroneurography side difference, no pathological spontaneous activity in electromyography and normal stapedius reflex testing were the most powerful tool for prognostication of recovery after Bell's palsy. Beyond severity of the palsy, facial electrodiagnostics and stapedius reflex testing are the most powerful tool for prognostication of recovery time after Bell's palsy. Prednisolone therapy should have started at best within a time window of 96hours after onset to reach the highest probability of complete recovery.

FV6 Persistent pathological spontaneous activity in EMG is related to a worse outcome and atypical subtype in a cohort of CIDP patients

FV6 Persistent pathological spontaneous activity in EMG is related to a worse outcome and atypical subtype in a cohort of CIDP patients

Evaluation of Factors Associated With Favorable Outcomes in Adults With Bell Palsy

Identification of the factors associated with improved facial nerve function after treatment of Bell palsy is important to provide patients with early and effective treatment. To identify factors that are associated with improved treatment outcomes in patients with Bell palsy. This retrospective cohort study included 1364 patients with Bell palsy treated at the outpatient clinic of the Department of Otolaryngology at the Kyung Hee University Hospital, Seoul, Republic of Korea, between January 1, 2005, and December 31, 2017. The medical records of patients admitted to this hospital for management of acute facial palsy were reviewed by 3 otolaryngologists with more than 20 years' experience in treating facial palsy. Facial function at the initial and final visits were measured using the House-Brackmann (H-B) grading system, which is one of several analysis tools developed to quantify facial function and provide reproducible information. It is a widely accepted system for grading facial function in 6 steps, from normal (H-B grade I) to total paralysis (H-B grade VI). In total, 1364 patients with primary Bell palsy (718 [52.6%] women) and a mean (SD) age of 47.7 (16.7) years were enrolled. The overall rate of favorable outcome, which was defined as an H-B grade of I or II at the 6-month follow-up visit, was 80.6% (1099 of 1364 patients). Of 1099 patients who had a favorable outcome at 6 months, 343 (31.2%) were younger than 40 years. Of 1364 patients, 1053 (77.2%) had moderate facial dysfunction (H-B grade III or IV). No pathological spontaneous fibrillation activity (ie, good electromyography [EMG] results) was detected on EMG in 937 of 1364 patients (68.7%), 492 (36.1%) had controlled hypertension, and 673 (49.3%) were treated with oral corticosteroids alone. Multivariable analysis revealed that the following factors were associated with favorable outcome: age younger than 40 years (odds ratio [OR], 1.56; 95% CI, 1.09-2.22), an initial H-B grade of III or IV (OR, 2.62; 95% CI, 1.93-3.57), good EMG results after 2 weeks of treatment (OR, 3.38; 95% CI, 2.48-4.61), absence of diabetes (OR, 1.43; 95% CI, 1.04-2.36), and control of hypertension (OR, 1.64; 95% CI, 1.16-2.33). Multiple logistic regression analysis in this study suggests that multiple clinical factors are associated with favorable outcomes in patients with Bell palsy.

The Effects of folic acid and topiramate on peripheral nerve regeneration

ABSTRACTPeripheral nerve injury creates unusual sensitivity and pathological spontaneous activity in neurons that are described as ectopic discharge. Voltage dependent Na channels are responsible for ectopic discharge. Topiramate (TOP) inhibits voltage-gated sodium channels by blocking both the amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate receptor and folic acid (FA) activity in neurotransmitter synthesis reactions. FA and TOP are anti-apoptotic agents by both phosphorylated-Akt (p-Akt) signaling activation and anti-inflammatory effects at the injury site. We investigated the effects of FA and TOP in peripheral nerve injury. We used rats with a sciatic nerve injury (SNI) treated with FA or TOP once daily for 6 weeks. Histological and electrophysiological tests were used to evaluate the morphology, and motor and sensory functions. Numbers of axons, myelin sheath thickness and axon area were measured using stereological techniques; functionality also was evaluated. Although FA exhibited a positive effect on regeneration by increasing the number of axons, we found no difference in axonal outgrowth or myelin sheath formation between the TOP and FA groups.

Phosphorus content of muscle tissue and muscle function in dairy cows fed a phosphorus-deficient diet during the transition period

Phosphorus (P) deficiency and hypophosphatemia are believed to be associated with muscle function disturbances in dairy cows, particularly around parturition. The objective of this study was to determine the effect of dietary P deprivation during late gestation and early lactation on muscle P homeostasis and muscle function in periparturient dairy cows. Thirty-six multiparous dairy cows in late gestation were randomly assigned either to undergo dietary P depletion or to be offered a diet with adequate P content from 4 wk before to 4 wk after parturition. Phosphorus-deficient rations for dry and lactating cows contained 0.15 and 0.20% P on a dry matter basis, respectively. Blood and muscle tissue for biopsy were obtained and electromyographic examinations were conducted on biceps femoris and intercostal muscles in regular intervals throughout the study. Muscle tissue was analyzed for the total P, adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, creatine phosphate, and tissue water content. Dietary P deprivation resulted in a pronounced and sustained decline of the plasma phosphate concentration, reaching a nadir at calving with mean values below 1.5 mg/dL and remaining below 2.0 mg/dL during the first 4 wk of lactation. Hypophosphatemia was not associated with signs of clinically apparent muscle weakness or disturbed muscle function and was not associated with a decline in the content of any of the studied P-containing compounds in muscle tissue. Accordingly, no association between plasma phosphate concentration and muscle tissue P content was found. Electromyographic examination identified subclinical effects on motor unit action potentials that are indicative of disturbed neuromuscular functionality. Increasing occurrence of pathologic spontaneous activity possibly resulting from membrane instability of nerve or muscle cells and suggestive of myopathy was also recorded as P deprivation progressed. These effects were predominantly observed in intercostal and to a lesser degree biceps femoris muscles. Electromyographic parameters affected by P deprivation were found to be associated primarily with the plasma phosphate and to a lesser extent with the amounts of energy storing P-containing compounds contained in muscle tissue. These results indicate that prolonged and pronounced dietary P deprivation in transition dairy cows leads to marked sustained hypophosphatemia without altering the muscle tissue P homeostasis or causing clinically apparent muscle function disturbances.

Asymmetric recurrent laryngeal nerve conduction velocities and dorsal cricoarytenoid muscle electromyographic characteristics in clinically normal horses

The dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse’s respiratory system: as the sole abductors of the airways, they maintain the size of the rima glottis which is essential for enabling maximal air intake during intense exercise. Dysfunction of the DCA muscle leads to arytenoid collapse during exercise, resulting in poor performance. An electrodiagnostic study including electromyography of the dorsal cricoarytenoid muscles and conduction velocity testing of the innervating recurrent laryngeal nerves (RLn) was conducted in horses with normal laryngeal function. We detected reduced nerve conduction velocity of the left RLn, compared to the right, and pathologic spontaneous activity (PSA) of myoelectrical activity within the left DCA muscle in half of this horse population and the horses with the slowest nerve conduction velocities. The findings in this group of horses are consistent with left sided demyelination and axonal loss, consistent with Recurrent Laryngeal Neuropathy (RLN), a highly prevalent degenerative disorder of the RLn in horses that predominantly affects the left side. The detection of electromyographic changes compatible with RLN in clinically unaffected horses is consistent with previous studies that identified “subclinical” subjects, presenting normal laryngeal function despite neuropathologic changes within nerve and muscle confirmed histologically.

Associations between apparent diffusion coefficient and electromyography parameters in myositis-A preliminary study.

Objective MRI is widely used in several muscle disorders. Diffusion‐weighted imaging (DWI) is an emergent imaging modality sensitive to microstructural alterations in tissue. The apparent diffusion coefficient (ADC) is used to quantify the random motion of water molecules. Electromyography (EMG) is a clinically used diagnostic tool in myositis. The aim of this study was to elucidate possible associations between ADC values and EMG findings in myositis patients.MethodSeven patients (eight investigated muscles) with myositis (mean age 51.43 ± 19 years) were included in this study. The diagnosis was confirmed by histopathology in every case. DWI was obtained with a 1.5‐T scanner using two b‐values 0 and 1000 s/mm². In all patients, a needle electromyography (EMG) was performed within 3 days to the MRI. The following EMG parameters were studied: motor unit action potential (MUAP) amplitudes and durations, as well as pathological spontaneous activity. Spearman's correlation coefficient was used to analyze associations between investigated parameters.ResultsThe estimated mean ADC mean value was 1.51 ± 0.29 × 10−3 mm²/s, mean ADC min was 1.28 ± 0.27 × 10−3 mm²/s, and mean ADC max was 1.73 ± 0.28 × 10−3 mm²/s. Correlation analysis identified significant associations between ADC mean and duration of the MUAP (p = .78 P = .0279) and between ADC min and duration of the MUAP (p = .85, P = .01). There were no significant differences according to pathological spontaneous activity.Conclusion ADC mean and ADC min showed strong positive correlations with the duration of the MUAP in myositis patients. Both modalities might similarly reflect muscle fiber loss in myositis patients.

Quantitative facial electromyography monitoring after hypoglossal-facial jump nerve suture.

Objectives/HypothesisThe time course of the reinnervation of the paralyzed face after hypoglossal‐facial jump nerve suture using electromyography (EMG) was assessed. The relation to the clinical outcome was analyzed.Study DesignRetrospective single‐center cohort studyMethodsReestablishment of motor units was studied by quantitative EMG and motor unit potential (MUP) analysis in 11 patients after hypoglossal‐facial jump nerve suture. Functional recovery was evaluated using the Stennert index (0 = normal; 10 = maximal palsy).ResultsClinically, first movements were seen between 6 and >10 months after surgery in individual patients. Maximal improvement was achieved at 18 months. The Stennert index decreased from 7.9 ± 2.0 preoperatively to a final postoperative score of 5.8 ± 2.4. EMG monitoring performed for 2.8 to 60 months after surgery revealed that pathological spontaneous activity disappeared within 2 weeks. MUPs were first recorded after the 2nd month and present in all 11 patients 8–10 months post‐surgery. Polyphasic regeneration potentials first appeared at 4–10 months post‐surgery. The MUP amplitudes increased between the 3rd and 15th months after surgery to values of control muscles. The MUP duration was significantly increased above normal values between the 3rd and 24th months after surgery.ConclusionReinnervation can be detected at least 2 months earlier by EMG than by clinical evaluation. Changes should be followed for at least 18 months to assess outcome. EMG changes reflected the remodeling of motor units due to axonal regeneration and collateral sprouting by hypoglossal nerve fibers into the reinnervated facial muscle fibers.Level of Evidence3b.

Blockade of pathological retinal ganglion cell hyperactivity improves optogenetically evoked light responses in rd1 mice.

Retinitis pigmentosa (RP) is a progressive retinal dystrophy that causes visual impairment and eventual blindness. Retinal prostheses are the best currently available vision-restoring treatment for RP, but only restore crude vision. One possible contributing factor to the poor quality of vision achieved with prosthetic devices is the pathological retinal ganglion cell (RGC) hyperactivity that occurs in photoreceptor dystrophic disorders. Gap junction blockade with meclofenamic acid (MFA) was recently shown to diminish RGC hyperactivity and improve the signal-to-noise ratio (SNR) of RGC responses to light flashes and electrical stimulation in the rd10 mouse model of RP. We sought to extend these results to spatiotemporally patterned optogenetic stimulation in the faster-degenerating rd1 model and compare the effectiveness of a number of drugs known to disrupt rd1 hyperactivity. We crossed rd1 mice with a transgenic mouse line expressing the light-sensitive cation channel channelrhodopsin2 (ChR2) in RGCs, allowing them to be stimulated directly using high-intensity blue light. We used 60-channel ITO multielectrode arrays to record ChR2-mediated RGC responses from wholemount, ex-vivo retinas to full-field and patterned stimuli before and after application of MFA, 18-β-glycyrrhetinic acid (18BGA, another gap junction blocker) or flupirtine (Flu, a Kv7 potassium channel opener). All three drugs decreased spontaneous RGC firing, but 18BGA and Flu also decreased the sensitivity of RGCs to optogenetic stimulation. Nevertheless, all three drugs improved the SNR of ChR2-mediated responses. MFA also made it easier to discern motion direction of a moving bar from RGC population responses. Our results support the hypothesis that reduction of pathological RGC spontaneous activity characteristic in retinal degenerative disorders may improve the quality of visual responses in retinal prostheses and they provide insights into how best to achieve this for optogenetic prostheses.

Long-term outcome of accessory nerve to suprascapular nerve transfer in obstetric brachial plexus lesion: functional, morphological, and electrophysiological results.

An accessory to suprascapular nerve (XIN-SSN) transfer is considered in patients with obstetric brachial plexus lesion who fail to recover active shoulder external rotation. The aim of this study was to evaluate the quality of extraplexal suprascapular nerve neurotization and to perform a detailed analysis of the infraspinatus muscle (IM) and shoulder external rotation. A XIN-SSN transfer was performed in 14 patients between 2000 and 2007. Patients had been operated at the age of 3.7 ± 2.8 years. Follow-up examinations were conducted up to 8.5 ± 2.5 years. Magnetic resonance imaging was performed to investigate muscle trophism. Fatty muscle degeneration of the IM was classified according to the Goutallier classification. We conducted nerve conduction velocity studies of the suprascapular nerve and needle electromyography of the IM to assess pathologic spontaneous activity and interference patterns. Active glenohumeral shoulder external rotation and global shoulder function were evaluated using the Mallet score. Postoperatively, growth of the IM increased equally on the affected and unaffected sides, although significant differences of muscle thickness persisted over time. There was only grade 1 or 2 fatty degeneration pre- and postoperatively. Electromyography of the IM revealed a full interference pattern in all except one patient, and there was no pathological spontaneous activity. Glenohumeral external rotation as well as global shoulder function increased significantly. Our results indicate that the anastomosis after XIN-SSN transfer is functional and that successful reinnervation of the infraspinatus muscle may enable true glenohumeral active external rotation.

The effect of transient, moderate dietary phosphorus deprivation on phosphorus metabolism, muscle content of different phosphorus-containing compounds, and muscle function in dairy cows

Hypophosphatemia is a common finding in periparturient and anorectic cattle. Although the clinical relevance of hypophosphatemia in cattle is uncertain, it has been empirically associated with persistent recumbency, specifically in periparturient dairy cows. The objective of the present study was to determine if transient dietary phosphorus (P) deprivation over a course of 5 wk, by feeding an approximately 40% P-deficient ration to lactating dairy cows, would result in altered muscle function or muscle P metabolism severe enough to present a risk for animal health and well-being. In addition, we wanted to determine the association between the plasma phosphate concentration ([Pi]) and muscle tissue P content to assess to what extent intracellular P deprivation of muscle cells could be extrapolated from subnormal plasma [Pi]. Ten healthy multiparous, mid-lactating dairy cows received a ration with a P content of 0.18% over a period of 5 wk. Following the P-deprivation phase, the same ration supplemented with P to obtain a dietary P content of 0.43% was fed for 2 wk. Blood and urine samples were collected regularly and muscle biopsies were obtained repeatedly to determine the P content in muscle tissue. Function of skeletal and heart muscles was evaluated by electrocardiography and electromyography conducted repeatedly throughout the study. Feeding the P-deficient ration resulted in the rapid development of marked hypophosphatemia. The lowest plasma [Pi] were measured after 9 d of P depletion and were, on average, 60% below predepletion values. Plasma [Pi] increased thereafter, despite ongoing dietary P depletion. None of the animals developed clinical signs commonly associated with hypophosphatemia or any other health issues. Urine analysis revealed increasing renal calcium, pyridinoline, and hydroxypyridinoline excretion with ongoing P deprivation. Biochemical muscle tissue analysis showed that dietary P depletion and hypophosphatemia were not associated with a decline in muscle tissue P content. Electromyographic examination revealed increased occurrence of pathological spontaneous activity in striated muscles after 2 wk of dietary P depletion in several cows, which could be suggestive of neuromuscular membrane instability. No effect on heart muscle activity was identified electrocardiographically. These results suggest that counter-regulatory mechanisms were sufficient to maintain normal muscle tissue P content during transient and moderate P deprivation. Muscle function was not grossly affected, although the increased occurrence of pathological spontaneous activity suggests that subclinical neuropathy or myopathy, or both, may have occurred with ongoing P deprivation. The results presented here indicate that plasma [Pi] is unsuitable for assessing muscle tissue P content in cattle.

The significance of pathological spontaneous activity in various myopathies

ObjectivePathological spontaneous activity (PSA) in electromyography (EMG) has not yet been systematically analysed in various types of myopathies. Methods136 Patients with well-defined myopathies were retrospectively analysed for the presence of PSA in distal, proximal, and paravertebral muscles. PSA comprised fibrillations (fib)/positive sharp waves (PSW) and high frequency discharges (HFD; i.e., myotonic and complex repetitive discharges). Resultsfib/PSW occurred more frequently than HFD. HFD were rarely myotonic in nature. 50% and more patients presented with HFD in PROMM (80%), Pompe’s disease (70%), matrin-3 myopathy (60%), sIBM (50%), CNM (50%), while far less than 50% of the patients showed RD in LGMD2I (21%), LGMD2A (17%), LGMD2B (17%), LGMD2L (14%), FSHD (4%), BMD (0%). Four different HFD patterns were proposed. ConclusionThe segregation of myopathies relative to the occurrence of PSA and especially HFD in a high prevalence group and in a low prevalence group may be diagnostically valuable. SignificanceThe screening for HFD by means of EMG is also valuable in the diagnosis of non-myotonic myopathies.