Wartenberg’s migrant sensory neuritis: a prospective follow-up study

Migrant sensory neuropathy (Wartenberg’s migrant sensory neuritis) is characterized by sudden numbness in the distribution of one or multiple cutaneous nerves. To study disease course and outcome, we prospectively followed 12 patients who presented to our tertiary referral neuromuscular outpatient clinic between January 2003 and January 2004. Medical history, neurological, laboratory and electrophysiological examinations were obtained from all patients. All patients were reviewed a second time in 2007, and five had a follow-up electrophysiological examination. At the first visit, 50% described an episode of stretching preceding the sensory complaints. All but three described pain in the affected area before or concomitant with sensory loss. At clinical examination a median of six skin areas were affected, and in 75% this could be confirmed by nerve conduction studies in at least one nerve. Forty-two percent had involvement of the trigeminal nerve. After a mean disease duration of 7.5 years, three patients reported a complete disappearance of sensory complaints and five that the pain had disappeared, but numbness remained. Three patients still had both painful and numb sensory deficits. One patient developed a distal symmetric sensory polyneuropathy. In conclusion, Wartenberg’s sensory neuritis is a distinct, exclusively sensory, neuropathy, marked by pain preceding numbness in affected nerves. An episode of stretching preceding pain is not necessary for the diagnosis. Wartenberg’s sensory neuritis often retains its spotty, exclusively sensory characteristics after long term follow-up

Motor Unit Integrity in Multifocal Motor Neuropathy: A Systematic Evaluation with CMAP Scans

Introduction/Aims: Progressive axonal loss in multifocal motor neuropathy (MMN) is often assessed with nerve conduction studies (NCS), by recording maximum compound muscle action potentials (CMAPs). However, reinnervation maintains the CMAP amplitude until a significant portion of the motor unit (MU) pool is lost. Therefore, we performed more informative CMAP scans to study MU characteristics in a large cohort of patients with MMN. Methods: We derived the maximum CMAP amplitude (CMAP max), an MU number estimate (MUNE), and the largest MU amplitude stimulus current required to elicit 5%, 50%, and 95% of CMAP max (S5, S50, S95) and relative ranges ([S95 − S5] × 100 / S50) from the scans. These metrics were compared with clinical, laboratory, and NCS results. Results: Forty MMN patients and 24 healthy controls were included in the study. CMAP max and MUNE were reduced in MMN patients (both P <.001). Largest MU amplitude as a percentage of CMAP max was increased in MMN patients (P <.001). Disease duration and treatment duration were not associated with MUNE. Relative range was larger in patients with anti-GM1 antibodies than in those without anti-GM1 antibodies (P =.016) and controls (P <.001). The largest MU amplitudes were larger in patients without anti-GM1 antibodies than in patients with anti-GM1 antibodies (P =.037) and controls (P =.044). Discussion: We found that MU loss is common in MMN and accompanied by enlarged MUs. Presence of anti-GM1 antibodies was associated with increased relative range of MU thresholds and reduction in largest MU amplitude. Our findings indicate that CMAP scans complement routine NCS, and may have potential for practical monitoring of treatment efficacy and disease progression

Long-Term Transplantation Outcomes in Patients With Primary Hyperoxaluria Type 1 Included in the European Hyperoxaluria Consortium (OxalEurope) Registry

INTRODUCTION: In primary hyperoxaluria type 1 (PH1), oxalate overproduction frequently causes kidney stones, nephrocalcinosis, and kidney failure. As PH1 is caused by a congenital liver enzyme defect, combined liver–kidney transplantation (CLKT) has been recommended in patients with kidney failure. Nevertheless, systematic analyses on long-term transplantation outcomes are scarce. The merits of a sequential over combined procedure regarding kidney graft survival remain unclear as is the place of isolated kidney transplantation (KT) for patients with vitamin B6-responsive genotypes. METHODS: We used the OxalEurope registry for retrospective analyses of patients with PH1 who underwent transplantation. Analyses of crude Kaplan–Meier survival curves and adjusted relative hazards from the Cox proportional hazards model were performed. RESULTS: A total of 267 patients with PH1 underwent transplantation between 1978 and 2019. Data of 244 patients (159 CLKTs, 48 isolated KTs, 37 sequential liver–KTs [SLKTs]) were eligible for comparative analyses. Comparing CLKTs with isolated KTs, adjusted mortality was similar in patients with B6-unresponsive genotypes but lower after isolated KT in patients with B6-responsive genotypes (adjusted hazard ratio 0.07, 95% CI: 0.01–0.75, P = 0.028). CLKT yielded higher adjusted event-free survival and death-censored kidney graft survival in patients with B6-unresponsive genotypes (P = 0.025, P < 0.001) but not in patients with B6-responsive genotypes (P = 0.145, P = 0.421). Outcomes for 159 combined procedures versus 37 sequential procedures were comparable. There were 12 patients who underwent pre-emptive liver transplantation (PLT) with poor outcomes. CONCLUSION: The CLKT or SLKT remains the preferred transplantation modality in patients with PH1 with B6-unresponsive genotypes, but isolated KT could be an alternative approach in patients with B6-responsive genotypes

Longitudinal prospective cohort study to assess peripheral motor function with extensive electrophysiological techniques in patients with Spinal Muscular Atrophy (SMA): the SMA Motor Map protocol

Background: Hereditary spinal muscular atrophy (SMA) is a motor neuron disorder with a wide range in severity in children and adults. Two therapies that alter splicing of the Survival Motor Neuron 2 (SMN2) gene, i.e. nusinersen and risdiplam, improve motor function in SMA, but treatment effects vary. Experimental studies indicate that motor unit dysfunction encompasses multiple features, including abnormal function of the motor neuron, axon, neuromuscular junction and muscle fibres. The relative contributions of dysfunction of different parts of the motor unit to the clinical phenotype are unknown. Predictive biomarkers for clinical efficacy are currently lacking. The goals of this project are to study the association of electrophysiological abnormalities of the peripheral motor system in relation to 1) SMA clinical phenotypes and 2) treatment response in patients treated with SMN2-splicing modifiers (nusinersen or risdiplam). Methods: We designed an investigator-initiated, monocentre, longitudinal cohort study using electrophysiological techniques (‘the SMA Motor Map’) in Dutch children (≥ 12 years) and adults with SMA types 1–4. The protocol includes the compound muscle action potential scan, nerve excitability testing and repetitive nerve stimulation test, executed unilaterally at the median nerve. Part one cross-sectionally assesses the association of electrophysiological abnormalities in relation to SMA clinical phenotypes in treatment-naïve patients. Part two investigates the predictive value of electrophysiological changes at two-months treatment for a positive clinical motor response after one-year treatment with SMN2-splicing modifiers. We will include 100 patients in each part of the study. Discussion: This study will provide important information on the pathophysiology of the peripheral motor system of treatment-naïve patients with SMA through electrophysiological techniques. More importantly, the longitudinal analysis in patients on SMN2-splicing modifying therapies (i.e. nusinersen and risdiplam) intents to develop non-invasive electrophysiological biomarkers for treatment response in order to improve (individualized) treatment decisions. Trial registration: NL72562.041.20 (registered at https://www.toetsingonline.nl. 26–03-2020)

Determinants of Kidney Failure in Primary Hyperoxaluria Type 1:Findings of the European Hyperoxaluria Consortium

INTRODUCTION: Primary hyperoxaluria type 1 (PH1) has a highly heterogeneous disease course. Apart from the c.508G&gt;A (p.Gly170Arg) AGXT variant, which imparts a relatively favorable outcome, little is known about determinants of kidney failure. Identifying these is crucial for disease management, especially in this era of new therapies. METHODS: In this retrospective study of 932 patients with PH1 included in the OxalEurope registry, we analyzed genotype-phenotype correlations as well as the impact of nephrocalcinosis, urolithiasis, and urinary oxalate and glycolate excretion on the development of kidney failure, using survival and mixed model analyses.RESULTS: The risk of developing kidney failure was the highest for 175 vitamin-B6 unresponsive ("null") homozygotes and lowest for 155 patients with c.508G&gt;A and c.454T&gt;A (p.Phe152Ile) variants, with a median age of onset of kidney failure of 7.8 and 31.8 years, respectively. Fifty patients with c.731T&gt;C (p.Ile244Thr) homozygote variants had better kidney survival than null homozygotes ( P = 0.003). Poor outcomes were found in patients with other potentially vitamin B6-responsive variants. Nephrocalcinosis increased the risk of kidney failure significantly (hazard ratio [HR] 3.17 [2.03-4.94], P &lt; 0.001). Urinary oxalate and glycolate measurements were available in 620 and 579 twenty-four-hour urine collections from 117 and 87 patients, respectively. Urinary oxalate excretion, unlike glycolate, was higher in patients who subsequently developed kidney failure ( P = 0.034). However, the 41% intraindividual variation of urinary oxalate resulted in wide confidence intervals. CONCLUSION: In conclusion, homozygosity for AGXT null variants and nephrocalcinosis were the strongest determinants for kidney failure in PH1. </p

Nerve conduction studies in polyneuropathy: practical physiology and patterns of abnormality

Nerve conduction studies are an essential part of the work-up of peripheral neuropathies. Many neuropathic syndromes can be suspected on clinical grounds, but optimal use of nerve conduction study techniques (in combination with needle electromyography) allows diagnostic classification and is therefore crucial to understanding and separation of neuropathies. Multifocal motor neuropathy, for example, may clinically present as ALS. Detection of evidence of demyelination (conduction blocks) leads to the correct diagnosis and to proper treatment. Nerve conduction studies provide essential information on (1) the spatial pattern of neuropathy, (2) the pattern of abnormalities distinguishing between primarily axonal and demyelinating pathology, and (3) the severity of neuropathic damage. This information is very comprehensive since many nerves and long segments of individual nerves can be sampled. Moreover the information is extremely detailed to the extent that the cellular pathology of a patient's neuropathy is usually defined best by physiological testing rather than by biopsy. Neuropathies can be generalized, focal, or multi-focal; they can be symmetric or asymmetric; they can be distally predominant or proximal and distal. Primarily axonal neuropathies mainly affect sensory nerve and compound muscle action potential amplitudes, whereas demyelinating neuropathies lead to slowing of nerve conductions, and to increased temporal dispersion or conduction block. Usually, the pattern of demyelination allows to distinguish hereditary (uniform demyelination) from acquired (segmental demyelination) neuropathies. Electrodiagnostic criteria for primary demyelination are helpful to identify acquired demyelinating neuropathies

Nerve conduction studies after decompression in painful diabetic polyneuropathy

Purpose: To investigate the influence of nerve decompression at potential entrapment sites in the lower extremity in painful diabetic polyneuropathy on nerve conduction study variables. Methods: Forty-two patients with painful diabetic polyneuropathy were included in this prospective randomized controlled trial. Preoperative nerve conduction studies were performed bilaterally. Each patient underwent unilateral surgical decompression of the tibial nerve and common, superficial, and deep peroneal nerves. The contralateral side was used as a control: within-patient comparison. One year postoperatively, the nerve conduction studies were repeated. Univariate paired sample T-tests and a multivariate analysis of variance were performed to compare data. Results: In univariate analysis of the peroneal nerve, the distal compound muscle action potential amplitude measured at the extensor digitorum brevis muscle of the intervention legs decreased significantly, as did the area drop measured at the extensor digitorum brevis muscle of the control legs. The distal motor latency measured at the extensor digitorum brevis muscle of the intervention legs increased significantly, as did the distal compound muscle action potential amplitude measured at the anterior tibial muscle of the control legs. For the tibial nerve, the distal compound muscle action potential duration decreased significantly in the control legs. The multivariate analysis showed no significance overall. Conclusions: Decompression of nerves of the lower extremity in patients with painful diabetic polyneuropathy has no beneficial effect on nerve conduction study variables 12 months after surgery