Expanding the spectrum of LAMB2: Pierson syndrome associated with neuromuscular junction disorder in two patients.

LAMB2 gene disorders present with different phenotypes. Pierson syndrome (PS) is a common phenotype associated with LAMB2 variants. Neuromuscular phenotype has been reported including hypotonia and developmental delay. However, neuromuscular junction abnormalities represented as congenital myasthenic syndrome (CMS) was reported in one adult patient only. Here, in this paper, we present two pediatric cases with a severe presentation of PS and have CMS so expanding the knowledge of LAMB2 related phenotypes. The first patient had hypotonia and global developmental delay. Targeted genetic testing panel demonstrated homozygous pathogenic variant in the LAMB2 gene (c.5182C>T, pGln1728*) which was reported by Maselli et al. 2009. Repetitive nerve stimulation (RNS) showed a decremental response at low frequency of 3 Hz. On the other hand, the second patient had profound weakness since birth. Tri-Whole exome sequencing showed homozygous pathogenic variant in the LAMB2 gene c.2890C>T, pArg964*. A trial of salbutamol did not improve the symptoms. Both patients passed away from sequala of PS. The spectrum of phenotypic changes associated with LAMB2 mutations is still expanding, and further investigation into the various clinical and morphologic presentations associated with these mutations is important to better identify and manage affected individuals.

Pain perception during electrodiagnostic studies and the impact of learners.

INTRODUCTION/AIMS: Electrodiagnostic testing (EDX) may be perceived as painful, which may influence patient expectations and test completion. Our aim was to characterize which component of the EDX was more painful, and to determine if any factors, particularly performance by a learner, influenced this perception. METHODS: Participants were prospectively recruited and completed a brief questionnaire to rate their perception of pain before and after each component of the EDX. Demographic information and information about the test itself was collected. RESULTS: A total of 251 participants were recruited, 55.3% female, with a mean age of 52.9 y. Most participants rated pain after nerve conduction studies (NCS) and needle electromyography (EMG) as mild to moderate with a similar number rating each component as more painful than the other. There was no effect of sex on overall ratings, although females felt that the test was more painful than anticipated more often than males. If a learner performed the EMG, it was more likely that the test would be rated as moderately to severely painful, and more likely for the EMG to be rated as more painful than the NCS (p < .05). DISCUSSION: The finding that NCS and EMG perceived pain were similar may help accurately inform patients of test expectations, guide test planning and help reduce the likelihood of incomplete or canceled testing. More effort might be required to help mitigate EMG pain when learners are involved.