Jenny Lin

Stimulated jitter analysis for the evaluation of neuromuscular junction disorders in children

Stimulated jitter analysis (stim‐JA) using a concentric needle electrode is a technique used to study the neuromuscular junction (NMJ) without voluntary activation. Our objective was to study the diagnostic sensitivity, specificity, and feasibility of stim‐JA in infants and children with suspected NMJ defects.

Stimulated jitter analysis in the early diagnosis of infant botulism

continued due to the development of severe acne. Following 8 years of slow progression of upper limb symptoms, he developed diplopia and right-sided ptosis. An edrophonium test showed substantial improvement not only in his eye signs, but also in hand and finger strength. Acetylcholine receptor antibodies were positive (0.64 nmol/L). At that time, 3 HZ repetitive nerve stimulation showed a 31% decrement of the abductor pollicis brevis, which attenuated immediately post-exercise. A thymectomy was performed, and the patient improved with a combination of pyridostigmine and intravenous immunoglobulin. Although rare, several cases of predominantly distal myasthenia gravis have been reported. When distal weakness is the presenting feature, it most often affects finger extensors, but the reason for this underlying selectivity is unknown. As emphasized by Mongiovi et al., NMJ disorders should still be considered when routine EMG shows typical, “myopathic,” features (small, short duration motor unit potentials), even with abnormal spontaneous activity. In this setting, myasthenia gravis is possible even if weakness is predominantly distal. Neurophysiological testing for an NMJ disorder should be considered in all patients who undergo EMG for a suspected myopathy.

Hepatic Pulmonary Fusion: Two Cases with Diaphragmatic Hernia and One Case with Pentalogy of Cantrell

Hepatic pulmonary fusion (HPF) is characterized by a fibrous connection between the liver and lung tissue. We present two cases of hepatic pulmonary fusion diagnosed with right diaphragmatic hernia and a third case with Pentalogy of Cantrell exhibiting complete agenesis of the diaphragm and finger-like projections of liver adhered to the right lung. It has been proposed that this anomaly is secondary to developmental failure of the mesoderm between days 14–18 after conception and is attributed to diaphragmatic maldevelopment. Understanding the molecular-genetic basis of diaphragmatic hernias may shed light on this unusual presentation and explain why other cases show no fusion.

Congenital Diaphragmatic Hernia with Emphasis on Embryology, Subtypes, and Molecular Genetics

Historians, scientists, and researchers have been fascinated by the diaphragm for many centuries. Homer first described Trojan War battle wounds with reference to the diaphragm in the 9th century B.C. From 500-430 B.C., Empedocles of Agrigentum was one of the first people to study the physiology of respiration. In this early period of medical knowledge, however, the purpose of the diaphragm bewildered scientists. Hippocrates observed the diaphragm’s inherent fragility and thinness that caused it to throb at any instance of unexpected joy or sorrow. Plato hypothesized that the diaphragm was not involved with respiration but rather served as a boundary between parts of the soul. It was not until Galen in the 2nd century A.D. that the actions of the diaphragm were described as upward isovolume movements during the period of rib cage expansion in respiration(Skandalakis 2004).

Jitter values in infants

Pitt and Jabre recently described jitter values in infants and very young children using the e-norm method. We retrospectively reviewed all infant electromyograms performed in our laboratory between 2014 and 2016 and included 17 studies (9 boys and 6 girls, mean age 4.4 6 3.2 months) with jitter values obtained using the stimulated jitter technique. A total of 231 apparent single fiber action potentials (ASFAPs) were analyzed. The mean and standard deviation for the mean jitter values were calculated (Table 1). Ten infants with suspected neuromuscular junction (NMJ) disorders and with normal neurological examination and negative genetic/laboratory testing had a mean mean consecutive difference (MCD) of 22.9 6 1.8 ls (range 20–25 ls). Five infants with confirmed NMJ disorders [3 with congenital myasthenic syndrome (CMS) and 2 with infant botulism] had a mean MCD of 59.8 6 19.3 ls (range 42–92 ls). One infant had a mean MCD of 43 ls at the initial visit, but at 6 months follow-up she had a normal neurological examination and laboratory testing, and a mean MCD of 22 ls. In another instance, a 6-week-old infant with suspected CMS had a mean MCD of 26 ls on initial study, but a repeat study performed for persistent symptoms 7 months later showed a mean MCD of 51 ls. She responded to enteral pyridostigmine, and genetic testing confirmed a mutation in the choline acetyltransferase gene (CHAT). Based on our data, we suggest reference ranges for mean jitter values in infants as: normal, 25 ls; borderline, 26–44 ls; and abnormal,> 45 ls. In our experience, the majority of healthy infants with a normal neurological examination and negative laboratory work-up had mean jitter values 25 ls. However, infants with borderline mean jitter values (26–44 ls) should have close clinical follow-up, ancillary laboratory testing, and repeat jitter analysis study to prevent underor over-diagnosis of NMJ disorders.

The Spectrum of Pulmonary Malformation in Trisomy-21 Patient. A Review with Emphasis on the Molecular-Genetic Basis

Gene overexpression has been identified as a primary determining factor for the distinct Down syndrome (DS) phenotypes. Previous genetic research has identified a spectrum of gene expressions responsible for many of the observed traits in DS patients including cardiovascular, brain, and GI anomalies. However, the molecular/genetic basis underlying pulmonary anomalies are yet to be identified, even though respiratory complications represent the leading cause of morbidity and mortality in DS patients. In this article, we will discuss the Etiopathogenesis and spectrum of pulmonary anomalies in DS patients.

Quantitative electromyography in ambulatory boys with Duchenne muscular dystrophy

This studys objective was to evaluate quantitative electromyography (QEMG) using multiple‐motor‐unit (multi‐MUP) analysis in Duchenne muscular dystrophy (DMD).

Electrodiagnostic Abnormalities in Tick Paralysis: A Case Report and Review of Literature.

Objective: To study the electrodiagnostic abnormalities in tick paralysis. Methods: A 7-year-old girl with acute onset proximal muscle weakness and an engorged dog tick attached to her scalp was evaluated. Results: The routine motor nerve conduction study showed normal compound muscle action potential amplitude. The stimulated jitter analysis of the orbicularis oculi muscle showed normal jitter with no blocking. The quantitative electromyography of the proximal muscles showed decreased mean duration of the motor unit potentials. Conclusion: We propose toxin-mediated direct skeletal muscle involvement as one of the reasons for muscle weakness in tick paralysis.

Malignant Renal Tumors

The majority of pediatric renal tumors are Wilms’ tumors. Of particular concern are those renal neoplasms carrying malignant potential. These entities are given particular attention in this chapter. Universally, partial and radical nephrectomies are used to treat both benign and malignant neoplasms. Chemotherapies have improved the prognosis of many malignant renal tumors, such as Wilms, but others, especially those carrying INI-1 mutations, remain difficult to treat and have high mortality rates. More molecular and genetic research is needed to fully understand and successfully treat this subset of childhood tumor.

Reply: To PMID 25787697.

1. Verma S, Lin J, Barkhaus PE. Stimulated jitter analysis in the early diagnosis of infant botulism. Muscle Nerve (to appear). 2. Kouyoumdjian JA, Stålberg EV. Concentric needle jitter on stimulated orbicularis oculi in 50 healthy subjects. Clin Neurophysiol 2011; 122:617–622. 3. Churchill-Davidson HC, Wise RP. Neuromuscular transmission in the newborn infant. Anesthesiology 1963;24:271–278. 4. Koenigsberger MR, Patten B, Lovelace RE. Studies of neuromuscular function in the newborn: 1. A comparison of myoneural function in the full term and premature infant. Neuropaediatrie 1973;4:350–361. 5. Chaudhry V, Crawford TO. Stimulation single-fiber EMG in infant botulism. Muscle Nerve 1999;22:1698–1703. 6. Stålberg EV, Sanders DB. Jitter recordings with concentric needle electrodes. Muscle Nerve 2009;40:331–339. 7. Sanders DB. Measuring jitter with concentric needle electrodes. Muscle Nerve 2013;47:317–318.