Influence of treatment on the maturation of the somesthetic pathway in infants with primary congenital hypothyroidism during the first year of life.

To assess the influence of treatment on the development of the somesthetic pathway in infants with congenital hypothyroidism receiving early treatment, median nerve somatosensory evoked potentials were measured during the 1st y of life. Twenty-nine infants were studied with six to seven somatosensory evoked potential tests per infant. The cervical latency (N13) divided by arm length and the first (N19) and second (N32) cephalic latencies as well as N13-N32 latency were measured. At diagnosis, all components showed a small but significant delay, which was not related to thyroxine (T4) levels before treatment. During treatment, T4 ranged from 50 to 290 nmol/L. At 12 mo, the cervical latency divided by arm length had normalized, whereas N19 and N13-N32 were more abnormal than at diagnosis. For N19, these abnormalities were related to a slow initial rise of T4 (< or = 100 nmol/L after 1 wk of treatment) and the initial N19 values. Abnormal N13-N32 values were associated with high T4 values during treatment (> 200 nmol/L) and the type of congenital hypothyroidism (partial or total deficiency in T4 production). Induction of therapy with l-triiodothyronine rather than l-thyroxine and the occurrence of low T4 values (< 100 nmol/L) after the 4th wk of therapy had no such effect. Our data suggest that, for normal CNS development, euthyroidism should be reached as soon as possible by adequate induction therapy. Thereafter, T4 supplementation should be strictly dosed, keeping the serum T4 values within narrow limits around the mean normal for age, because overtreatment, like initial undertreatment, may lead to CNS abnormalities at the end of the first year.

Somatosensory evoked potentials in neonates with primary congenital hypothyroidism during the first week of therapy.

At the present, the influence of intrauterine hypothyroidism on the fetus is estimated by bone age (BA). BA is also used as a predictor of later neuropsychologic development. The aim of this study was to investigate whether the neurophysiologic maturation of neonates with congenital hypothyroidism (CHT) is delayed at the start of therapy and, if so, whether this delay is comparable to that in BA. Twenty-seven infants with CHT were examined with median nerve somatosensory evoked potentials (SEP) before or within 1 wk after initiation of therapy. The effect of neonatal jaundice, a potential confounder of neonatal SEP, was also evaluated. Cervical (N13), first cephalic (N19), and second cephalic (N32) peak latencies were measured, as well as N13-N19 interval (central conduction time) and N13 latency divided by arm length. The SEP data of 103 normal infants were used as reference values. In the CHT newborns, a maturational delay was found for all SEP parameters. Preterm infants (n = 3) were conspicuously less affected than term patients. In term CHT infants, jaundice during the first postnatal week, but not late jaundice, had an additional adverse effect. SEP delay was not related to initial or actual T4 levels. BA delay exceeded SEP delay by several weeks. Our data suggest that the depressed T4 levels of the hypothyroid fetus and neonate affect the nervous tissue to a lesser degree than bone tissue and, further, that SEP is superior to BA as parameter for the evaluation of neurologic maturation of infants with CHT.

Somatosensory evoked potentials in term and preterm infants in relation to postconceptional age and birth weight.

The effect of age on the maturation of median nerve somatosensory evoked potentials (SEPs) was studied in 103 normal neonates (24 preterm, 79 term) at the postconceptional age (PCA) of 36-48 weeks. The influence of birth weight was evaluated in 44 term neonates, aged 0-7 days, according to their gestational age (GA) stratified into three groups: A: 38-39 weeks (n = 15); B: 39.5-40.5 weeks (n = 15); C: 41-43 weeks (n = 14). The mean birth weight was not different in the three groups. For all infants the N13 latency recorded at cervical (CS2-Fz) level as well as the N19 onset and peak latency at cortical (C3'/C4'-Fz) level were measured. For these parameters and for the N13 latency divided by arm length (N13/AL) and the N19 ascending time (N19AT) the P50, P97 and P3 were calculated as a function of PCA. They were all decreasing in the 36-48 weeks period, fast before 40 weeks and slowly thereafter. The SEP values of groups, A, B and C were not different, but in each group the wave pattern of the cortical SEPs was more mature in the larger than in the smaller infants. For the groups A, B and C together birth weight (in SDS) correlated inversely with the N13/AL and the N19AT (both in SDS) (r = 0.73 and 0.52 respectively, p less than 0.001). Our data indicate that the progression of maturation of the various SEP components in the period of 36-48 PCA is non-linear.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatosensory evoked potentials in neonatal jaundice.

Somatosensory evoked potentials (SEPs) were studied in jaundiced and normal neonates on the day the highest bilirubin values were reached, 2-3 days later, and at five weeks. During the first week three groups were formed according to peak bilirubin values: A: greater than or equal to 250 mumol/l (n = 20), B: 125-250 mumol/l (n = 6), C: less than 125 mumol/l or no jaundice (n = 19). At five weeks 10 infants of group A were reinvestigated, together with 17 controls. Cervical (N13) and scalp SEPs (N19) were recorded with a variable number of stimuli. The SEPs of group B and C did not differ from each other. In group A the N13 peak latencies were within the range of group C at the first investigation, but prolonged at the second and third. The cortical components were prolonged at the first investigation, improved but still prolonged at the second, while the N19 peak latency was still prolonged at the third investigation. The central conduction time (CCT) correlated positively with the bilirubin level. Since a rapid decrease in the N19 amplitude was found for all groups from 25 to 100 stimuli, recordings should be done with a low number of stimuli (less than 100). Our findings indicate that both the periferal and the central components of the SEPs in the neonatal period are delayed by jaundice and that full recovery is not obtained at five weeks. The non-invasive SEP technique can be used as a daily monitor of the effect of bilirubin on the CNS.

The somatosensory evoked potentials of normal infants: influence of filter bandpass, arousal state and number of stimuli.

Median nerve somatosensory evoked potentials (SEPs) were investigated in 35 normal newborns aged 0-5 days. During stimulation at a regular frequency of 0.5/s, potentials deriving from cervical (CS2-Fz) or scalp (C3'-Fz) level were recorded with five different bandpasses (1-100 to 100-5,000 Hz (-6 dB/oct], with a variable number of stimuli (25-350) and in different arousal states: awake or in irregular sleep (non-quiet), or in regular sleep (quiet). The 1-100 Hz filter introduced a slight distorsion of the N13 and N19 (1) and (2) potentials but a better signal-to-noise ratio compared with the other filter settings. A 20-5,000 Hz bandpass resulted in an inacceptable distorsion of the N19 (1) and (2) peak. For the 100-5,000 Hz bandpass an almost complete suppression of the cortical components was obtained. With a 1-100 Hz bandpass a N13 and a N19 potential could be recorded in all infants; in 75% of them a bilobed N19 peak was present. In the quiet state (n = 13) either a bilobed N19 peak was observed with prolonged N19 (1) and (2) peak latencies compared with the non-quiet state or a large unilobed N19 wave. An increase in the number of stimuli from 25 to 100 resulted in a decrease of 33% in the amplitude of the N19(1) peak. We advocate to record SEPs in the neonatal period with a filter bandpass of 1-100 Hz and with a low number of stimuli (25-50), with attention for the arousal state of the infant.

Muscle weakness and congenital contractures in a case of congenital myasthenia.

A case of nonautoimmune, prenatal-onset, congenital myasthenia with congenital contractures including camptodactyly is presented. The clinical features re identical to those in three previously reported cases. In this form of congenital myasthenia, the muscle weakness and congenital contractures may resolve completely after conservative treatment, including anticholinesterase medication. Diagnosis can be made by the characteristic clinical history, neurological assessment, and electromyography with repetitive nerve stimulation.

Distal amyotrophy of predominantly the upper limbs with pyramidal features in a large kinship.

An autosomal dominant disease characterised by amyotrophy of predominantly distal upper limb muscles and mild pyramidal features is described. There are sensory changes in older patients, whilst in others the disease presents itself as a disorder of motor neurons. Owing to variations in the clinical picture, it may be difficult to distinguish this disease in individual patients from distal spinal muscular atrophy, or from pure pyramidal syndromes. There is an overlap in clinical signs between this disease and peroneal muscular atrophy with pyramidal features. Whether or not the latter two conditions are genetically distinct, is a matter of doubt.

Inflammatory myopathy in scapulo-ilio-peroneal atrophy with cardiopathy. A study of two families.

A syndrome of slowly progressive muscle weakness with scapulo-ilio-peroneal distribution and cardiopathy was identified in 26 members of two families. Inheritance was autosomal dominant. Onset of the disease was between 17 and 42 years. Cardiopathy did not antedate skeletal muscle disease and patients had no symptoms of cardiopathy until a late phase of the disease. Initial ECG changes were non-specific, disturbances of conduction and impulse formation developed subsequently. Skeletal muscle biopsies showed neurogenic and myopathic changes with inflammatory cell reaction and perivascular cuffing. The combination of myopathy with neurogenic-like changes is characteristic of many cases of SPA. The inflammatory cell reaction is considered as part of a secondary polymyositis which is at leart partly responsible for muscle pathology.