Inhibitory conditioning stimulus in transcranial magnetic stimulation reduces the number of excited spinal motor neurons

OBJECTIVE

To study the mechanisms of amplitude attenuation caused by a transcranial magnetic conditioning stimulus. Both conventional MEPs and the recently described triple stimulation technique (TST) were applied; the latter to improve the quantification of the response size decrease.

METHODS

TST uses a peripheral collision method to eliminate the effects of desynchronization of the transcranial magnetic stimulation (TMS) induced spinal motor neuron discharges. The attenuation of motor evoked potentials (MEPs) and responses to TST was studied in 10 healthy volunteers using the conditioning-test paradigm with 2 ms interstimulus intervals.

RESULTS

Conventional MEPs and responses to TST demonstrated a marked attenuation by the preceding conditioning stimulus in all subjects. The ratio of MEP to TST amplitudes was the same in conditioned and unconditioned responses.

CONCLUSIONS

Our findings suggest that the transcranial conditioning stimulus does not change the degrees of desynchronization of spinal motor neuron discharges, but results in a reduced number of excited alpha motor neurons. This reduction can be estimated by both MEPs and TST.

Obesity after childhood craniopharyngioma--German multicenter study on pre-operative risk factors and quality of life

BACKGROUND

Craniopharyngiomas are tumorous embryogenic malformations. As the survival rate after craniopharyngioma is high (92 %), prognosis and quality of life (QoL) in survivors mainly depend on adverse late effects such as obesity.

PATIENTS AND METHODS

We analyzed 214 children and adolescents with craniopharyngioma. The records of 185 patients (86 %) were available for retrospective analysis of weight profiles and risk factors for obesity. Quality of life (QoL) was measured in 145 patients by the Fertigkeitenskala Münster/Heidelberg score (FMH) and in 77 patients by PEDQOL questionnaire.

RESULTS

Eighty-two of 185 patients (44 %) developed severe obesity (body mass index [BMI] > 3 SD). Obese patients were compared with 79 patients (43 %) who kept normal weight (BMI < 2 SD). No differences between obese and normal weight patients were found in terms of gender distribution, age at diagnosis and follow-up period. However, the BMI SDS at the time of diagnosis was higher (p < 0.0001) in patients who developed obesity than in those who did not. Furthermore, obese patients presented with bigger tumors (p < 0.05) and a higher rate of a hydrocephalus requiring a shunt (p < 0.05) and hypothalamic involvement (p < 0.05). The mothers of patients who developed severe obesity had a higher BMI (p < 0.001) at the time of diagnosis. Obese patients had a higher height-SDS at diagnosis (p < 0.05) and at the time of last follow-up (p < 0.05) when compared with normal weight patients. A prediction model for severe obesity after craniopharyngioma was calculated by logistic regression based on the risk factors: patient's BMI > 2 SD at diagnosis (p < 0.05; odds ratio: 16.4), hypothalamic involvement (p < 0.05; odds ratio: 3.4) and maternal BMI > 25 kg/m(2) (p < 0.05; odds ratio: 4.6). Significant increases in BMI (p < 0.001) occurred during the early post-operative period especially during the first three years after diagnosis. FMH percentiles correlated negatively with BMI SDS (Spearman r: - 0.37; p < 0.001). Children with craniopharyngioma rated their QoL more negative (p < 0.05) in regard to physical abilities, cognitive functioning and social functioning when compared with healthy children of the same age group. Severely obese patients with craniopharyngioma estimated their QoL lower (p < 0.05) for all domains except for autonomy, cognition and familial integration in comparison with non-obese patients.

CONCLUSION

Hypothalamic tumor involvement and familial disposition for obesity are risk factors for the development of severe obesity in patients with craniopharyngioma. As weight gain starts early after diagnosis and severe obesity causes a reduction in QoL, early therapeutic efforts should be considered in patients at risk. To confirm our results the prospective multicenter study Kraniopharyngeom 2000 on children and adolescents with craniopharyngioma was initiated (www.kraniopharyngeom.com).

Neurosurgical interventions in children with Maroteaux-Lamy syndrome. Case report and review of the literature

This paper reports the case of a 14-year-old child with Maroteaux-Lamy syndrome (mucopolysaccharidosis type 6) who was treated consecutively for compressive damage of the optic nerves, hydrocephalus communicans and progressive spastic tetraparesis within 2 years. The clinical course of the patient is presented and the pathophysiologic mechanisms of disease progression in patients with Maroteaux-Lamy syndrome are discussed and reviewed.

Botulinum toxin treatment in cerebral palsy: evidence for a new treatment option

Intramuscular injections of botulinum toxin type A (BTX-A) have increasingly been used to reduce spasticity in specific muscle groups in children with cerebral palsy. Targets of therapeutic efforts are improvement of gross motor function, alleviation of pain or facilitation of hygienic care. Placebo-controlled studies have shown the local and functional effectiveness of BTX-A for the treatment of dynamic pes equinus. Whether long-term treatment with BTX-A improves motor development and delays contractures is still under investigation.

Clinical and experimental results on cardiac troponin expression in Duchenne muscular dystrophy

BACKGROUND

Because of controversial earlier studies, the purpose of this study was to provide novel experimental and additional clinical data regarding the possible reexpression of cardiac troponin T (cTnT) in regenerating skeletal muscle in Duchenne muscular dystrophy (DMD).

METHODS

Plasma from 14 patients (mean age, 7.5 years; range, 5.7-19.4 years) with DMD was investigated for creatine kinase (CK), the CK MB isoenzyme (CKMB), cTnT and cardiac troponin I (cTnI), and myoglobin. cTnT concentrations were measured by an ELISA (second-generation assay; Roche) using the ES 300 Analyzer. cTnI, myoglobin, and CKMB were measured by an ELISA using the ACCESS System (Beckman Diagnostics). Troponin isoform expression was studied by Western blot analysis in remnants of skeletal muscle biopsies of three patients with DMD and in an animal model of DMD (mdx mice; n = 6).

RESULTS

There was no relation of cTnT and cTnI to clinical evidence for cardiac failure. cTnI concentrations remained below the upper reference limit in all patients. cTnT was increased (median, 0.11 microg/L; range, 0.06-0.16 microg/L) in 50% of patients. The only significant correlation was found for CK (median, 3938 U/L; range, 2763-5030 U/L) with age (median, 7.5 years; range, 6.8-10.9 years; r = -0.762; P = 0.042). Western blot analysis of human or mouse homogenized muscle specimens showed no evidence for cardiac TnT and cTnI expression, despite strong signals for skeletal muscle troponin isoforms.

CONCLUSIONS

We found no evidence for cTnT reexpression in human early-stage DMD and in mdx mouse skeletal muscle biopsies. Discrepancies of cTnT and cTnI in plasma samples of DMD patients were found, but neither cTnT nor cTnI plasma concentrations were related with other clinical evidence for cardiac involvement.

Dopa-responsive dystonia: mutation analysis of GCH1 and analysis of therapeutic doses of L-dopa. German Dystonia Study Group

Analysis of the gene GCH1 in 58 patients with dystonia and a positive response to L-dopa revealed mutations in 30 individuals from 22 families. Thirteen of the mutations observed were familial, three occurred de novo, and inheritance could not be determined in six cases. There was no mutation in the promoter region of GCH1 in any patient. The doses of L-dopa given to members of the two groups were not significantly different.

The gene encoding gigaxonin, a new member of the cytoskeletal BTB/kelch repeat family, is mutated in giant axonal neuropathy

Disorganization of the neurofilament network is a prominent feature of several neurodegenerative disorders including amyotrophic lateral sclerosis (ALS), infantile spinal muscular atrophy and axonal Charcot-Marie-Tooth disease. Giant axonal neuropathy (GAN, MIM 256850), a severe, autosomal recessive sensorimotor neuropathy affecting both the peripheral nerves and the central nervous system, is characterized by neurofilament accumulation, leading to segmental distension of the axons. GAN corresponds to a generalized disorganization of the cytoskeletal intermediate filaments (IFs), to which neurofilaments belong, as abnormal aggregation of multiple tissue-specific IFs has been reported: vimentin in endothelial cells, Schwann cells and cultured skin fibroblasts, and glial fibrillary acidic protein (GFAP) in astrocytes. Keratin IFs also seem to be alterated, as most patients present characteristic curly or kinky hairs. We report here identification of the gene GAN, which encodes a novel, ubiquitously expressed protein we have named gigaxonin. We found one frameshift, four nonsense and nine missense mutations in GAN of GAN patients. Gigaxonin is composed of an amino-terminal BTB (for Broad-Complex, Tramtrack and Bric a brac) domain followed by a six kelch repeats, which are predicted to adopt a beta-propeller shape. Distantly related proteins sharing a similar domain organization have various functions associated with the cytoskeleton, predicting that gigaxonin is a novel and distinct cytoskeletal protein that may represent a general pathological target for other neurodegenerative disorders with alterations in the neurofilament network.

CNS lipoma in patients with epidermal nevus syndrome

Epidermal nevus syndrome (ENS) is a congenital neurocutaneous disorder characterized by linear nevus with a significant involvement of the nervous, ophthalmological and skeletal systems. Clinical manifestations of ENS include neurological features such as mental retardation, seizures, and movement disorders which are caused by a wide range of neuropathological lesions. We describe three patients with ENS, all of whom had in addition to the characteristic features of ENS intracranial and/or intraspinal lipomas. In one patient the lipoma extended from the thoracal vertebra 8 to the 4th ventricle; in the second patient it was localized on T9, and in the third patient an intracranial lipoma was located at the right cerebellopontine angle. The intraspinal lipomas caused a significant spastic movement disorder. So far, CNS lipomas have not been described as typical neuropathological findings in ENS. The differential diagnosis to encephalocraniocutaneous lipomatosis with the typical finding of CNS lipoma is discussed.

Nonconvulsive status epilepticus--a possible cause of mental retardation in patients with Lennox-Gastaut syndrome

Lennox-Gastaut syndrome (LGS) is one of the most severe types of childhood epilepsy. It is usually resistant to treatment and associated with mental retardation. To delineate the risk factors associated with the outcome of LGS, we evaluated, in a retrospective and multicentre study, the course of the disease, EEG tracings, and intellectual function in 101 patients. Inclusion criteria were the presence of tonic seizures as well as slow spike and wave complexes in the EEG. The average documented observation period was 16 years (range 4-31 years). Overall, the intellectual and neurological outcome was poor. At the last follow-up, 38% of the patients could not speak, 21% were unable to walk and only 4% were free of seizures. Four independent risk factors for severe mental retardation were identified by multivariate analysis. These were in a decreasing order of importance: nonconvulsive status epilepticus (NCSE), odds ratio (OR) 25.2, a previous diagnosis of West syndrome (OR 11.6), a symptomatic etiology of epilepsy (OR 9.5), and an early age at onset of epilepsy (OR 4.7). The results highlight the association between NCSE and the severity of mental retardation in patients with LGS; this association appears to be independent of symptomatic etiology. Our data provide an indirect evidence that, at least in some of the patients, NCSE is not only a concomitant feature, but also a cause of severe mental retardation.

Evaluation of botulinum toxin A therapy in children with adductor spasm by gross motor function measure

Intramuscular injection of botulinum neurotoxin A is a relatively new method for treating spastic movement disorders in children. One major goal of any therapy for patients with movement disorders is to improve gross motor function. In this study, 18 patients with adductor spasm were treated with botulinum neurotoxin A. Treatment effect was determined with the Gross Motor Function Measure, a standardized, validated instrument designed to assist in assessment of gross motor function. Spastic muscle hyperactivity and joint mobility were evaluated by the modified Ashworth Scale and by range of motion, respectively. Compared to pretreatment values, significant improvement in gross motor function (P < .010), decrease in the modified Ashworth Scale, and increase in the range of motion (P < .010) were achieved. Patients with moderate impairment of gross motor function (classed at level III and level IV in the Gross Motor Function Classification System) benefited most from treatment. In patients with severe handicap (level V), only one of five treated patients showed improvement in gross motor function. Nevertheless, all patients in this subgroup benefited from improved ease in hygienic care. In conclusion, we have demonstrated that for most children with moderate functional impairment, the Gross Motor Function Measure is a useful instrument for objective documentation of improvements of gross motor function following treatment with botulinum neurotoxin A.

Development of the corticospinal system and hand motor function: central conduction times and motor performance tests

Maturation of the corticospinal (CS) tract and hand motor function provide paradigms for central nervous system development. In this study, involving 112 participants (aged from 0.2 to 30 years), we evaluated central motor conduction times (CMCT) obtained with transcranial magnetic stimulation (TMS) during preinnervation conditions of facilitation and relaxation. Auditory reaction time, velocity of a ballistic movement of the arm, finger tapping, diadochokinesis, and fine motor visuomanual tracking were also examined. The maturation profiles for every parameter were calculated. CMCTs for the different preinnervation conditions reached adult values at different times and this could be explained by maturation of excitability at the cortical and spinal level. A stable phase for CMCTs and reaction time was reached during childhood. Parameters which measured motor speed and skill indicated that the development of these continued into adulthood. The maturation of the fast CS tract seems to be completed before the acquisition of the related motor performance has been accomplished. In conclusion, we could demonstrate that data from several neurophysiological methods can be combined and used to study the maturation of the function of the nervous system. This approach could allow appraisal of pathological conditions that show parallels with omissions or lack of developmental progress.

Increased urinary excretion of tubular enzymes and proteins in children with epilepsy

Cross-sectional analysis of children undergoing treatment with anti-epileptic drugs has shown an increased urinary excretion of tubular enzymes and proteins. This has usually been interpreted as a consequence of subclinical renal-tubular damage or enzyme induction. We measured excretion of tubular enzymes and proteins in 29 children who suffered from epileptic seizures and in 27 control children. Investigations were undertaken at diagnosis before the start of treatment and 3-4 months later. At diagnosis we found a slightly, but statistically significant increased excretion of N-acetyl-beta-glucosaminidase and alpha1-microglobulin. There was no significant difference between patients with an idiopathic and symptomatic aetiology of seizures or between patients with different seizure types. At the second investigation, in children treated with carbamazepine or valproate, no further increase occurred. We conclude that the increased excretion of tubular enzymes and proteins in children with epilepsy is most probably not due to a side-effect of the anti-epileptic drugs, but to a physiological alteration associated with the epilepsy itself. While the cause is unknown, the influence of serotonin metabolism is discussed.

Efficacy of lamotrigine and vigabatrin in drug-resistant epilepsies of childhood

It was the purpose of this study to compare the efficacy and side effects of lamotrigine (LTG) and vigabatrin (VGB) as add-on therapy in epilepsies of childhood resistant to conventional drugs. Retrospective analysis of the medical charts and electroencephalograms of 134 children (LTG 57, VGB 77) was performed considering the various epileptic seizures and syndromes. In general, LTG and VGB had similar efficacy, with 30-40 % of patients demonstrating significant improvement. Few differences according to seizure type and epileptic syndrome were observed. Primary generalized tonic-clonic seizures more frequently improved and less frequently worsened with LTG than with VGB. In tonic seizures the treatment results were significantly more favorable with VGB. Only insignificantly better results occurred with LTG in the generalized group and with VGB in the localization-related group. VGB was significantly more effective in symptomatic than in idiopathic and cryptogenic syndromes. The frequency of adverse reactions with both drugs was close to 60%. However, treatment had to be discontinued because of severe rashes in only a few patients taking LTG or because of behavior disturbances in patients taking VGB.

Chronic inflammatory demyelinating polyradiculoneuropathy in children and their response to treatment

PURPOSE OF THE STUDY

To collect data on both the natural history of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) in children and their response to treatment.

STUDY DESIGN

Retrospective multicentre study, using standardised criteria for the evaluation of hospital records and semi-quantitative scoring of disability.

RESULTS

A total of 21 patients (age range 2-14 years) were observed clinically over a median period of four years. At the peak of the disease, 12 children were unable to walk. None of the patients required artificial ventilation. Most of the children were treated with corticosteroids or high-dosage immunoglobulins (2 g/kg body weight), or both. Nine experienced spontaneous as well as treatment-related remissions and relapses; in twelve the degree of disability changed exclusively parallel to modifications of the treatment. Corticosteroids were used as the first-line drug for 11 patients and were effective for eight; prolonged treatment (up to 2 years) was usually necessary. Administration of high-dosage intravenous immunoglobulins was used for 14 children, resulting in significant and rapid clinical improvement in 12. In eight patients the treatment with immunoglobulins had to be repeated at regular intervals for up to four years. At the last follow-up visit, 12/21 patients were off treatment for 3 months to 11 years, showing none or only slight symptoms and signs; of those still receiving treatment three were in a stable condition, five exhibited significant fluctuation of symptoms, and one was unable to walk unaided.

CONCLUSION

In the majority of children with CIDP, the protracted and debilitating course of the disease can be alleviated by treatment with either corticosteroids or immunoglobulins. For patients resistant to this treatment an escalating regimen with plasmapheresis, immunosuppressive drugs or interferon-alpha should be considered.

Absence of transcallosal inhibition in adolescents with diplegic cerebral palsy

The role of intracortical organization in the pathophysiology of cerebral palsy (CP) is not clear. We used transcranial magnetic stimulation to investigate the paradigm of transcallosal inhibition (TI) in a group of adolescent patients with diplegic CP (n = 4), hereditary spastic paraplegia (n = 2), and healthy control adolescents (n = 4). None of the patients with CP showed TI, whereas all other subjects had normal TI. These findings indicate a lack of inhibitory control of the motor cortex in CP.

Fetal cerebral AV-malformation and cardiomegaly, diagnostic and therapeutic problems

Intracerebral aneurysms are rare. However they are potentially life-threatening. Today by means of ultrasound investigations these malformations can occasionally be identified prenatally. In these cases questions of intrauterine therapy, mode and time of delivery and postnatal treatment have to be discussed with the parents. We describe two cases with prenatal diagnosis of intracerebral arteriovenous malformations, diagnostic workup, therapeutic options and fetal outcome.

Fast corticospinal system and motor performance in children: conduction proceeds skill

Transcranial magnetic stimulation and motor performance tests were used to study the correlation between corticospinal maturation and actual motor performance in a group of young school children (n = 10, mean age = 7 years, age range = 6-9 years). The results were compared with normal adults (n = 10, mean age = 24 years, age range = 22-26 years). In children the central conduction time under the preinnervation condition of facilitation and the postexcitatory silent period was similar to that in adults. However, the central conduction time under relaxation, the latency jump (defined as the difference between the two preinnervation conditions), and the stimulus intensity were statistically different between children and adults (P < 0.01-0.001). Children did not reach the same level of performance as adults in any of the motor performance tasks (simple acoustic reaction time, tapping, ballistic movement, tracking, and diadochokinesis) (P < 0.05-0.01). The results indicate that at an early school age, children already possess mature fast corticospinal pathways able to access spinal motoneurons through the pyramidal tract. However, despite the partially adult-like level of neuronal maturation, young school children were not able to perform deliberate motor actions with the same proficiency as adults.

MR findings in pontocerebellar hypoplasia

We present four cases with combined hypoplasia of the cerebellum and the ventral pons-pontocerebellar hypoplasia (PCH). PCH represents an autosomal recessive neurodegenerative disorder with fetal onset. The disease is rare, with less than 20 cases having been reported. The main findings of PCH and the inclusion criteria for our cases can be summarised as progressive microcephaly from birth, pontocerebellar hypoplasia documented by MRI and marked chorea, which may change, later in childhood, to more dystonic patterns. The cerebral cortex becomes progressively atrophic. Motor and mental development are delayed, and epilepsy, mainly tonic-clonic seizures, is frequent. The MRI features in all of our cases were: (1) Hypoplastic cerebellum situated close to the tentorium. The hypoplastic cerebellum has a reduced number of folia, in contrast to the normal number of thin folia in simple cerebellar atrophy. (2) The cerebellar hemispheres are reduced to bean-like or wing-like structures. The cerebellar hemispheres appear to 'float' in the posterior fossa. (3) Markedly hypoplastic ventral pons. (4) Slight atrophy of the supratentorial gyral pattern. (5) Dilated cerebromedullary cistern and fourth ventricle. (6) Delayed myelination of the white matter. (7) No significant disorganisation of brain architecture and no severe corpus callosum defect.

Axonal neuropathy and predominance of type II myofibers in infantile spinal muscular atrophy

Two affected siblings with infantile spinal muscular atrophy (SMA I) presented with generalized muscular hypotonia, which progressed to early death. Quadriceps muscle biopsy did not show the typical neurogenic pattern of spinal muscular atrophy. The histochemical fiber type determination revealed a predominance of type II fibers without type I hypertrophy, an unprecedented finding in spinal muscular atrophy. Sural nerve biopsy exhibited findings typical for axonal neuropathy. In one patient, electrical stimulation of peripheral nerves showed an inexcitability of motor and sensory nerves. Genetic studies revealed homozygous deletions of the telomeric survival motor neuron (SMN) gene and the neuronal apoptosis inhibitory protein (NAIP) gene in the affected children. This is the second case report of molecular genetically proven spinal muscular atrophy associated with axonal neuropathy. We conclude atypical findings on muscle biopsy and evidence of axonal neuropathy are compatible with the diagnosis of infantile spinal muscular atrophy.

High penetrance and pronounced variation in expressivity of GCH1 mutations in five families with dopa-responsive dystonia

We performed a clinical and molecular genetic analysis in members of five families with dopa-responsive dystonia. Four mutations were detected in the gene GCH1 that codes for GTP cyclohydrolase I. Two of these mutations, a delG309 in exon 1 and a C544T transition in exon 5, have not been described before. They result in inactivation of the enzyme by truncation. The remaining two mutations, both A to G transitions, a(-2)g in intron 1 and a(-2)g in intron 2, cause truncation by abnormal splicing. The genotype of family members was correlated to their clinical phenotype (obtained before molecular analysis). Clinical symptoms observed in the families included generalized and focal dystonia, abnormal gait, and subtle signs such as an abnormal writing test. High penetrance (0.8-1.0) was observed in four of five families if minor symptoms and signs were considered. A given mutation was more likely to cause symptoms in females than in males, thus confirming the well-established higher incidence of dopa-responsive dystonia in females than in males.

Absence of transcallosal inhibition following focal magnetic stimulation in preschool children

Focal transcranial magnetic stimulation of the hand-associated motor cortex was used to study normal healthy preschool children (n = 7; mean age, 4.6 years) and adults (n = 7; mean age, 29.4 years) under the conditions of standardized tonic voluntary contraction of small hand muscles. Callosally mediated inhibitory as well as corticospinally mediated inhibitory and excitatory motor effects were investigated. Although children had no detectable transcallosal inhibition, their corticospinally mediated postexcitatory silent period was present (mean, 140.8 +/- 30.2 msec). It was significantly shorter than in adults (mean, 192.5 +/- 32.0 msec). The motor thresholds of the cortically elicited muscle responses, measured as the lowest stimulus intensity, were significantly higher in children (mean, 89 +/- 5%) than in adults (mean, 46 +/- 6%). The corticomuscular latency of transcranially elicited motor responses revealed no difference between children and adults. These observations may reflect maturation processes in the motor system. Maturation of at least some direct corticospinal fibers occurs early in life and is followed by that of intracortical excitatory and inhibitory connections. The maturation of functionally competent callosal connections appears to occur after the age of 5 years.