O. Kaiser

Cerebellar mutism--report of four cases.

Abstract.The aim of the present study was to investigate the manifestations of mutism after surgery in children with cerebellar tumors. Speech impairment following cerebellar mutism in children was investigated based on standardized acoustic speech parameters and perceptual criteria. Mutistic and non–mutistic children after cerebellar surgery as well as orthopedic controls were tested pre–and postoperatively. Speech impairment was compared with the localization of cerebellar lesions (i. e. affected lobules and nuclei). Whereas both control groups showed no abnormalities in speech and behavior, the mutistic group could be divided into children with dysarthria in post mutistic phase and children with mainly behavioral disturbances. In the mutistic children involvement of dentate and fastigial nuclei tended to be more frequent and extended than in the nonmutistic cerebellar children.Cerebellar mutism is a complex phenomenon of at least two types. Dysarthric symptoms during resolution of mutism support the anarthria hypothesis, while mainly behavioral changes suggest an explanation independent from speech motor control.

Preserved verb generation in patients with cerebellar atrophy.

A role of the right cerebellar hemisphere has been suggested in linguistic functions. Nevertheless, studies of verb generation in cerebellar patients provide inconsistent results. The aim of the present study was to examine verb generation in a larger group of cerebellar patients with well-defined lesions. Ten subjects with degenerative cerebellar disorders and ten healthy matched controls participated. Subjects had to generate verbs to the blocked presentation of photographs of objects (i.e. four blocks of sixteen objects). As control condition, the objects had to be named. Furthermore, dysarthria was quantified by means of a sentence production and syllable repetition task. Volumetric analysis of individual 3D-MR scans was performed to quantify cerebellar atrophy. Cerebellar patients were slower in the sentence production and syllable repetition tasks, and cerebellar volume was decreased compared to controls. Despite cerebellar atrophy and dysarthria, the answers produced did not differ between patients and controls. In addition, both groups revealed the same amount of decrease in verbal reaction time over blocks (i.e. learning). The results suggest that the role of the cerebellum in verb generation is less pronounced than previously suggested.

Behavioral and affective changes in children and adolescents with chronic cerebellar lesions.

The aim of the present study was to investigate if clinically relevant affective or behavioral changes as described in adults in the cerebellar affective syndrome by Schmahmann and Sherman [The cerebellar cognitive affective syndrome, Brain 121 (1998) 561-579] are likely to occur as a long-term sequelae of cerebellar vermis lesions in children. Site and extent of the vermal lesion were defined on the basis of individual 3D-MRI scans and lesion data were correlated with behavioral and affective changes. Affect and behavior were assessed in children after cerebellar tumor surgery by means of experimenter ratings based on the description of the cerebellar affective syndrome and free ratings by the patients and their parents. Twelve children and adolescents with a former cerebellar astrocytoma surgery without subsequent radiation or chemotherapy participated. Detailed analysis of individual 3D-MR images revealed that lesions affected the vermis in nine children. Experimenter ratings according to Schmahmann revealed no relevant problems in patients. In five out of nine patients with vermal affection somewhat increased thoughtful, anxious or aggressive behavior was reported by patients and parents. In conclusion, minor behavioral and affective changes were present in a subset of children with chronic vermal lesions.

Incidence of Dysarthria in Children with Cerebellar Tumors: A Prospective Study.

The present study investigated dysarthric symptoms in children with cerebellar tumors. Ten children with cerebellar tumors and 10 orthopedic control children were tested prior and one week after surgery. Clinical dysarthric symptoms were quantified in spontaneous speech. Syllable durations were analyzed in syllable repetition and sentence production tasks. Localization of the cerebellar lesions were defined after manual transfer from individual 2D-MR images onto 3D images of a spatially normalized healthy brain. Cerebellar children showed few and mild clinical signs of dysarthria. No difference was present in the sentence production task compared to controls. In five cerebellar children, syllables were prolonged in the syllable repetition task after surgery. Syllable duration normalized in an additional four-week session in all but one case. The MR-analysis showed that superior paravermal cerebellar areas likely involved in dysarthria in adults (paravermal lobules HVI, Crus I) were not significantly affected. In children, speech impairments appear to be rare after cerebellar surgery because tumors most commonly affect posterior-inferior and medial parts of the cerebellum while critical cerebellar regions are likely spared. The results suggest a similar localization of speech functions in the cerebellum in children and adults.

Outcome after Robotic-Assisted Thymectomy in Children and Adolescents with Acetylcholine Receptor Antibody-Positive Juvenile Myasthenia Gravis

Abstract The aim of our study was to describe the long‐term outcomes after robotic‐assisted thymectomy in a cohort of acetylcholine receptor (AChR)‐antibody (Ab)‐positive, generalized juvenile myasthenia gravis (JMG). We retrospectively analyzed a cohort of 18 patients (15 females and 3 males) who underwent robotic‐assisted thymectomy. At the time of diagnosis, 12/18 patients were prepubertal; the mean age was 9.8 years at the onset of the disease. All patients received therapy with pyridostigmine; additional immunotherapy included: corticosteroid therapy in 18/18, azathioprine in 14/18 patients, mycophenolate mofetil in 4/18, and cyclosporine in 1/18 patients. Eight patients received intravenous immunoglobulin and four plasma exchange. The mean age of patients at thymectomy was 11.7 years (range: 4.2‐16 years). The mean duration of postoperative stay was 2.9 days. Thymectomy was followed by gradual clinical improvement (39% patients achieved clinical remission) and dose reduction in steroid therapy in all patients during the follow‐up period (mean: 27.4 months). In children and adolescents with AChR‐Ab‐positive JMG, thymectomy has a beneficial effect on the weaning off immunosuppressive therapy in patients with generalized symptoms and should be considered as a part of multimodal therapy. Robotic‐assisted thymectomy is a safe procedure with low morbidity and a comparable clinical outcome compared with the open sternal procedure.

Cerebellar-dependent associative learning is impaired in very preterm born children and young adults

Preterm birth incorporates an increased risk for cerebellar developmental disorders likely contributing to motor and cognitive abnormalities. Experimental evidence of cerebellar dysfunction in preterm subjects, however, is sparse. In this study, classical eyeblink conditioning was used as a marker of cerebellar dysfunction. Standard delay conditioning was investigated in 20 adults and 32 preschool children born very preterm. Focal lesions were excluded based on structural magnetic resonance imaging. For comparison, an equal number of matched term born healthy peers were tested. Subgroups of children (12 preterm, 12 controls) were retested. Preterm subjects acquired significantly less conditioned responses (CR) compared to controls with slower learning rates. A likely explanation for these findings is that preterm birth impedes function of the cerebellum even in the absence of focal cerebellar lesions. The present findings are consistent with the assumption that prematurity results in long-term detrimental effects on the integrity of the cerebellum. It cannot be excluded, however, that extra-cerebellar pathology contributed to the present findings.

OP42 – 2499: Juvenile myasthenia gravis: clinical course and outcome in 21 patients from a single neuromuscular centre in Germany

Objective Myasthenia gravis is a rare autoimmune disorder of neuromuscular transmission caused by production of specific antibodies against the structures of the neuromuscular junction. Clinical signs and course of juvenile myasthenia gravis (JMG) may differ compared to adults and an early diagnosis is crucial to start an adequate therapy. Until now, data concerning effect and outcome after thymectomy as well optimal therapeutic strategies in JMG are spared. Methods We retrospectively analysed a cohort of patients with JMG in our neuromuscular centre. Since 2009, 21 patients (19 female/2 male) were diagnosed. Results At the time of diagnosis, 13/21 patients were pre-pubertal, six of them showed first symptoms at the age between 18 months to 6 years. Isolated ocular symptoms were present in 7 patients at onset, 4 of them developed bulbar symptoms or generalised muscular weakness over time. Positive nicotinic acetylcholine receptor titre was found in 16 of generalised cases and in one of three isolated ocular cases, one patient was positive for muscle specific kinase-antibodies. Twenty patients responded to pyridostigmine, additional immunotherapy included: corticosteroids in 19/21, azathioprine in 12/21 patients, in two patients mycophenolate mofetil and cyclosporine respectively. Eight patients required intravenous immunoglobulines, plasma exchange was performed in four patients. Thymectomy was performed in 17/21 patients (age range 4 to 16 years) and followed by subsequently clinical improvement in 15 patients and reduction of immunotherapy in 13. Conclusion An early therapy and thymectomy seem to have positive influence on the outcome in JMG with generalised symptoms. Early thymectomy led to a shortened period of immunotherapy (in particular corticosteroids) and their possible side-effects on the growing organism. A national registry will be helpful to collect important data concerning early symptoms and applied therapy; this will be the basic platform for further development of diagnostic strategies and management in this age group.