Ataxia in children: early recognition and clinical evaluation

Background: Ataxia is a sign of different disorders involving any level of the nervous system and consisting of impaired coordination of movement and balance. It is mainly caused by dysfunction of the complex circuitry connecting the basal ganglia, cerebellum and cerebral cortex. A careful history, physical examination and some characteristic maneuvers are useful for the diagnosis of ataxia. Some of the causes of ataxia point toward a benign course, but some cases of ataxia can be severe and particularly frightening. Methods: Here, we describe the primary clinical ways of detecting ataxia, a sign not easily recognizable in children. We also report on the main disorders that cause ataxia in children. Results: The causal events are distinguished and reported according to the course of the disorder: acute, intermittent, chronic-non-progressive and chronic-progressive. Conclusions: Molecular research in the field of ataxia in children is rapidly expanding; on the contrary no similar results have been attained in the field of the treatment since most of the congenital forms remain fully untreatable. Rapid recognition and clinical evaluation of ataxia in children remains of great relevance for therapeutic results and prognostic counseling

Transverse cervical megapophysis as an uncommon cause of torticollis

Congenital abnormalities of the spine are not uncommon in the general population and can be asymptomatic. Transverse megapophysis is a congenital anomaly manifested as an enlargement of the transverse processes, typically common in the lumbar vertebrae. Here, we describe a 4-month-old infant female with episodes of shooting pain and torticollis. At the beginning of the third month, the parents noticed she held her neck inclined towards the left side in a changeable way, and movement caused discomfort and crying. Muscular tonus, laboratory investigations, ECG and heart and transfontanellar ultrasound were normal. A cervical CT and MRI displayed at the C7 level a megapophysis transverse involving both sides. Treatment with no steroidal anti-inflammatory drugs twice a day and, after a few days, symptoms solved. At 8 months follow-up, neck maintains its natural position and no unmotivated pain has been noticed. Transverse C7 megapophysis presenting with torticollis is an example of a cause of severe pain in infancy, and it should be considered in the differential diagnosis of infantile torticollis. Keywords: Transverse cervical megapophysis, Torticollis, Bertolotti syndrom

Cervical neurenteric cyst and Klippel-Feil syndrome: An abrupt onset of myelopathic signs in a young patient

Neurenteric cysts (NECs), also called enterogenous cysts or enterogenic cysts, are congenital malformative anomalies of endodermal origin that manifest with a variety of disorders, including spine anomalies. Neurenteric cysts are uncommon developmental disorders reported in 0.7%–1.3% of all spinal tumors. Klippel-Feil syndrome (KFS) defines a malformative spine disorder presenting with congenital fusion of cervical vertebrae and/or other parts of the spine. In patients with KFS, NECs are rarely reported; they may be silent for long periods of time, showing a slow progressive course or manifesting with an acute, severe neurological presentation or with fluctuating myelopathic symptoms. We report a young patient affected by KFS associated with a NEC which, in a short period of time, progressively caused myelopathic symptomatology. Surgical intervention resulted in resolution of the neurological signs. Keywords: Neurenteric cyst, Klippel-Feil syndrome, Intramedullary cys

Removing striping artifacts in light-sheet fluorescence microscopy: a review

In recent years, light-sheet fluorescence microscopy (LSFM) has found a broad application for imaging of diverse biological samples, ranging from sub-cellular structures to whole animals, both in-vivo and ex-vivo, owing to its many advantages relative to point-scanning methods. By providing the selective illumination of sample single planes, LSFM achieves an intrinsic optical sectioning and direct 2D image acquisition, with low out-of-focus fluorescence background, sample photo-damage and photo-bleaching. On the other hand, such an illumination scheme is prone to light absorption or scattering effects, which lead to uneven illumination and striping artifacts in the images, oriented along the light sheet propagation direction. Several methods have been developed to address this issue, ranging from fully optical solutions to entirely digital post-processing approaches. In this work, we present them, outlining their advantages, performance and limitations

Removing striping artifacts in light-sheet fluorescence microscopy: a review

In recent years, light-sheet fluorescence microscopy (LSFM) has found a broad application for imaging of diverse biological samples, ranging from sub-cellular structures to whole animals, both in-vivo and ex-vivo, owing to its many advantages relative to point-scanning methods. By providing the selective illumination of sample single planes, LSFM achieves an intrinsic optical sectioning and direct 2D image acquisition, with low out-of-focus fluorescence background, sample photo-damage and photo-bleaching. On the other hand, such an illumination scheme is prone to light absorption or scattering effects, which lead to uneven illumination and striping artifacts in the images, oriented along the light sheet propagation direction. Several methods have been developed to address this issue, ranging from fully optical solutions to entirely digital post-processing approaches. In this work, we present them, outlining their advantages, performance and limitations

Whole-brain functional imaging to highlight differences between the diurnal and nocturnal neuronal activity in zebrafish larvae

Most living organisms show highly conserved physiological changes following a 24-hour cycle which goes by the name of circadian rhythm. Among experimental models, the effects of light-dark cycle have been recently investigated in the larval zebrafish. Owing to its small size and transparency, this vertebrate enables optical access to the entire brain. Indeed, the combination of this organism with light-sheet imaging grants high spatio-temporal resolution volumetric recording of neuronal activity. This imaging technique, in its multiphoton variant, allows functional investigations without unwanted visual stimulation. Here, we employed a custom two-photon light-sheet microscope to study whole-brain differences in neuronal activity between diurnal and nocturnal periods in larval zebrafish. We describe for the first time an activity increase in the low frequency domain of the pretectum and a frequency-localised activity decrease of the anterior rhombencephalic turning region during the nocturnal period. Moreover, our data confirm a nocturnal reduction in habenular activity. Furthermore, whole-brain detrended fluctuation analysis revealed a nocturnal decrease in the self-affinity of the neuronal signals in parts of the dorsal thalamus and the medulla oblongata. Our data show that whole-brain nonlinear light-sheet imaging represents a useful tool to investigate circadian rhythm effects on neuronal activity.Comment: 18 pages, 6 figure

Effects of excitation light polarization on fluorescence emission in two-photon light-sheet microscopy

Light-sheet microscopy (LSM) is a powerful imaging technique that uses a planar illumination oriented orthogonally to the detection axis. Two-photon (2P) LSM is a variant of LSM that exploits the 2P absorption effect for sample excitation. The light polarization state plays a significant, and often overlooked, role in 2P absorption processes. The scope of this work is to test whether using different polarization states for excitation light can affect the detected signal levels in 2P LSM imaging of typical biological samples with a spatially unordered dye population. Supported by a theoretical model, we compared the fluorescence signals obtained using different polarization states with various fluorophores (fluorescein, EGFP and GCaMP6s) and different samples (liquid solution and fixed or living zebrafish larvae). In all conditions, in agreement with our theoretical expectations, linear polarization oriented parallel to the detection plane provided the largest signal levels, while perpendicularly-oriented polarization gave low fluorescence signal with the biological samples, but a large signal for the fluorescein solution. Finally, circular polarization generally provided lower signal levels. These results highlight the importance of controlling the light polarization state in 2P LSM of biological samples. Furthermore, this characterization represents a useful guide to choose the best light polarization state when maximization of signal levels is needed, e.g. in high-speed 2P LSM.Comment: 16 pages, 4 figures. Version of the manuscript accepted for publication on Biomedical Optics Expres