In vivo two-photon imaging of motoneurons and adjacent glia in the ventral spinal cord.

BACKGROUND: Interactions between motoneurons and glial cells are pivotal to regulate and maintain functional states and synaptic connectivity in the spinal cord. In vivo two-photon imaging of the nervous system provided novel and unexpected knowledge about structural and physiological changes in the grey matter of the forebrain and in the dorsal white matter of the spinal cord. NEW METHOD: Here, we describe a novel experimental strategy to investigate the spinal grey matter, i.e. the ventral horn motoneurons and their adjacent glial cells by employing in vivo two-photon laser-scanning microscopy (2P-LSM) in anesthetized transgenic mice. RESULTS: After retrograde tracer labelling in transgenic mice with cell-specific expression of fluorescent proteins and surgical exposure of the lumbar intumescence groups of motoneurons could be visualized deeply localized in the ventral horn. In this region, morphological responses of microglial cells to ATP could be recorded for an hour. In addition, using in mice with expression of GCaMP3 in astrocytes, physiological Ca2+ signals could be recorded after local noradrenalin application. COMPARISON WITH EXISTING METHODS: Previous in vivo imaging protocols were restricted to the superficial dorsal white matter or upper layers of the dorsal horn. Here, we modified a multi-step procedure originally established for a root-crush injury. We adapted it to simultaneously visualize motoneurons and adjacent glial cells in living animals. CONCLUSION: A modified surgery approach is presented to visualize fluorescently labelled motoneurons and glial cells at a depth of more than 200 µm in the grey matter ventral horn of the mouse spinal cord.

Focal Dystonia in Hemiplegic Upper Limb: Favorable Effect of Cervical Microsurgical DREZotomy Involving the Ventral Horn - A Report of 3 Patients.

BACKGROUND: Focal dystonia in hemiplegic upper limbs is poorly responsive to medications or classical neurosurgical treatments. Only repeated botulinum toxin injections show efficacy, but in most severe cases effects are transient. OBJECTIVES: Cervical DREZ lesioning, which has proven efficacious in hyperspasticity when done deeply (3-5 mm) in the dorsal horn, may have favorable effects on the dystonic component when performed down to, and including, the base of the ventral horn (5-6 mm in depth). METHODS: Three patients underwent deep cervical microsurgical DREZotomy (MDT) for focal dystonia in the upper limb. RESULTS: Hypertonia was reduced, and sustained dystonic postures were suppressed. Residual motor function (hidden behind hypertonia) came to the surface. CONCLUSIONS: Cervical MDT may be a useful armamentarium for treating refractory focal dystonia in the upper limb.