Chiari 1: Is decompression always necessary previous to scoliosis surgery?

The association between Chiari 1 malformation and scoliosis is well known in the literature. Prevalence has increased after the advent of magnetic resonance imaging. In children with this association, prophylactic suboccipital decompression prior to scoliosis correction is a common surgical procedure although the rationale for this surgical management and whether not performing it may lead to spinal cord injury has not been clearly elucidated. We conducted a systematic review of the literature with the aim to obtain strong data to support the hypothesis that it is safe to proceed with scoliosis correction without prior prophylactic suboccipital decompression for Chiari 1 in an asymptomatic population. Using the Prisma methodology, we analyzed 3250 studies published between 1972 and 2018. Only four studies met the inclusion criteria. None of the studies had a level of evidence high enough to recommend prophylactic decompression previous to correction of the spinal deformity.

Aneurysmal bone cyst and osteoblastoma: an extremely rare combination in the pediatric spine.

STUDY DESIGN: Case report. OBJECTIVE: To report the clinical and imaging findings of a patient with the extremely rare association of aneurysmal bone cyst and osteoblastoma in the cervical spine. To our knowledge, only three cases have been reported in the published literature in children under 16 years of age with this condition in the cervical spine. METHODS: The patient's history, physical examination, imaging findings, and management with a complete 4-year medical history, surgical intervention and radiological follow-up are reported. RESULTS: A 4-year 11-month-old boy was diagnosed with aneurysmal bone cyst in association of osteoblastoma and was treated with CT-guided intralesional injection calcitonin and methylprednisolone. During the course of intralesional therapy, a pathological fracture of C2 was produced. Subsequently, a widened intralesional excision and instrumented fusion from occiput to cervical spine (C0-C4) was performed. CONCLUSION: The association of aneurysmal bone cyst and osteoblastoma in spine is extremely rare. Although both are benign lesions, in the cervical location, complete removal of the tumors is challenging. Wide resection with reconstruction of the segments for stability associated with adjuvant treatment with calcitonin and corticosteroids provides a good option.

Anomalias vertebrales y anomalias asociadas / Vertebral anomalies and associated anomalies

Las anomalías vertebrales son trastornos embriopáticos.Muchas de ellas concurren con anomalías de otros órganos,en forma aislada,casual o formando parte de asociaciones y síndromes.El objetivo de este trabajo ha sido evaluar la incidencia de anomalías asociadas en los pacientes con anomalías vertebrales.Se evaluaron 1029 pacientes con anomalías de columna,sus registros fueron efectuados desde 1972 hasta el 2000.fueron excluidos del presente los pacientes con mielomeningocele y enanismo tipificados.Con el objetivo de obtener datos que probablemente fueran más completos se efectuaron tres mediciones:a)el grupo total(1029)b)el grupo de pacientes intervenidos quirúrgicamente por su deformidad espinal(390)c)el grupo de pacientes seguidos más allá de los 15 años(124).Como conclusión observamos distintos valores de incidencia de malformaciones asociadas a las deformidades espinales comparados con resultados de otros autores,nuestra prevalecencia es menor.A pesar de los distintos estudios sometidos a grupos de pacientes y a distinto tiempo de evolución los datos de los tres grupos parecen ser coincidentes

Harrington instrumentation without arthrodesis and consecutive distraction program for young children with severe spinal deformities. Experience and technical details.

The treatment of severe spinal deformities in childhood is a great challenge. The nonoperative treatment is not always successful, and correction with spinal fusion is not usually the most desirable goal because it may result in a straighter but shorter trunk. Spinal instrumentation without arthrodesis is an alternative to these difficult decisions that allows child growth with control of the deformity. At the same time that there is considerable improvement in the natural history of these deformities, this treatment presents great morbidity. The combination of Harrington instrumentation and consecutive distractions is a difficult program but it has been the best answer for these complicated patients up to now.

Neural control of vergence eye movements: neurons encoding vergence velocity.

Single-unit recordings were made from midbrain areas in monkeys trained to make both conjugate and disjunctive (vergence) eye movements. Previous work had identified cells with a firing rate proportional to the vergence angle, without regard to the direction of conjugate gaze. The present study describes the activity of neurons that burst for disjunctive eye movements. Convergence burst cells display a discrete burst of activity just before and during convergence eye movements. For most of these cells, the profile of the burst is correlated with instantaneous vergence velocity and the number of spikes in the burst is correlated with the size of the vergence movement. Some of these cells also have a tonic firing rate that is positively correlated with vergence angle (convergence burst-tonic cells). Divergence burst cells have similar properties, except that they fire for divergent and not convergent movements. Divergence burst cells are encountered far less often than convergence burst cells. Both convergence and divergence burst cells were found in an area of the mesencephalic reticular formation just dorsal and lateral to the oculomotor nucleus. Convergence burst cells were also recorded in another more dorsal mesencephalic region, rostral to the superior colliculus. Both of the areas also contain cells that encode vergence angle. Models of the vergence system derived from psychophysical data imply the existence of a vergence integrator, the output of which is vergence angle. Some models also suggest the presence of a parallel element that improves the frequency response of the vergence system, but has no effect on the steady-state behavior of the system. Vergence burst cells would be suitable inputs to a vergence integrator. By providing a vergence velocity signal to motoneurons, they may improve the dynamic response of the vergence system. The behavior of vergence burst cells during vergence movements is similar to that of the medium-lead burst cells during saccades. The proposed roles for vergence velocity cells are analogous to those of the saccadic burst cells. In this respect, the neural organization of the vergence system resembles that of the saccadic system, despite the distinct difference in the kinematics of these two types of eye movements.