Central nervous system (CNS) development depends upon spontaneous activity (SA) to establish networks. We have discovered that the mouse midbrain has SA expressed most robustly at embryonic day (E) 12.5. SA propagation in the midbrain originates in midline serotonergic cell bodies contained within the adjacent hindbrain and then passes through the isthmus along ventral midline serotonergic axons. Once within the midbrain, the wave bifurcates laterally along the isthmic border and then propagates rostrally. Along this trajectory, it is carried by a combination of GABAergic and cholinergic neurons. Removing the hindbrain eliminates SA in the midbrain. Thus, SA in the embryonic midbrain arises from a single identified pacemaker in a separate brain structure, which drives SA waves across both regions of the developing CNS. The midbrain can self-initiate activity upon removal of the hindbrain, but only with pharmacological manipulations that increase excitability. Under these conditions, new initiation foci within the midbrain become active. Anatomical analysis of the development of the serotonergic axons that carry SA from the hindbrain to the midbrain indicates that their increasing elongation during development may control the onset of SA in the midbrain.

Object Various cutaneous stigmata and congenital anomalies are accepted as sufficient reasons to perform lumbar ultrasonography as a screening tool to rule out occult spinal dysraphism (OSD). The purpose of this study was to correlate presenting cutaneous findings with lumbar ultrasonography results based on a large number of lumbar ultrasonography tests obtained by regional primary care providers. Methods Over the course of 5 years, 1273 infants underwent lumbar ultrasonography screening at a major pediatric tertiary referral center. Of these infants, 1116 had adequate documentation for retrospective chart review. Referral sources included urban academic, urban private practice, and surrounding rural private practitioners. Presence of cutaneous stigmata and/or congenital anomalies and lumbar ultrasonography results were reviewed for all patients. When present, surgical findings were reviewed. Results A total of 943 infants were referred for presumed cutaneous stigmata, the most common of which was a sacral dimple (638 patients [68%]) followed by hairy patch (96 patients [10%]). Other reported cutaneous findings included hemangioma, deviated gluteal fold, skin tag, and skin discoloration. In comparison, 173 patients presented with congenital anomalies, such as imperforate anus (56 patients [32%]) and tracheoesophageal fistula/esophageal atresia (37 patients [21%]), most of which were detected prenatally by fetal ultrasonography. A total of 17 infants underwent surgical exploration. Occult spinal dysraphism was diagnosed in 7 infants in the cutaneous stigmata group and in 10 infants in the group with congenital abnormalities. None of the cutaneous stigmata as recorded were found to be indicative of the presence of OSD. Conclusions Cutaneous markers as currently defined by general practitioners are not useful markers for predicting OSD. The vast majority of findings on lumbar ultrasonography studies performed under these circumstances will be negative.

Object The purpose of this study was to correlate lumbar ultrasound (LUS) and MRI findings in patients suspected of having occult spinal dysraphism (OSD). Methods Over a 5-year period, 1273 consecutive infants underwent an LUS study at a major pediatric tertiary referral center. Of these, 106 patients had abnormal LUS findings suggestive of an OSD, and 103 underwent subsequent MRI studies. The anatomical descriptions of the 2 studies were compared for agreement. Results The average age of the infants was 34 days at the time of the LUS study; OSD was suspected in these patients because of the presence of cutaneous stigmata and congenital defects. The most common anatomical descriptions from the LUS study included a thickened or fatty filum (32 cases), filum cyst (11 cases), and presence of a terminal ventricle or syrinx (9 cases). Using MRI findings as the standard reference, the sensitivity of LUS in detecting a thickened or fatty filum was 20%. The sensitivity of detecting an abnormal conus level at or below L-3 was 76.9%. Conclusions In the patient population chosen to undergo LUS studies, abnormal findings had poor sensitivity at detecting anatomical findings consistent with OSD.

Rostral migration of CM level continues through the first few months of post-natal life, albeit of limited extent. Documentation of continued ascent in a neonate may obviate the need for magnetic resonance imaging.