Pain is normally mediated by nociceptive Aδ and C fibers, while Aβ fibers signal touch. However, after nerve injury, Aβ fibers may signal pain. Using a genetic model, we tested the hypothesis that phenotypic switching in neurotransmitters expressed by Aβ afferents might account for heritable differences in neuropathic pain behavior. The study examined selection-line rats in which one line, high autotomy (HA), shows higher levels of spontaneous pain in the neuroma neuropathy model, and of tactile allodynia in the spinal nerve ligation (SNL) model, than the companion low autotomy (LA) line. Changes in calcitonin gene-related peptide (CGRP) and Substance P expression were evaluated immunohistochemically in L4 and L5 dorsal root ganglia 7 days after SNL surgery. Expression of CGRP was decreased in axotomized small- and medium-diameter neurons in both rat lines. However, in HA but not in LA rats, there was a tenfold increase in CGRP immunoreactivity (CGRP-IR) in large-diameter neurons. Corresponding changes in CGRP-IR in axon terminals in the nucleus gracilis were also seen. Finally, there were indications of enhanced CGRP neurotransmission in deep laminae of the dorsal horn. Substance P immunoreactivity was also upregulated in large-diameter neurons, but this change was similar in the 2 lines. Our findings suggest that phenotypic switching contributes to the heritable difference in pain behavior in HA vs LA rats. Specifically, we propose that in HA rats, but less so in LA rats, injured, spontaneously active Aβ afferents both directly drive CGRP-sensitive central nervous system pain-signaling neurons and also trigger and maintain central sensitization, hence generating spontaneous pain and tactile allodynia.

No abstract

To describe the clinical course and prognosis of pediatric idiopathic intracranial hypertension (IIH) and examine the preferred management setting. IIH is characterized by increased intracranial pressure and is often associated with headaches and visual complaints. IIH is a preventable cause of vision loss in children. Hence, a rapid diagnosis followed by prompt treatment and follow-up is essential. However, standardization of the management of IIH in the pediatric population is not well established. Computerized medical charts of all 82 pediatric (< 18 years) patients diagnosed with IIH between 2007 and 2018 in the metropolitan area of Jerusalem were reviewed. Comparison was made between children followed in a multidisciplinary clinic in tertiary centers and those followed elsewhere. Detailed demographic and clinical data, as well as data regarding the follow-up setting and clinical course of the disease, were collected and analyzed. Recurrent IIH-related hospital returns were selected as a measurable marker for the uncontrolled disease. Recurrent IIH-related hospital return rate was significantly lower and occurred later among children followed by multidisciplinary teams compared to individual experts. Follow-up in multidisciplinary clinics improve the quality of life, and financial burden and may prevent permanent visual impairment in children with IIH.

No abstract