Innervation of human trigeminal nerve blood vessels

Sphenoid Bone Pneumatisation on Lateral Cephalograms of Patients With Neurofibromatosis Type 1

BACKGROUND/AIM

Neurofibromatosis type 1 (NF1) is an autosomal dominant hereditary disease that causes tumors and many developmental disorders, e.g., cranial dysplasia. The purpose of this retrospective study was to analyse the pneumatisation of the sphenoid bone in NF1.

PATIENTS AND METHODS

The anonymised lateral cephalograms of 166 NF1 patients and 166 age- and sex-matched controls were examined for anterior-posterior sphenoid pneumatisation. The patient group analysis considered whether the patients had been affected by a facial plexiform neurofibroma (FPNF).

RESULTS

Sphenoid pneumatisation was significantly lower in NF1 patients than in controls [odds ratio (OR)=0.184; 95%CI=0.11-0.32; p<0.001]. A FPNF statistically significantly reduced sinus formation in patients (OR=0.38; p=0.002).

CONCLUSION

The condition 'NF1' has an effect on sphenoid pneumatisation. The findings are relevant for planning surgical procedures in this region and confirm current concepts to evaluate NF1 as a histogenesis control gene. The examination technique and basis of calculation presented here are easy-to-use and low-irradiation exposure instruments for screening for differences in sphenoid bone pneumatisation in defined populations.

Perivascular innervation: a multiplicity of roles in vasomotor control and myoendothelial signaling

The control of vascular resistance and tissue perfusion reflect coordinated changes in the diameter of feed arteries and the arteriolar networks they supply. Against a background of myogenic tone and metabolic demand, vasoactive signals originating from perivascular sympathetic and sensory nerves are integrated with endothelium-derived signals to produce vasodilation or vasoconstriction. PVNs release adrenergic, cholinergic, peptidergic, purinergic, and nitrergic neurotransmitters that lead to SMC contraction or relaxation via their actions on SMCs, ECs, or other PVNs. ECs release autacoids that can have opposing actions on SMCs. Respective cell layers are connected directly to each other through GJs at discrete sites via MEJs projecting through holes in the IEL. Whereas studies of intercellular communication in the vascular wall have centered on endothelium-derived signals that govern SMC relaxation, attention has increasingly focused on signaling from SMCs to ECs. Thus, via MEJs, neurotransmission from PVNs can evoke distinct responses from ECs subsequent to acting on SMCs. To integrate this emerging area of investigation in light of vasomotor control, the present review synthesizes current understanding of signaling events that originate within SMCs in response to perivascular neurotransmission in light of EC feedback. Although often ignored in studies of the resistance vasculature, PVNs are integral to blood flow control and can provide a physiological stimulus for myoendothelial communication. Greater understanding of these underlying signaling events and how they may be affected by aging and disease will provide new approaches for selective therapeutic interventions.

Neurovascular development in the embryonic zebrafish hindbrain

The brain is made of billions of highly metabolically active neurons whose activities provide the seat for cognitive, affective, sensory and motor functions. The cerebral vasculature meets the brain's unusually high demand for oxygen and glucose by providing it with the largest blood supply of any organ. Accordingly, disorders of the cerebral vasculature, such as congenital vascular malformations, stroke and tumors, compromise neuronal function and survival and often have crippling or fatal consequences. Yet, the assembly of the cerebral vasculature is a process that remains poorly understood. Here we exploit the physical and optical accessibility of the zebrafish embryo to characterize cerebral vascular development within the embryonic hindbrain. We find that this process is primarily driven by endothelial cell migration and follows a two-step sequence. First, perineural vessels with stereotypical anatomies are formed along the ventro-lateral surface of the neuroectoderm. Second, angiogenic sprouts derived from a subset of perineural vessels migrate into the hindbrain to form the intraneural vasculature. We find that these angiogenic sprouts reproducibly penetrate into the hindbrain via the rhombomere centers, where differentiated neurons reside, and that specific rhombomeres are invariably vascularized first. While the anatomy of intraneural vessels is variable from animal to animal, some aspects of the connectivity of perineural and intraneural vessels occur reproducibly within particular hindbrain locales. Using a chemical inhibitor of VEGF signaling we determine stage-specific requirements for this pathway in the formation of the hindbrain vasculature. Finally, we show that a subset of hindbrain vessels is aligned and/or in very close proximity to stereotypical neuron clusters and axon tracts. Using endothelium-deficient cloche mutants we show that the endothelium is dispensable for the organization and maintenance of these stereotypical neuron clusters and axon tracts in the early hindbrain. However, the cerebellum's upper rhombic lip and the optic tectum are abnormal in clo. Overall, this study provides a detailed, multi-stage characterization of early zebrafish hindbrain neurovascular development with cellular resolution up to the third day of age. This work thus serves as a useful reference for the neurovascular characterization of mutants, morphants and drug-treated embryos.

A novel model of pain sensation using superfused gastrosplenic omentum preparation of anesthetized rats

A pain model for screening analgesics was established in anesthetized rats. The omenta of urethane-anesthetized rats were exteriorized, fixed in a plastic chamber, and superfused with Tyrode solution. Administration of bradykinin (BK) in the chamber elicited the reflex hypertensive response (RHR). Modification of the RHR was tested by topical (in the chamber) or intravenous administration of drugs. The BK dose-response curve was shifted to the right by topical indomethacin. The RHR by BK was inhibited by topical application of a BK B(2) antagonist, (Thi(5,8)-D-Phe(7)-BK), a local anesthetic (2% carbocaine), and by intravenous administration of a ganglion blocker (hexamethonium) or an alpha-adrenergic blocker (dibenamine). The RHR by topical BK was almost completely inhibited by morphine and the suppression was largely reversed by naloxone. The RHR, induced by a threshold dose of BK and inhibited by indomethacin, was potentiated by pretreatment of the omentum with prostaglandin (PG) E(2) or PGI(2). PGE(2) was less potent, but the effect lasted longer than that of PGI(2). Topical administration of a non-acidic analgesic, mepirizole, inhibited the RHR by topical BK by only 20%, but intravenous mepirizole inhibited topical BK by 96.2%, indicating its major central action. This model may be useful for studying analgesics.

Specific and somatotopic functional magnetic resonance imaging activation in the trigeminal ganglion by brush and noxious heat

We used functional magnetic resonance imaging (fMRI) to assess activation in the trigeminal ganglion during innocuous mechanical (brush) and noxious thermal (46 degrees C) stimulation of the face within the receptive fields of each of the three divisions of the trigeminal nerve in healthy volunteers. For both stimulus types, we observed signal changes only in the ipsilateral ganglion, and activation occurred somatotopically, as predicted by the known anatomical segregation of the neurons comprising the ophthalmic (V1), maxillary (V2), and mandibular (V3) divisions of the nerve. Signal decreased after brush stimuli and increased after the application of noxious heat. The abilities to detect somatotopic activation within the ganglion and to segregate non-noxious mechanical from noxious thermal stimuli suggest that fMRI will be valuable for measuring changes in the trigeminal ganglion in human models of neuropathic pain and in the clinical condition itself and may also be useful in the evaluation of pain therapies.