The Underlying Pathogenesis of Neurovascular Compression Syndromes: A Systematic Review

Abstract

Neurovascular compression syndromes (NVC) are challenging disorders resulting from the compression of cranial nerves at the root entry/exit zone. Clinically, we can distinguish the following NVC conditions: trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia. Also, rare cases of geniculate neuralgia and superior laryngeal neuralgia are reported. Other syndromes, e.g., disabling positional vertigo, arterial hypertension in the course of NVC at the CN IX-X REZ and torticollis, have insufficient clinical evidence for microvascular decompression. The exact pathomechanism leading to characteristic NVC-related symptoms remains unclear. Proposed etiologies have limited explanatory scope. Therefore, we have examined the underlying pathomechanisms stated in the medical literature. To achieve our goal, we systematically reviewed original English language papers available in Pubmed and Web of Science databases before 2 October 2021. We obtained 1694 papers after eliminating duplicates. Only 357 original papers potentially pertaining to the pathogenesis of NVC were enrolled in full-text assessment for eligibility. Of these, 63 were included in the final analysis. The systematic review suggests that the anatomical and/or hemodynamical changes described are insufficient to account for NVC-related symptoms by themselves. They must coexist with additional changes such as factors associated with the affected nerve (e.g., demyelination, REZ modeling, vasculature pathology), nucleus hyperexcitability, white and/or gray matter changes in the brain, or disturbances in ion channels. Moreover, the effects of inflammatory background, altered proteome, and biochemical parameters on symptomatic NVC cannot be ignored. Further studies are needed to gain better insight into NVC pathophysiology.

Keywords: glossopharyngeal neuralgia; hemifacial spasm; neurovascular compression syndromes; neurovascular conflicts; pathogenesis; trigeminal neuralgia.

Figure 1

The flow-chart of publications included process.

Figure 2

The graphical summary of the underlying pathogenesis of neurovascular compression syndromes based on performed systematic review. Legend as follow: AD, axial diffusivity; ADC, apparent diffusion coefficient; AMPK, adenosine monophosphate-activated protein kinase; CPA, cerebellopontine angle; FA, fractional anisotropy; MD, mean diffusivity; MMP-2, metalloproteinase-2; NLRP3, nucleotide-binding domain (NOD)-like receptor protein 3; lncRNA, Long non-coding RNA; RD, radial diffusivity; REZ, root entry/exit zone; WM, white matter.

Figure 3

The proposed chain of events leading to neurovascular compression-related symptoms: vascular compression in transition zone → demyelination → nucleus hyperexcitability → symptoms. Not all factors mentioned in Figure 2 are presented here. Future research is needed to understand their role. NVC, neurovascular compression.