Variations in Source and Pattern of Arterial Supply to the Trigeminal Ganglion with Clinical Relevance

Abstract Body : Introduction: Trigeminal ganglia (TG) are bilateral collections of first-order pseudounipolar neuron cell bodies from the ophthalmic (CN V1), maxillary (CN V2), and mandibular (CN V3) divisions of the trigeminal nerve which collectively convey sensory afferent information from the face, scalp, oral mucosa, teeth, and meninges. Each TG resides inside Meckel’s cave, a dural recess along the trigeminal impression near the petrous apex of the temporal bone. While the TG is known to receive blood from branches associated with the internal carotid artery (ICA), middle meningeal artery (MMA), accessory meningeal artery (AMA), or superior cerebellar artery (SCA), existing information about the prevalence and patterns of blood supply to the TG is limited despite their high clinical relevance to basicranial surgeries. The objective of this study is to investigate the source and pattern of arterial supply to TG and discuss their clinical relevance.

Materials and Methods: Left and right TG were examined on 63 embalmed human cadavers from an ethically approved anatomical donor program. TG were excluded from analysis if arterial supply was compromised by previous dissection or was inconclusive; the remaining 89 TG were compiled. Sources and patterns of gross arterial supply were recorded, and select specimens were photographed (iPad Pro, Apple Inc.). Color replacement was utilized to aid structure identification (Adobe Photoshop 20.0.9) in the photograph images. A literature review was conducted, and a neurosurgeon was interviewed to convey the clinical relevance of the arterial supply variations.

Results: Sixty-seven TG (75.3%) received arterial supply from only one artery: 49 from ICA, 11 from AMA, and 7 from MMA. The blood supply for 22 TG (24.7%) had two distinct arterial contributions and was further classified as either anastomotic or dual-independent. Occurrences of anastomotic supply included 10 from ICA and AMA and 5 from ICA and MMA, while dual-independent supplies occurred from ICA and AMA for 3 TG and from ICA and MMA for 4 TG. No source of gross arterial supply from SCA was discovered. Notably, some AMAs pierced the basicranium via isolated foramen (instead of foramen ovale), and although all TG were supplied from their deep surface, one specimen received its supply from a branch of MMA that traversed over CN V2 before coursing between CN V1 and CN V2 and turning back to singly supply the TG.

Discussion: Arterial supply to the TG appears to predominate from a singular branch of ICA, although AMA and MMA represent possible alternatives for primary supply. Anastomotic or dual-independent supplies were less frequent but obvious when present, and ICA was involved in all occurrences of dual supply. Since no occurrences of SCA supply were discovered, a focused study on tentorial branches supplying TG with a more strategic dissection approach may be warranted. Results from this study are relevant to surgical treatment of meningiomas, schwannomas, and dural arteriovenous fistulas within Meckel’s cave area as they have the potential to compromise blood flow to the TG and affect TG function. These variations should be considered when deliberating treatment of these conditions, and this report provides valuable data and photographic references to aid this process.