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Meckel’s cave is a dural recess in the posteromedial portion of the middle cranial fossa that acts as a conduit for the trigeminal nerve between the prepontine cistern and the cavernous sinus, and houses the Gasserian ganglion and proximal rootlets of the trigeminal nerve. It serves as a major pathway in perineural spread of pathologies such as head and neck neoplasms, automatically upstaging tumours, and is a key structure to assess in cases of trigeminal neuralgia. The purpose of this pictorial review is threefold: (1) to review the normal anatomy of Meckel’s cave; (2) to describe imaging findings that identify disease involving Meckel’s cave; (3) to present case examples of trigeminal and non-trigeminal processes affecting Meckel’s cave. Teaching points • Meckel’s cave contains the trigeminal nerve between prepontine cistern and cavernous sinus. • Assessment is essential for perineural spread of disease and trigeminal neuralgia. • Key imaging: neural enhancement, enlargement, perineural fat/CSF effacement, skull base foraminal changes.

Importance Magnetic resonance imaging (MRI) continues to be performed for cervical clearance of obtunded blunt trauma, despite poor evidence regarding its utility after a normal computed tomographic (CT) finding. Objective To evaluate the utility and cost-effectiveness of MRI vs no follow-up after a normal cervical CT finding in patients with obtunded blunt trauma. Design, Setting and Participants This cost-effectiveness analysis evaluated an average patient aged 40 years with blunt trauma from an institutional practice. The analysis used a Markov decision model over a lifetime horizon from a societal perspective with variables from systematic reviews and meta-analyses and reimbursement rates from the Centers for Medicare & Medicaid Services, National Spinal Cord Injury Database, and other large published studies. Data were collected from the most recent literature available. Interventions No follow-up vs MRI follow-up after a normal cervical CT finding. Results In the base case of a 40-year-old patient, the cost of MRI follow-up was $14 185 with a health benefit of 24.02 quality-adjusted life-years (QALY); the cost of no follow-up was $1059 with a health benefit of 24.11 QALY, and thus no follow-up was the dominant strategy. Probabilistic sensitivity analysis showed no follow-up to be the better strategy in all 10 000 iterations. No follow-up was the better strategy when the negative predictive value of the initial CT was relatively high (>98%) or the risk of an injury treated with a cervical collar turning into a permanent neurologic deficit was higher than 25% or when the risk of a missed injury turning into a neurologic deficit was less than 58%. The sensitivity and specificity of MRI were varied simultaneously in a 2-way sensitivity analysis, and no follow-up remained the optimal strategy. Conclusions and Relevance Magnetic resonance imaging had a lower health benefit and a higher cost compared with no follow-up after a normal CT finding in patients with obtunded blunt trauma to the cervical spine, a finding that does not support the use of MRI in this group of patients. The conclusion is robust in sensitivity analyses varying key variables in the model. More literature on these key variables is needed before MRI can be considered to be beneficial in the evaluation of obtunded blunt trauma.

BACKGROUND AND PURPOSE: Evaluation for blunt cerebrovascular injury has generated immense controversy with wide variations in recommendations regarding the need for evaluation and the optimal imaging technique. We review the literature and determine the most cost-effective strategy for evaluating blunt cerebrovascular injury in trauma patients. MATERIALS AND METHODS: A comprehensive literature review was performed with data extracted to create a decision-tree analysis for 5 different strategies: anticoagulation for high-risk (based on the Denver screening criteria) patients, selective DSA or CTA (only high-risk patients), and DSA or CTA for all trauma patients. The economic evaluation was based on a health care payer perspective during a 1-year horizon. Statistical analyses were performed. The cost-effectiveness was compared through 2 main indicators: the incremental cost-effectiveness ratio and net monetary benefit. RESULTS: Selective anticoagulation in high-risk patients was shown to be the most cost-effective strategy, with the lowest cost and greatest effectiveness (an average cost of $21.08 and average quality-adjusted life year of 0.7231). Selective CTA has comparable utility and only a slightly higher cost (an average cost of $48.84 and average quality-adjusted life year of 0.7229). DSA, whether performed selectively or for all patients, was not optimal from both the cost and utility perspectives. Sensitivity analyses demonstrated these results to be robust for a wide range of parameter values. CONCLUSIONS: Selective CTA in high-risk patients is the optimal and cost-effective imaging strategy. It remains the dominant strategy over DSA, even assuming a low CTA sensitivity and irrespective of the proportion of patients at high-risk and the incidence of blunt cerebrovascular injury in high-risk patients.

We thank van Eijck et al for their effort in addressing the important, relevant question regarding the follow-up on coiled basilar aneurysms in “Clinical and Imaging Follow-Up of Patients with Coiled Basilar Tip Aneurysms Up to 20 Years.”[1][1] However, we would like to raise a few questions

We would like to thank Heit et al[1][1] for their study “Cerebral Angiography for Evaluation of Patients with CT Angiogram-Negative Subarachnoid Hemorrhage: An 11-Year Experience” on the utility of digital subtraction angiography in patients with negative findings on CT angiography and

Aim To evaluate whether qualitative and quantitative assessments of stylomandibular tunnel asymmetry are useful in lesion localization and differentiation. Materials and methods The stylomandibular tunnel was measured in 60 control patients at CT to determine normal side-to-side variation. Twenty-one patients in the study group with suprahyoid neck masses were divided into two subgroups, those with widening and those with narrowing of the pathological side. Surgical and pathological findings in these subgroups were compared for site of origin and histology. Results Stylomandibular tunnel diameters in the control group had a mean variation of 0.9 mm (range: 0–3 mm, SD: 0.83 mm). Two-tailed t-test yielded a p-value of 0.018 for a variation of 3 mm and this was chosen as the threshold for disease. The widened stylomandibular tunnel group all had parotid gland lesions extending into the pre-styloid parapharyngeal space. The narrowed stylomandibular tunnel group had adenopathy, schwannomas, and paragangliomas/glomus vagale tumours arising from the post-styloid parapharyngeal space. Conclusion Qualitative assessment for asymmetry of the stylomandibular tunnel surpass the 3 mm threshold for pathology. Widening of the stylomandibular tunnel is primarily from deep lobe parotid lesions extending into the pre-styloid parapharyngeal space. Narrowing of the stylomandibular tunnel can be from adenopathy, schwannomas, and paragangliomas arising from the post-styloid parapharyngeal space.