Magnetic resonance diffusion weighted imaging using constrained spherical deconvolution-based tractography of the extracranial course of the facial nerve.

OBJECTIVE: To evaluate the accuracy of magnetic resonance diffusion weighted imaging (DWI) featuring constrained spherical deconvolution-based tractography in tracking the extracranial course of the facial nerve to provide a reliable facial nerve map to facilitate well-tolerated and effective tumor resection. STUDY DESIGN: Magnetic resonance DWI was conducted on 2 parotid-healthy cadaveric patients with various protocols to identify the best representation of the extracranial facial nerve tract. This was subsequently correlated to dissection of the facial nerves to ascertain anatomic validation. These protocols were applied to 2 live, parotid-healthy patients to assess feasibility of in vivo facial nerve tract identification. RESULTS: Correlations between imaged tracts and the anatomic course of the extracranial facial nerve were identified to an accuracy of 1 mm. The main trunk and bifurcation tracts were identified on imaging. Fractional anisometry values in cadaveric and live patients were within the range expected for the facial nerve within the parotid gland. CONCLUSIONS: Our results indicated the potential for accurate 3-dimensional visualization of the extracranial course of the facial nerve, which could have diagnostic implications in differentiating benign from malignant tumors and, crucially, neural involvement. Preoperative planning applications of DWI could help in planning surgical approaches and providing focused counseling.

A cadaveric study of aortic arch variation in an Irish population.

AIM: The aim of this study is to investigate the incidence of variation in the branching pattern of aortic arch (AA) vessels in an Irish population. METHOD: A cadaveric study of 24 subjects was conducted. The vessels of the AA were identified, their branching patterns were noted and photographed and the following measurements were recorded: the angle of the AA to the coronal plane, the distance from the midline to the brachiocephalic trunk (BCT); the left common carotid artery (LCC) ; the left subclavian artery (LSC), the distance between the BCT and the right subclavian artery (RSC); the RSC and the right vertebral artery (RVA), and between the LSC and left vertebral artery (LVA). RESULTS: The 'normal' branching pattern (BCT, LCC, LSC) was observed in 79%. Thirteen percent had a two-branched AA (bovine variant), while the remainder had an aberrant left vertebral artery (LVA) originating from the AA. The mean distances from the midline to the BCT, LCC and LSC were 9.1, 10.8 and 21.4 mm, respectively. Mean distance from BCT to RSC was 34.09 mm. The mean distance from LSC to LVA was 39.79 mm, and the mean distance from RSC to RVA was 23.38 mm. The mean angle of the AA to the coronal plane was 59.02°. CONCLUSION: This is the first study documenting the rates of variation of the AA in Ireland. Variation of AA branching is of radiological and surgical significance, particularly in the diagnosis and treatment of thoracic and head and neck diseases. Awareness of these variations is particularly relevant for interventionalists who access these vessels during endovascular surgery.

Unusual Morel-Lavallee lesion of the knee region in an elderly patient.

The Morel-Lavallee lesion (MLL) of the knee region has been described in the Orthopaedic literature, and all of those were fit and healthy young participants sustaining sports-related trauma to the knee. We describe a case of an elderly woman, on aspirin and prophylactic clexane, who sustained a low-energy injury to the right knee and developed an MLL of the knee region. A delayed recognition, led to the persistence of the MLL as a diffuse haematoma, which subsequently became colonised with methicillin-resistant Staphylococcus aureus We discuss the management of a case and highlight the importance of early identification and management of MLL of the knee region. Further evidence needs to be collected about MLL lesions in elderly, frail patients who are anticoagulated, and have increased risk of falls. This cohort of patients is more vulnerable to bleeding and infection than a fit, young adult population.