Introduction:Numerical classification systems for the internal carotid artery (ICA) are available, but modifications have added confusion to the numerical systems. Furthermore, previous classifications may not be applicable uniformly to microsurgical and endoscopic procedures. The purpose of this study was to develop a clinically useful classification system.Materials and Methods:We performed cadaver dissections of the ICA in 5 heads (10 sides) and evaluated 648 internal carotid arteries with computed tomography angiography. We identified specific anatomic landmarks to define the beginning and end of each ICA segment.Results:The ICA was classified into eight segments based on the cadaver and imaging findings: (1) Cervical segment; (2) cochlear segment (ascending segment of the ICA in the temporal bone) (relation of the start of this segment to the base of the styloid process: Above, 425 sides [80%]; below, 2 sides [0.4%]; at same level, 107 sides [20%]; P < 0.0001) (relation of cochlea to ICA: Posterior, 501 sides [85%]; posteromedial, 84 sides [14%]; P < 0.0001); (3) petrous segment (horizontal segment of ICA in the temporal bone) starting at the crossing of the eustachian tube superolateral to the ICA turn in all 10 samples; (4) Gasserian-Clival segment (ascending segment of ICA in the cavernous sinus) starting at the petrolingual ligament (PLL) (relation to vidian canal on imaging: At same level, 360 sides [63%]; below, 154 sides [27%]; above, 53 sides [9%]; P < 0.0001); in this segment, the ICA projected medially toward the clivus in 275 sides (52%) or parallel to the clivus with no deviation in 256 sides (48%; P < 0.0001); (5) sellar segment (medial loop of ICA in the cavernous sinus) starting at the takeoff of the meningeal hypophyseal trunk (ICA was medial into the sella in 271 cases [46%], lateral without touching the sella in 127 cases [23%], and abutting the sella in 182 cases [31%]; P < 0.0001); (6) sphenoid segment (lateral loop of ICA within the cavernous sinus) starting at the crossing of the fourth cranial nerve on the lateral aspect of the cavernous ICA and located directly lateral to the sphenoid sinus; (7) ring segment (ICA between the 2 dural rings) starting at the crossing of the third cranial nerve on the lateral aspect of the ICA; (8) cisternal segment starting at the distal dural ring.Conclusions:The classification may be applied uniformly to all skull base surgical approaches including lateral microsurgical and ventral endoscopic approaches, obviating the need for 2 separate classification systems. The classification allows extrapolation of relevant clinical information because each named segment may indicate potential surgical risk to specific structures.
Purpose: Rapid onset of severe hypertriglyceridemia was quickly recognized in critical COVID-19 patients. Associated causes have been due to secondary hemophagocytic lymphohystiocytosis (HLH) syndrome, medication-induced, or acute liver failure. Statins, omega-3 polyunsaturated acids, niacin, and fibrates are common oral lipid lowering therapy options in patients at risk for hypertriglyceridemia. The severity of hypertriglyceridemia in COVID-19 patients with triglyceride values reaching greater than 1,000 mg/dL put them at a heightened risk of pancreatitis and therefore an essential need to acutely lower their levels. We present a case series of 5 patients who achieved rapid triglyceride lowering through continuous insulin infusion therapy. Methods: A retrospective chart review of 48 critical COVID-19 patients who were admitted from March 22 to April 15, 2020 was conducted. Inclusion criteria consisted of mechanical ventilation and continuous insulin infusion to treat severe hypertriglyceridemia resulting with 5 eligible patients in this case report. Results and Conclusion: In addition to standard oral lipid lowering therapies, continuous insulin infusion successfully treated severe hypertriglyceridemia in critically ill COVID-19 patients. None of the patients experienced pancreatitis or hypoglycemia necessitating cessation of insulin. Further studies are needed to show the optimum dose and duration of insulin infusion as monotherapy and in combination with oral therapies.
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