Comment on “The relationship of the posterior inferior cerebellar artery to the cranial nerves VII–XII”

Saylam et al. (2007) are to be congratulated for\udtheir recent article on the relationship of the posterior\udinferior cerebellar artery (PICA) with the cranial\udnerves, with particular reference to the microsurgery\udof this region. However, we would like to bring some\udadditional observations to the attention of the\udauthors.\udThe study of the vessels of the brain base is one\udof our fields of research (De Caro et al., 1990, 1991,\ud1995, 1996, 1998, 2000; Porzionato et al., 2004;\udMacchi et al., 2005; Parenti et al., 2005). We studied\udthe PICA on 40 autoptic brains (Macchi et al., 2004),\udand we were able to analyze the origin and the whole\udcourse of 80 PICAs, with reference to the five segments\uddescribed by Lister et al. (1982), which were\udrecognizable on both sides. It is a pity that Saylam\udet al. (2007) analyzed 40 PICAs of 25 cadavers,\udlimiting their study to only two segments, i.e., the\udanteromedullary and the lateromedullary. In their\udresults, the relationships of the PICA with the cranial\udnerves are listed following the number of cranial\udnerve [‘‘(1) course of the LM segment of the PICA\udand its relationship to the facial and vestibular\udnerves; (2) relationship between the origin of the\udPICA and its course relative to the rootlets of the\udglossopharyngeal, vagus, and accessory nerves; (3)\udrelationship between the rootlets of the hypoglossal\udnerve and the PICA], rather than to the topographical\udcourse of the PICA, which would be clinically useful\ud(origin and relationship of the PICA and hypoglossal\udrootlets; lateromedullary segment of the PICA;\udrelationship between the PICA and the glossopharyngeal,\udvagus, and accessory nerves; tonsillomedullary\udand telovelotonsillary segments’ bifurcation). The\udformer way of presentation has led the authors to a\udmisinterpretation of the results of Macchi et al.\ud(2004). Indeed, Saylam et al. (2007) discuss that\udthe relationship of the PICA with the vagus nerve ‘‘is\udsomewhat variable’’ with respect to the patterns of\udthe course proposed by Macchi et al. (2004), who\udfound that if the artery originates at a caudal level, it\udtends to pass below the vagus nerve and that if it\udoriginates from the basilar artery (BA), it passes\udabove that nerve. In reality, the caudal level of the\udorigin of the PICA corresponds to the lateromedullary\udsegment of the vertebral artery (VA), and the data\udreported in Table 2 of the paper by Saylam et al.\ud(2007) makes it clear that when the PICA originates\udfrom the lateromedullary segment of the VA, it is\udlocated in all the cases (10/10) below the vagus\udnerve. Thus, the findings of Saylam et al. (2007),\udadding 10 further new cases, confirm our hypothesis\ud(Macchi et al., 2004). Moreover, Saylam et al.\ud(2007) report that they found only one PICA originating\udfrom the BA and passing between the IX and\udX cranial nerves, as shown in Figure 2; however, Figure\ud7 shows one more PICA originating from the BA,\udand passing above the IX cranial nerves. On the\udother hand, they did not consider it relevant to provide\udfigures of PICAs originating from the BA and\udpassing below the X cranial nerves.\udClinical-anatomic research is using computed tomography\udangiography (CTA) to map the vasculature\udin anatomical districts’ study (Tregaskiss et al.,\ud2007). Huynh-Le et al. (2004) reported that threedimensional\udCTA demonstrates the surgical anatomy\udof VA-PICA aneurysms in detail, and it is very useful\udin selecting the optimal surgical approach. Our team\udis evaluating the course of the PICA in vivo by computed\udtomography. From our anatomoradiological\uddatabase (Section of Radiology, Euganea Medica,\udItaly) six CTAs of the brain vessels (three males,\udthree females; mean age, 54.6 years) were selected.\udThe subjects underwent radiological examination for\udatherosclerotic pathology of the vessels of the circle\udof Willis. The CT images were obtained with a 16-\udslice multidetector CT scanner (Lightspeed16; GE\udMedical System, Milwaukee, WI) with the parameters\ud(group 1; rotation time, 0.7 sec; thickness, 2.5 mm;\udtable increment, 27/50; field of view, large; kV 140;\ud380 mA) acquired during the injection of the contrast\udmedium (concentration of 350 mg I/ml, Omnipaque,\udGE Healthcare, distributed by Amersham Health,\udPrinceton, NJ). A timing-bolus technique was applied\udto determine the delay time of scanning with a\udpreinjection of 20 ml of contrast media at a flow rateof 5 ml/sec. Subsequently, 90–100 ml were injected\udintravenously, at 5 ml/sec, followed by a 50-ml\udsaline chaser bolus, via a catheter placed in the\udcubital vein, and imaging acquisition was obtained in\udthe angiographic phase. The acquired data were\udthen reconstructed with 0.6-mm slice thickness with\udan overlapping of 0.3 mm. The data were transferred\udto an Aquarius workstation (TeraRecon TM, San\udMateo, CA), and three-dimensional reconstructions\ud(volume rendering technique, maximum intensity\udprojection, and multiplanar reconstructions) were\udobtained. We were able to visualize the PICA in\ud10/12 PICAs in CT images (Fig. 1), showing the site of\udorigin and the course of the lateromedullary segment.\udOur data confirm the role of CTA as advancing\udimaging technologies in basic anatomical research to\udstudy the vasculature both in cadaveric research and\udclinical studies in preoperative planning (Tregaskiss\udet al., 2007; Rozen et al., 2007)