Federica Beretta

Exposure of the cervical internal carotid artery: surgical steps to the cranial base and morphometric study.

OBJECTIVE: Several studies have reported on approaches to increase exposure of the distal cervical internal carotid artery (ICA), but these studies have neither systematically addressed the anatomic aspects nor quantified the additional exposure of each maneuver. We describe surgical steps to expose the ICA region, quantify the additional exposure of each operative step, and discuss ways to minimize surgical morbidity. METHODS: The ICA was exposed in 10 formalin-fixed cadaveric heads using the following four steps: 1) anterior sternocleidomastoid approach, 2) retroparotid dissection and division of the digastric muscle, 3) section of the styloid apparatus, and 4) mandibulotomy. After completion of each step, the most distal level of ICA exposure was marked with a hemoclip and segment lengths were measured between each clip. RESULTS: Sectioning of the digastric muscle and sectioning of the styloid apparatus provided the most significant exposure of the ICA (14.15 and 15.08 mm, respectively) with minimal risks. Mandibulotomy added 10.20 mm in length and 20.65 degrees in width, but is a maneuver that must be weighed against the heightened risk of morbidity. CONCLUSION: Surgical exposure of the distal cervical ICA is associated with relatively high morbidity that increases with higher levels of exposure. Staged maneuvers have been shown to increase ICA exposure, especially in our systematic approach. The number of steps required varies depending on the level of lesion. Complete understanding of the surgical anatomy is essential to minimize surgical morbidity and to develop surgical expertise.

Evidence for the improved exposure of the ophthalmic segment of the internal carotid artery after anterior clinoidectomy: morphometric analysis

SummaryBackground. Although resection of the anterior clinoid process (ACP) is valuable in the surgical treatment of aneurysms of the ophthalmic (C6) segment of the internal carotid artery (ICA), quantitative assessment of this adjunct is incomplete. Our morphometric study assesses the effectiveness of the anterior clinoidectomy for exposure of the C6 segment of the ICA.Methods. Ten formalin-fixed adult cadaveric heads were dissected bilaterally and pterional craniotomies were performed bilaterally. Measurements before and after resection of the ACP included the length of C6 segment of the ICA on its lateral aspect; C6 segment length on its medial aspect; and medial length of the optic nerve from the optic chiasm to falciform ligament (before ACP resection) then to the annulus of Zinn (after ACP resection).Findings. Height and width of the intradural ACP were 8.67 ± 2.63 and 6.57 ± 1.68 mm, respectively. After clinoidectomy, mean length of the lateral C6 segment of the ICA increased 60% and mean exposure of the medial C6 segment of the ICA increased 113% (p < 0.001). Exposure of the optic nerve increased 150% (p < 0.001) after clinoidectomy and sectioning of the falciform ligament. No correlations were found between the lengths of the ACP and entire C6 segment, or the ACP size and amount of the C6 segment covered by the clinoid.Conclusions. Exposure of the C6 segment of the ICA is markedly increased by increase of the mobility of the optic nerve with clinoidectomy and section of the falciform ligament.

Aneurysms of the Ophthalmic (C6) Segment of the Internal Carotid Artery: Clinical Experience, Treatment Options, and Strategies (Part 2)

Treatment of ophthalmic (C6) segment aneurysms continues to be challenging and technically demanding for neurosurgeons, resulting in high rates of morbidity and mortality. In part 2, we provide a contemporary review of recent clinical series and assess the advantages and limitations of surgical and endovascular treatments relative to published series as well as our own. In part 1, we detailed the key embryologic, anatomical, and radiologic points that now provide the foundation for our critical discussion of such management strategies. We report the results of our 78 patients with 88 C6 segment aneurysms, including 43 with unruptured aneurysms and 35 with subarachnoid hemorrhage (SAH), 9 of which were giant and 25 of which were large. Management strategies included surgical clipping alone in 53 patients, clipping and hemicraniectomy in 2, coiling in 17, extracranial-to-intracranial bypass in 2, and coil occlusion of the internal carotid artery in 2. Of 2 patients who underwent no treatment, 1 had a myocardial infarction after diagnostic angiography and 1 declined treatment. Overall mortality was 6.4% (5 patients with SAH). At discharge, Glasgow Outcome Scale (GOS) scores were good (GOS score of 1 or 2) in 63 (80.8%) patients and poor (GOS score of 3 or 4) in 10 (12.8%) patients. In this review, we describe how the synergistic use of surgical and endovascular procedures seems to offer the best approach to these aneurysms to minimize morbidity associated with treatment and to achieve outstanding outcomes, highlighting the treatment strategies used by the senior surgeon.

Anterior spinal pseudomeningocele after C0–C2 traumatic injuries: role of the “dural transitional zone” in the etiopathogenesis

PurposeSpinal pseudomeningoceles (SPM) are extradural collections of CSF (cerebrospinal fluid); a frequent association with upper cervical injuries (UCI) has been observed. We propose a possible etiopathogenetic mechanism supporting the formation of cervical SPM based on some considerations.MethodsWe present four cases of SPM. All patients sustained a severe UCI. Three patients were symptomatic with delayed and progressive clinical signs.ResultsOne patient was misinterpreted as epidural hematoma and operated on due to progressive signs with postoperative clinical improvement. The rest of patients were treated conservatively; spontaneous reduction of CSF collection occurred. From a radiological standpoint: (1) a line of demarcation separated the intradural cervical compartment from the anterior epidural space, (2) CSF epidural collection was never evident at C0–C2 level and extended from C2 downwards, and (3) shape of collection was similar to epidural hematomas suggesting a ball-valve mechanism.ConclusionsThe dural layer at C0–C2 level is adherent to the thick ligamentous apparatus, as opposed to the segments below where it is solely covered by the posterior longitudinal ligament. A “transitional zone” of dura exists between the C0–C2 region and subaxial segment of the cervical spine. This watershed area constitutes a point of minor resistance. Lacerations of the meningeal layers, caused by severe UCI at the “transitional zone”, drain CSF into the anterior epidural space and form SPM.

Surgical Indications and Treatment for Cranial Occipital Anomalies

Occipital anomalies (in particular flattening) may be related to several conditions including craniosynostosis. In general, there are three main groups of occipital flattening: 1) positional plagiocephaly, 2) lambdoid craniosynostosis, and 3) alterations related to other conditions (i.e. other types of craniosynostosis, cervical malformations, and so forth). Proper differential diagnosis is mandatory. Physical examination often allows the diagnosis, but there may be cases requiring radiological assessments.Positional forms are the most common and usually need no surgical correction, even though severe deformities that persist beyond the year of age may require surgery. Lambdoid craniosynostoses are quite rare and do require surgical correction. Different operative techniques have been proposed, but the intervention usually consists of a posterior cranial expansion. Occipital anomalies related to other conditions usually require a tailored treatment addressed to manage the alterations responsible for the deformity.

Aneurysms of the Ophthalmic (c6) Segment of the Internal Carotid Artery: Embryology, Surgical Anatomy, and Radiology (part 1)

Aneurysms arising from the intradural ophthalmic (C6) segment of the internal carotid artery (ICA) constitute 5% to 11% of all intracranial aneurysms; 25% of these aneurysms are giant, and 50% are multiple. Critical to the successful treatment of these aneurysms is an understanding of the embryologic development, regional anatomy, and radiographic techniques. In part 1 of this review, we discuss theories of Dorcas Hager Padget (neuroembryologist and neurosurgical illustrator) and Pierre Lasjaunias to clarify the complex embryology of this cerebral vasculature and to identify the vascular anomalies of the C6 segment. Next, we provide comprehensive detail of the bone, connective tissue, and vascular structures that are intimately related in the confining space surrounding the distal dural ring (DDR) and anterior clinoid process. The anatomic complexity of the region surrounding the C6 segment of the ICA partly explains the surgical challenge in treating aneurysms of this segment and the relatively high incidence of postoperative complications. We review the radiologic techniques to assess these aneurysms when planning treatment, such as the role of cerebral angiography in providing details about the hemodynamic function of the vessels (eg, collateral circulation pattern, potential recipient vessels for bypass) and the role of the DDR in distinguishing aneurysms of the extradural or intradural segment of the ICA. Although these aneurysms remain challenging, the information reviewed in part 1 helps to understand these aneurysms more clearly in terms of embryology, anatomy, and radiology for successful treatment strategies. Applications of this information are discussed in part 2, in which we review clinical experience and treatment strategies.