Sven O. Eicker, Klaus Christian Mende, Lasse Dührsen and Nils Ole Schmidt
The surgical management of lesions ventral to the neuraxis at the level of the craniovertebral junction (CVJ) and upper cervical spine is challenging. Here, the authors describe a minimally invasive dorsal approach for small ventrally located intradural lesions at the CVJ as an alternative for the more extensive classic transoral approach or variants of suboccipital approaches.
Between 2012 and 2014, 6 symptomatic patients with a small lesion of the ventral aspect at the CVJ level were treated using a minimally invasive dorsal approach at the University Medical Center in Hamburg-Eppendorf, Germany. The anatomical distance between the posterior atlantooccipital membrane and the posterior atlantoaxial ligament, as determined by CT images, was assessed in the treated patients and in 100 untreated persons.
The authors treated 6 patients (mean age 54.7 years) who had a clinical presentation of mild neurological symptoms that disappeared after resection. Minimally invasive surgical dorsal access was achieved by using tubular systems and using the natural space between the occiput (C-0) and C-1, and in 1 case between C-1 and C-2, without having to remove bony structures. The postoperative course in each of the 6 patients was uneventful. The neuropatho-logical findings confirmed a meningotheliomatous meningioma (WHO Grade I) in 5 cases and an extramedullary cavernous hemangioma in 1 case. MRI confirmed complete resection of all the lesions. The atlantooccipital distances ranged from 3 to 17 mm (mean 8.98 mm) in the supine neutral position, and the atlantoaxial distances ranged from 5 to 17 mm (mean 10.56 mm). There were no significant differences between women and men (atlantooccipital p = 0.14; atlantoaxial p = 0.72).
The results of this study demonstrate that the minimally invasive dorsal approach using the space between C-0 and C-1 or C-1 and C-2 provides direct and sufficient exposure for the safe surgical resection of small ventrally located intradural lesions at the CVJ level while reducing the necessity for musculoskeletal preparation to a minimum.
Pavlina Lenga, Christian Hohaus, Bujung Hong, Adisa Kursumovic, Nicolai Maldaner, Jan-Karl Burkhardt, Philippe Bijlenga, Daniel A. Rüfenacht, Nils O. Schmidt, Peter Vajkoczy and Julius Dengler
Giant posterior circulation aneurysms (GPCirAs) usually cause substantial mass effect on the brainstem, which may lead to neurological deficits. So far, there has been no systematic investigation of factors associated with such deficits in GPCirA. The authors aim to examine the risk factors for cranial nerve deficit (CND), motor deficit, and disability in patients with GPCirA.
Using MR images obtained in 30 patients with unruptured GPCirA, the authors examined GPCirA volume, presence of hydrocephalus or partial thrombosis (PT) of the aneurysm, and the degree of brainstem displacement measured by the distance between the McRae line and the tip of the GPCirA (∆MT). They evaluated associations between these factors and neurological deficits.
Thirty GPCirAs in 30 patients were included. The prevalence of CNDs was 50%. Patients with CNDs significantly differed from those without CNDs in terms of age (mean 51.0 years [SD 15.0 years] vs 69.0 years [SD 21.0 years], p = 0.01) and in ∆MT (median 50.7 mm [IQR 39.2–53.9 mm] vs 39.0 mm [IQR 32.3–45.9 mm], p = 0.02). The prevalence of motor deficits was 33.3%. Patients with motor deficits showed a larger ∆MT (median 50.5 mm [IQR 40.8–54.6 mm]) compared with those without (∆MT: median 39.1 mm [IQR 32.8–50.5 mm], p = 0.04). GPCirA volume was larger in patients with poor modified Rankin Scale (mRS) scores (median 14.9 cm3 [IQR 8.6–18.7 cm3]) than in those with mRS scores of 0–2 (median 6.8 cm3 [IQR 4.4–11.7 cm3], p = 0.03). After adjusting for patient age and the occurrence of hydrocephalus or PT, the authors found that higher degrees of disability were significantly associated with aneurysm volume (OR 1.13, 95% CI 1.0–1.3; p = 0.04), but not with ∆MT. The occurrence of CND or motor deficit was not associated with any of the examined variables. There was no correlation between GPCirA volume and ∆MT (rs = 0.01, p = 0.96). The prevalence of neurological deficits did not differ between GPCirA at the basilar apex, the basilar trunk, the vertebrobasilar junction, or the vertebral artery.
In this study, the neurological condition of the patients was associated only with GPCirA volume and not with the degree of brainstem displacement, the occurrence of PT or hydrocephalus, or the exact location of the GPCirA. These findings highlight the clinical relevance of GPCirA volume and suggest that factors such as brainstem displacement or PT should play less of a role when finding arguments for or against treatment of GPCirA.
Clinical trial registration no.: NCT02066493 (clinicaltrials.gov)