Surgical Management and Outcomes of Aneurysms of Posterior Inferior Cerebellar Artery: Location-Based Approaches with Review of Literature

Background  Posterior inferior cerebellar artery (PICA) is a tortuous, variable, and uncommon site for aneurysms. Surgical management of PICA aneurysms involves careful selection of approach based on the location of the aneurysm and meticulous dissection of the neurovascular structures and perforators.

Materials and Methods  We did a retrospective review of all the PICA aneurysms operated at our institute in the past 10 years along with the site, presentation, and approach used for the same. Preoperative World Federation of Neurosurgical Society scores and follow-up modified Rankin scores (mRS) were also evaluated. During the same period, data for intervention cases of PICA aneurysm were also collected with follow-ups for a comparative analysis.

Results  A total of 20 patients with 21 PICA aneurysms were reviewed. All the reviewed cases presented with subarachnoid hemorrhage, and the most common location was the lateral medullary segment and vertebral artery (VA)–PICA junction. Midline approaches were used for distal PICA cases, with far-lateral approach reserved for anterior medullary/VA–PICA junction. No lower cranial nerve palsies were recorded at follow-up. Four cases needed cerebrospinal fluid diversion and two developed cerebellar infarcts. All cases were mRS 0 to 2 at follow-up.

Conclusion  Our series compares well with some of the larger surgical series of PICA aneurysms. This may be due to early referral patterns and early surgery (<24 hours) policy at our institution. Anatomical knowledge of PICA anatomy and sound perioperative management are keys to good outcomes in these cases.

One burr-hole craniotomy: Suboccipital midline approach to the fourth ventricle in Helsinki neurosurgery

Background:

In this video-abstract, we present one burr-hole craniotomy for the standard suboccipital midline approach developed in Helsinki neurosurgery for the microsurgical management of forth ventricle lesions, distal posterior inferior cerebellar artery aneurysms, and tumoral and vascular lesions of the vermis, cisterna magna region, and posterior brainstem as well.

Case Description:

We prefer to position the patient in sitting praying position. A midline straight single-layer incision starts on the inion and extends caudally toward the level of C2. The muscles are divided with diathermia along the occipital bone. Three curved retractors, two upward and one downward, provide a wide clean space for the craniotomy. Finger palpation and blunt dissection with cottonoids balls provide identification of the foramen magnum and the spinous process of C1. A burr-hole is made 1 cm lateral and below the level of the transverse sinus. After the detachment of the dura with a curved angled dissector, two cuts from both sites of the burr-hole are made with the craniotome. In case of an adherent dura particularly present in elderly patients, a long blunt flexible dissector (yasargil dissector) is used for the detachment of the bone from the dura. A craniotomy around the midline overlying the occipital sinus and the falx cerebelli is performed to expose medial aspects of cerebellar tonsils, the medulla oblongata, and the occipital sinus. Special care should be taken to avoid damaging the vertebral artery and the epidural sinuses running at the foramen magnum. A few drill holes are made for tack-up sutures. After a craniocervical-based opening of the dura, the fourth ventricle is accessed directly by telovelar route.

Conclusion:

The described one burr-hole craniotomy may represent the more efficient manner for performing the suboccipital midline approach to the fourth ventricle.

Videolink:

http://surgicalneurologyint.com/videogallery/suboccipital-midline-approach/

Lateral suboccipital retrosigmoid retrocondylar approach for foramen magnum meningiomas

Objective

The objective of the study was to describe our approach and the surgical technique and analyze its safety and the outcome for foramen magnum meningiomas (FMMs).

Methods

From 1986 to 2016, 15 FMM patients were operated on using the lateral suboccipital retrocondylar approach.

Results

In this series, there were 12 (80%) female and 3 (20%) male patients. The patients ranged in age from 33 to 63 years. There was no operative dead, but two patients died during the follow-up period, which varied from 1 to 24 years (mean, 10.2 years). Twelve patients (80%) achieved Glasgow Outcome Scale 4 or 5. Gross total resection was achieved in 13 (86.6.7%) patients.

Conclusions

The majority of FMM can be safely removed using the lateral suboccipital retrocondylar approach without condylar resection, associated to meticulous microsurgical technique.

Versatility of sub-occipital approach for foramen magnum meningiomas: a single centre experience

BACKGROUND

Foramen magnum meningiomas (FMM) represent a challenge for neurosurgeons. Multiple surgical strategies have been reported to treat these lesions in their variable location. Contemporary technical innovations allow the utilization of common sub-occipital craniotomy to treat ventrally, ventro-laterally and dorsally located FMMs. We present our technique and experience.

METHODS

From November 2004 to November 2015, we treated 14 patients with FMM at the Department of Neurosurgery of the Santa Maria delle Grazie Hospital in Pozzuoli, Naples, Italy. There were 10 females and 4 males, with a mean age of 64.5 years (range, 55-77 years). All patients had high field magnetic resonance imaging (MRI) with contrast enhancement preoperatively, which led to the radiological diagnosis. A sub-occipital craniotomy was performed in all patients as well as the removal of the posterior arch of C1. Partial removal of C2 was necessary in 2 patients. Neck pain was the most common symptom of presentation. Paraparesis was present in patients in 3 patients. Upper limbs dysesthesia or pain existed in 3 cases.

RESULTS

Thirty days after surgery neck pain and dysesthesia decreased in all patients affected. Neurological improvement was observed in 2 patients affected by weakness in lower limbs at 6 months follow up. Paraparesis was unchanged in 1 patient. Two patients presented transient worsening after surgery. Transient dysphagia occurred in one case and postoperative hemorrhage with subsequent surgery in another patient. We had no postoperative mortality.

CONCLUSIONS

FMM surgery should be tailored to the lesion at hand as in most instances it is possible to avoid the use of extensive skull base approaches.

The suboccipital ligament

OBJECTIVE A fibrous structure located dorsal to the dura at the posterior craniocervical junction stretches horizontally between the bilateral occipital condyles and the upper borders of the C-1 laminae. Partially covered by the occipital bone, this structure is always encountered when the bone is removed from the foramen magnum rim during approaches to the posterior cranial fossa. Although known to surgeons, this structure has not been defined, studied, or named. The most appropriate name for this structure is "the suboccipital ligament," and a detailed rationale for this name is provided. METHODS This 3-year-long study included 10 cadaveric specimens and 39 clinical patients: 31 consecutive surgically treated patients with Chiari Type I malformations (CM-I subgroup) and 8 other patients with posterior fossa pathologies (non-CM-I subgroup). The dimensions were defined, the function of this ligament was hypothesized, size and histological composition were compared between patient subgroups, and its origin and relationship to the surrounding structures were analyzed. Possible statistical differences in the parameters between the 2 groups were also evaluated. RESULTS The suboccipital ligament consists of horizontally oriented hyaline fibers and has a median length of 35 mm, height of 10 mm, and thickness of 0.5 mm. These dimensions are not significantly different between the CM-I and non-CM-I patients. The median age of the patients was 43 years, with CM-I patients being significantly younger (median 35 years) than non-CM-I patients (median 57 years). There was no statistically significant difference in weight, height, and body mass index between patient subgroups. There was no significant correlation between the body mass index or height of the patients and the dimensions of the ligament. No statistically significant differences existed between the subgroups in terms of smoking history, alcohol consumption, and the presence of diabetes mellitus, hypertension, hydrocephalus, or headaches. The ligament tissue in the CM-I patients was disorganized with poorly arranged collagen bands and interspersed adipose tissue. These patients also had more hyalinized fibrosis and showed changes in the direction of fibers, with hyaline nodules ranging from 0 to 2+. The result of the histological evaluation of the suboccipital ligament for hyaline nodules, calcification, and ossification was graded as 2+ if present in 3 or more medium-power magnification fields (MPFs); 1+ if present in 1-2 MPFs; and 0, if present in less than 1 MPF. Histological examination of the ligaments showed structural differences between CM-I and non-CM-I patients, most notably the presence of hyaline nodules and an altered fiber orientation in CM-I patients. CONCLUSIONS The suboccipital ligament extends between the occipital condyle and the superior edge of the C-1 lamina, connecting the contralateral sides, and appears to function as a real ligament. It is ventral to the occipital bone, which covers approximately two-thirds of the height of the ligament and is loosely attached to the dura medially and more firmly laterally. Because of its distinctive anatomy, characteristics, and function, the suboccipital ligament deserves its own uniform designation and name.

Suboccipital osteoblastoma: Microsurgical resection of a rare entity

BACKGROUND

Osteoblastomas are rare lesions comprising 1% of all bone tumors. The occipital bone is one of the rarest affected bone, with only 11 cases reported during the last 40 years.

CASE DESCRIPTION

Here, we describe the clinical presentation and the radiological features of a suboccipital osteoblastoma that was successfully resected in a 30-year-old man. A short video shows the microsurgical removal of the lesion. There was no recurrence during a 12-month follow-up.

CONCLUSIONS

Even if osteoblastomas are benign tumors, a complete removal has to be achieved to reduce the risk of recurrences. This makes necessary an appropriate monitoring of the patient.