Arteriovenous malformation grading system
Robert F. Spetzler
Robert F. Spetzler
✓ A new fixation technique for bone flaps is described. This technique avoids the use of hardware external to the skull in hairless areas where it may prove unsightly in patients with a thin scalp. The insertion of pins into the middle table of the skull firmly fixes bone flaps at one edge, eliminating the need for external plates at that site.
Robert F. Spetzler and Hartmut Spetzler
✓ A laboratory technique that allows strain measurements of the skull is described. Holographic interferometry allows the entire surface displacement of the skull to be mapped within 1/10 of the wavelength of light. Holographic interferometric pictures are presented following various stress applications to the skull. The method, besides being exquisitely sensitive, allows strain measurements simultaneously in any desired direction over the entire skull. No physical contact with the skull is required, and the experimental set-up is simple.
Leonardo Rangel-Castilla and Robert F. Spetzler
The ideal surgical approach to thalamic cavernous malformations (CMs) varies according to their location within the thalamus. To standardize surgical approaches, the authors have divided the thalamus into 6 different regions and matched them with the corresponding surgical approach.
The regions were defined as Region 1 (anteroinferior), Region 2 (medial), Region 3 (lateral), Region 4 (posterosuperior), Region 5 (lateral posteroinferior), and Region 6 (medial posteroinferior). The senior author’s surgical experience with 46 thalamic CMs was reviewed according to this classification. An orbitozygomatic approach was used for Region 1; anterior ipsilateral transcallosal for Region 2; anterior contralateral transcallosal for Region 3; posterior transcallosal for Region 4; parietooccipital transventricularfor Region 5; and supracerebellar-infratentorial for Region 6.
Region 3 was the most common location (17 [37%]). There were 5 CMs in Region 1 (11%), 9 in Region 2 (20%), 17 in Region 3 (37%), 3 in Region 4 (6%), 4 in Region 5 (9%), and 8 in Region 6 (17%). Complete resection was achieved in all patients except for 2, who required a second-stage operation. The mean follow-up period was 1.7 years (range 6 months-9 years). At the last clinical follow-up, 40 patients (87%) had an excellent or good outcome (modified Rankin Scale [mRS] scores 0–2) and 6 (13%) had poor outcome (mRS scores 3–4). Relative to their preoperative condition, 42 patients (91%) were unchanged or improved, and 4 (9%) were worse.
The authors have presented the largest series reported to date of surgically treated thalamic CMs, achieving excellent results using this methodology. In the authors’ experience, conceptually dividing the thalamus into 6 different regions aids in the selection of the ideal surgical approach fora specific region.
Robert F. Spetzler and Neil A. Martin
✓ An important factor in making a recommendation for treatment of a patient with arteriovenous malformation (AVM) is to estimate the risk of surgery for that patient. A simple, broadly applicable grading system that is designed to predict the risk of morbidity and mortality attending the operative treatment of specific AVM's is proposed. The lesion is graded on the basis of size, pattern of venous drainage, and neurological eloquence of adjacent brain. All AVM's fall into one of six grades. Grade I malformations are small, superficial, and located in non-eloquent cortex; Grade V lesions are large, deep, and situated in neurologically critical areas; and Grade VI lesions are essentially inoperable AVM's.
Retrospective application of this grading scheme to a series of surgically excised AVM's has demonstrated its correlation with the incidence of postoperative neurological complications. The application of a standardized grading scheme will enable a comparison of results between various clinical series and between different treatment techniques, and will assist in the process of management decision-making.
A. Giancarlo Vishteh and Robert F. Spetzler
Robert F. Spetzler and K. Stuart Lee
✓ Several techniques have been employed to incise the temporalis muscle for the pterional craniotomy. The authors describe a method which provides the advantage of a free bone flap, yet allows anatomical reapproximation of the temporalis muscle to its bone attachment.
Timothy Mapstone and Robert F. Spetzler
✓ A case is described in which vertebral artery occlusion, caused by a fibrous band, occurred whenever the patient turned his head to the right side, resulting in vertigo and syncope whenever the head was turned to the right. Release of a fibrous band crossing the vertebral artery 2 cm from its origin relieved the patient's vertebral artery constriction and symptoms.