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Supracerebellar Infratentorial Approach to Brainstem Cavernous Malformations
Jean G. de Oliveira, Gregory P. Lekovic, Sam Safavi-Abbasi, Cassius V.C. Reis, Ricardo A. Hanel,
Randall W. Porter, Mark C. Preul, Robert F. Spetzler
Division of Neurological Surgery, Barrow Neurological Institute
St. Joseph’s Hospital and Medical Center, Phoenix-AZ.
Introduction
Methods
The supracerebellar infratentorial (SCIT) approach can
be performed at the midline (median variant), lateral to
the midline (paramedian variant), or at the level of the
angle formed by the transverse and sigmoid sinuses
(extreme lateral variant). We analyzed our experience
with SCIT approaches for the surgical treatment of
cavernous malformations of the brainstem (CMBs).
Demographic, clinical, radiological and surgical data
from 45 patients (20 males and 25 females; mean age,
36.2 years) with CMBs surgically removed through SCIT
approaches were reviewed retrospectively: 23 lesions
were in the midbrain, 3 were at the midbrain and
extended to the thalamus, 9 were at the
pontomesencephalic junction, and 10 were in the upper
pons.
Results
Figure 1. Application of the two-point method. The best trajectories for the (A)
median SCIT approach, (B) paramedian SCIT approach, and (C) extreme lateral
SCIT approach. Used with permission from Barrow Neurological Institute.
Figure 3. Paramedian variant of the SCIT approach. (A) Patient’s position and
skin incision (dashed line). (B) Craniotomy and dural opening (dashed line). (C)
Area of exposure (shaded). (D) Microsurgical view of the anatomy in a cadaveric
specimen (IC: inferior colliculus; P.C.A.: posterior cerebral artery; Pi: pineal;
S.C.A.: superior cerebellar artery; SC: superior colliculus; Tent.: tentorium
All patients presented with hemorrhage. The median
variant was used in 13 patients, the paramedian variant
in 9, and the extreme lateral variant in 23.
Intraoperatively, all CMBs were associated with a
developmental venous anomaly (DVA). At last follow-up,
88% of the patients were the same or better. After a
mean follow-up of 20 months, their mean Glasgow
Outcome Scale score was 4.1.
Illustrative Case. A 63-year-old woman presented with left-sided numbness,
double vision, dysphagia, gait ataxia, and dizziness. Preoperative (A) sagittal T1weighted, (B) axial T1-weighted, and (C) T2-weighted MR images showing a
CMBs abutting at the posterior incisural space. The extreme lateral variant of
the SCIT was recommended based on the best trajectory determined by the
two-point method. Postoperative (D) sagittal T1-weighted, (E) axial T1weighted, andConclusions
Conclusions
SCIT approaches provide excellent exposure to CMBs
located at the posterior incisural space not only in the
midline but also in the posterolateral surface of the
upper pons and midbrain. Careful preoperative planning
and neuronavigational assistance are needed to
determine the best angle of attack and trajectory for
SCIT approaches. Refined microsurgical techniques are
paramount to achieve safe surgical removal of CMBs
with good outcomes.
Figure 2. Median variant of the SCIT approach. (A) Patient’s position an d skin
incision (dashed line). (B) Craniotomy and dural opening (dashed line). (C) Area
of exposure (shaded). (D) Microsurgical view of the anatomy in a cadaveric
specimen (3rd Vent.: third ventricle; IC: inferior colliculus; M.P.Ch. A.: medial
posterior choroidal artery; P.C.A.: posterior cerebral artery; Pi: pineal; S.C.A.:
superior cerebellar artery; SC: superior collic Tent.: tentorium).
Figure 4. Extreme lateral variant of the SCIT approach. (A) Patient’s position and
skin incision (dashed line). (B) Craniotomy and dural opening (dashed line). (C)
Area of exposure. (D) Microsurgical view of the anatomy in a cadaveric
specimen (CN IV: fourth cranial nerve; CN V: fifth cranial nerve; IC: inferior
colliculus; P.C.A.: posterior cerebral artery; Pet. V.: petrosal vein; S.C.A.:
superior cerebellar artery; SC: superior colliculus; Tent.: tentorium).
Figure 5. A: Intraoperative view guided by neuronavigation. B: Superficial aspect
of the brainstem. C and D: Microsurgical aspect of the CMBs.