The document summarizes the authors' experience using the infratentorial supracerebellar approach in 23 patients with lesions located in the posterior third ventricle, quadrigeminal plate, culmen cerebelli, and cerebellar peduncle. Key findings include: - Three patients had transient worsening of deficits after surgery, and three developed postoperative hemorrhages requiring evacuation, with one death. - No complications could be unequivocally attributed to the surgical approach. - The authors concluded the approach allows safe access to the described lesion locations when combined with CSF drainage and the sitting position.

1. :Acta .
Neurochlrurgica
Acta Neurochir (Wien) (1992): 114:135 - I38
9 Springer-Verlag 1992
Printed in Austria
Experience with the Infratentorial Supracerebellar Approach in Lesions of the
Quadrigeminal Region, Posterior Third Ventricle, Culmen Cerebelli, and Cerebellar
Peduncle
G. Laborde 1, J. M. Gilsbach 1, A. Harders 1, and W. Seeger 2
Neurosurgical Department, Technical University of Aachen, and 2 Department of General Neurosurgery, University of Freiburg,
Federal Republic of Germany
Summary
supracerebellar-infratentorial
We report about our experience with the infratentorial supracerebellar approach in 23 patients operated on for lesions located
in the posterior part of the third ventricle, quadrigeminal plate,
culmen cerebelli and cerebellar peduncle.
Three patients had transient worsening of their deficits immediately after surgery. Three patients developed haemorrhages postoperatively requiring surgical evacuation. One of them died.
None of the patients developed specific complications which
could without any doubt be attributed to the approach. We concluded that in combination with intra-operative CSF drainage and
the sitting position the infratentorial supracerebellar approach allows
safe access to lesions situated in an area limited by the posterior part
of the third ventricle, the fastigium level and both cerebellar peduncles.
d e f i n e its limits.
Keywords: Infratentorial supracerebellar approach; quadrigeminal region; pineal tumour; third ventricle tumour.
Introduction
H o r s l e y 6 in 1910 a n d K r a u s e 9 in 1926 w e r e the first
to d e s c r i b e t h e s u p r a c e r e b e l l a r i n f r a t e n t o r i a l a p p r o a c h
for q u a d r i g e m i n a l lesions. O t h e r r o u t e s to the r e g i o n
o f t h e q u a d r i g e m i n a l p l a t e i n c l u d e the t r a n s c a l l o s a l
a p p r o a c h 1, t h e t r a n s v e n t r i c u l a r a p p r o a c h 26, a n d t h e
occipital transtentorial approach 4' 7, 10, 11, 15, 20, 24
U l t i m a t e l y , t h e q u e s t i o n o f w h i c h a p p r o a c h is u s e d
d e p e n d s o n the l o c a l i z a t i o n a n d e x t e n t o f the t u m o u r
a n d the i n d i v i d u a l c h o i c e o f the s u r g e o n . W e use the
supracerebellar-infratentorial
approach
to r e a c h tu-
m o u r s in t h e t e c t u m , in the p o s t e r i o r p a r t o f t h e 3rd
ventricle, in the d o r s a l a n d d o r s o l a t e r a l m i d b r a i n , in
the p i n e a l r e g i o n , a n d in t h e c u l m e n cerebelli.
T h e p u r p o s e o f this r e t r o s p e c t i v e s t u d y w a s to det e r m i n e w h i c h c o m p l i c a t i o n s c a n be a t t r i b u t e d to t h e
approach
itself a n d to
Patients and Methods
From 1979 to 1990, we operated on a total of 23 patients using
the supracerebellar infratentorial approach. The patients were 9 to
72 years of age (mean 36 years). Thirteen were females and nine
males.
Pre-operative stereotactic biopsy had been performed on eight
patients, since operability could not be conclusively determined by
CT and MRI. In the remaining 15 patients, surgery was performed
under the assumption of a technically operable benign lesion. One
patient had undergone pre-operative radiotherapy without confirmation of the histology by biopsy. The most frequent pre-operative
symptoms included signs of raised intracranial pressure (n-10),
ataxia (n = 4), and Parinaud syndrome (n = 3) in one patient with a
pineal germinoma and in two patients with epidermoids.
Eleven of the patients had had obstructive hydrocephalus prior
to surgery. In 10 of these patients a ventriculo-atrial shunt was
performed and in one case the tumour was directly approached.
Computer tomography and angiography were performed preoperatively in all cases; in five cases an MRI examination was carried
out.
The majority of tumours were located in the culmen cerebelli,
followed by lesions in the tectum and the pineal region (Table 1).
The patients were operated on in the sitting position. The head
was secured in a Mayfield skull clamp in AP position and bent
forward so that the direction of the straight sinus was parallel with
the horizontal plane (Fig. 1). Depending on the side of the lesion we
performed a unilateral or a midline osteoplastic suboccipital/occipital trepanation preceeded by a longitudinal incision.The upper
botmdary was about 1 cm above the transverse sinus, the lower one
about 2-3 cm below it. The dura was opened close to the lower
border of the sinus to prevent protrusion of the cerebellum (Fig. 1).
The upper edge of the incision was secured with stay sutures.
We always tried to reduce intracranial pressure by release of CSF
in order to facilitate the procedure above the culmen cerebelli or the
quadrangular lobe. If no hydrocephalus was present, a lumbar drain-

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G. Laborde et al.: Experience with the Infratentorial Supracerebellar Approach in Lesions
Table I. Location, Histology and Complications
Location
Pathology
Complications (No)
culmen cerebelli
2 astrocytoma (I, III)
1 haemangiopericytoma
1 medulloblastoma
1 metastasis
1 AVM
3 AVM
infection (1)
quadrigeminal region
pineal region
infection
haemorrhage *(2)
hydrocephalus (1)
1 haemangioblastoma
1 metastasis
1 falcotentorial meningioma
1 ependymoma 0II)
1 epidermoid
2 germinoma (IV)
1 pineocytoma (I)
1 dysplasic cyst
midbrain
2 cavernoma
1 metastasis
IIIrd. ventricle
2 teratoma
haemorrhage (1)
* Lethal.
age was inserted immediately before surgery or the cisterna magna
was punctured intra-operatively after trepanation. In patients with
an already existing shunt the valve was pumped or CSF aspirated
from the Rickham reservoir.
No ventricular drainage was performed intra-operativelf ~ 19,20.
~~
Fig. 1. Intra-operatively the patient's head is positioned in such a
way that the straight sinus is in a horizontal plane. Positioning and
location of the unilateral trepanation are schematically shown
Results
The diagnoses and histological findings are listed in
Table 1. With mild positive end-expiratory pressure,
haemostasis during jugular vein compression and precordial Doppler, no clinically significant air embolism
was observed. In three patients the occipital sinus had
to be severed, in 12 patients bridging veins between
vermis and tentorium or between q u a d r a n g u l a r lobe
and tentorium were severed.
I n two patients pre-existing neurological deficits
were more p r o n o u n c e d post-operatively than before
operation. One o f these patients had a t e r a t o m a in the
3rd ventricle and the second patient a medulloblastoma
in the culmen cerebelli. These two patients had an increased ataxia.
One patient with a dysplastic cyst developed postoperatively new but transient bilateral internuclear eye
m o v e m e n t disturbances worsened in p r o n e position,
associated with a severe intracranial hypotension syndrom, latent hemiparesis, ataxia and reduced short time
m e m o r y capacity.
Three other patients suffered post-operative haemorrhage. One o f them had an epidural h a e m a t o m a in

3. G. Laborde et al.. Experience with the Infratentorial Supracerebellar Approach in Lesions
the area of trepanation and two patients had haemorrhages in the operated area with intraventricular extension which had to be evacuated surgically. In one
of these patients the haemorrhage followed an operation for a cavernoma of the pons and midbrain. One
patient with an arterio-venous angioma in the area of
the quadrigeminal plate died of haemorrhage 5 hours
after surgical removal of the same.
One patient developed obstructive hydrocephalus
post-operatively, which was caused by local swelling
and had to be treated with a ventriculo-atrial shunt.
Three patients had a wound infection which required
wound revision with removal of the bone flap.
Discussion
The infratentorial supracerebellar approach provides access to an area ranging from the transverse
fissure to the fastigium level, laterally to the border of
the quadrigeminal plate and to the midline portion of
the upper cerebellar peduncle and posterior portion of
the 3rd ventricle 4' 13,22. This approach is not suited for
lesions located either in the brachium conjunctivum or
in the 4th ventricle below the fastigium level or for
those which spread extraventricularly into the thala15qUS.
We made no exceptions in requesting pre-operative
angiography as we felt it necessary in every case to
become familiar with the topography of the veins in
the vicinity of the tumour and to be able to rule out
any vessel malformation.
The intracranial decompression achieved by the use
of a pre-operative shunt facilitated the downward reclination of the cerebellum, however, it was associated
with a considerable risk (18.5%) of infection 3. In comparison Rappaport and Shalit ~6 had a 10% infection
rate when using peri-operative external ventricular
drainage in obstructive hydrocephalus caused by infratentorial tumours. It seems preferable to use that
method for treating the hydrocephalus, at least in patients with an assured postoperative normalization of
the CSF pathways and absorption.
Only in one patient was a shunt necessary in the
postoperative phase due to swelling of the midbrain
and the development of an obstructive hydrocephalus.
We preferred the sitting position for the operation
because of the associated low intravenous pressure and
the downward shift of the cerebellum after release of
CSF. Thereby good intra-operative vision without using retractors is provided for and less venous bleeding
occurs. The supine position, as recommended by
137
Kobayashi 8, can cause an increase in intracranial pressure and can hence bring about complications. We are
not in favour of the park bench position 24 because it
can obstruct the surgeon's movements. Careful occlusion of all the opened veins prevented the occurrence
of symptomatic air embolism, a complication which
induced Kobayashi 8 to use the same approach in patients in the supine position. In cases where it does
occur, it can be detected by Doppler sonography and
treated before a clinically relevant amount of air has
entered.
We performed a midline or unilateral osteoplastic
suboccipital/occipital trepanation. The site of the dura
opening was selected according to the localization of
the tumour. Both the approach above the quadrangular
lobe or the culmen cerebelli proved to be suitable for
reaching the quadrigeminal region. For lesions in the
fastigium or on the midline below the culmen level we
preferred the lateral approach.
In three patients the occipital sinus and in twelve
patients bridging veins had to be occluded and severed.
None of these measures resulted in any deficits 13.
Strict adherence to the indication for this approach
eliminates the necessity for incising the tentorium, since
in our patients the tentorium fold was large enough
for the resection of the tumour even above the tentorial
edge 18. In no case did Galen's vein, Rosenthal's veins
nor the internal cerebral veins present an obstacle. We
attribute this to the strict indication for this approach.
In no case did complications occur which could
unequivocally be attributed to this particular approach.
The postoperative increase in deficits in three patients must be attributed to the local manipulation in
the vicinity of the brainstem and not to lesions caused
by the approach. All surviving patients recovered completely with exception of one patient with a dysplastic
cyst who still has reduced short time memory capacity.
The aetiology of the eye movement disturbances she
developed is unknown. Heimburger 5 reported a similar
case of a patient presenting oculogyric crises occurring
when operated upon in the strictly supine position who
had a tumour located in the posterior third ventricle.
The 5% morbidity rate and the 2.5% mortality rate
are in accordance with the rates and causes given in
the literature 8' 12, 13, 14, 17, 21, 23 ranging from 0 to 30%
for mortality without morbidity. They are not related
to the approach. Using the supracerebellar infratentorial approach the cerebral structures are not damaged
compared with the transcallosal 1 or the transventricular approach 26. Nor is there any danger of harming

4. 138
G. Laborde et al.: Experience with the Infratentorial Supracerebellar Approach in Lesions
the occipital lobe as can occur with the transtentorial
route. This approach should be used in lesions located
mainly laterally and rostrally. The occipital-transtentorial approach is' 24 is not as well suited for access to
lesions located inferior to the aqueduct level, since it
requires dissection past Galen's vein.
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Correspondence and Reprints: Dr. G. Laborde, Neurosurgical
Department, Technical University of Aachen, PauwelsstraBe, D-W
5100 Aachen, Federal Republic of Germany.