66 Surgical Positioning and Exposures

Closure 1.112 The skin is closed with
metal clips. A sterile noncompression
dressing is applied to the operative site.

67

Lateral Oblique: Lower Lateral Suboccipital Approach

1.113

Lower Lateral Suboccipital Approach

The lower lateral Suboccipital ap-
proach gives access to the cerebellar hemi-
sphere, tonsillar region, and craniocervical
junction. The vertebral artery from dural
entry to the vertebrobasilar junction and
the anterolateral brainstem are also
accessible.

1.113 For a lower lateral sub-
occipital approach, the patient is placed in
the lateral oblique position. The thorax is
elevated 15 degrees and the head is in neu-
tral flexion.

1.114 The patient's head is
maintained in 0 degrees rotation. A lateral
hemispheric (hockey-stick) incision is used.

1.114

Surgical Positioning and Exposures

1.115

1.115 The lateral hemispheric
(hockey-stick) incision begins over the
mastoid, ascends across the superior nu-
chal line, and descends in the midline of the
cervical spine. The craniotomy consists of
cutting a suboccipital bone flap (3x4 cm),
opening the foramen magnum, and per-
forming a laminectomy of the laminar arch
of Cl. Partial resection of the medial one
third of the occipital condyle is optional.

1.116 The skin is incised and
hemostatic clips are placed on the skin
edges. The cutaneous flap is developed to
gain myofascial exposure.

1.116

69

Lateral Oblique: Lower Lateral Suboccipital Approach

Superior nuchal
line

1.117, 1.118 The myofascial flap is
incised just below the superior nuchal line.
A superior cuff remains for subsequent clo-
sure. The cervical muscles are opened in
the avascular midline plane down to the
periosteum of the occipital bone and lami-
nar arches of Cl and C2.

1.118

78 Surgical Positioning and Exposures

\ ., Occipital
condyle

1.119

1.120

1.119 A single-entry burr hole
is made 1 cm medial and inferior to the
asterion. A free bone flap (3x4 cm) is cut
in the occipital bone with a pneumatic
craniotome.

1.120 The foramen magnum is
opened with a rongeur.

71

Lateral Oblique: Lower Lateral Suboccipital Approach

Vertebral
artery

1.121 The laminar arch of Cl
is removed with a rongeur. The extradural
horizontal segment of the vertebral artery is
mobilized out of the vertebral groove on Cl
so that the lateral laminar arch can be re-
moved safely up to the pedicle.

1.122 For approaches that re-
quire extreme lateral exposure to access
the lateral and anterior brainstem, the sur-
geon can resect additional occipital bone,
the medial one third of the occipital con-
dyle, and the lateral mass of Cl. However,
this maneuver is time-consuming, requires
dissection of the basilar venous plexus, and
is unnecessary in many cases.

Occipital
condyle

Lateral mass
ofC1

Vertebral
artery

1.122

72 Surgical Positioning and Exposures

1.123

1.123 The dural incision be-
gins at Cl, extends vertically through the
foramen magnum, and proceeds laterally to
the superolateral apex of the craniotomy.

1.124 The posterior fossa and
spinal dura are reflected laterally with dural
retention sutures. An incision begins in the
spinal arachnoid and proceeds through the
cisterna magna while cerebrospinal fluid is
aspirated.

1.124

Lateral Oblique: Lower Lateral Suboccipital Approach 73

1.126

Closure 1.125 The dura is closed with
absorbable sutures.

1.126 The bone flap is secured
with stainless steel wires. The cervical
muscles are firmly reattached to the supe-
rior myofascial cuff. The cervical muscles
and fascia are closed in layers.

1.127 The occipital galea and
cervical subcutaneous fascia are closed
with absorbable sutures. The skin is closed
with metal clips. A sterile noncompression
dressing is applied to the operative site.

74 Surgical Positioning and Exposures

1.128

Bilateral Suboccipital Approach

The bilateral suboccipital approach
gives exposure from the pineal region
through the foramen magnum and into the
upper cervical spine. Access is also pro-
vided to both cerebellar hemispheres,
the vermis, fourth ventricle, and dorsal
brainstem.

1.128 For a bilateral suboc-
cipital approach the patient is placed in the
lateral oblique position. The thorax is ele-
vated 15 degrees and the head is in a flexed
position.

1.129 The head is maintained
in 0 degrees rotation. A midline linear inci-
sion is used.

1.129

Lateral Oblique: Bilateral Suboccipital Approach 75

1.130

1.130 A linear incision ex-
tends from the spinous process of C6 to
2 cm above the inion. The craniotomy
(3x6 cm) is centered on the midline.

1.131 The skin is incised in
the midline; bilateral cutaneous flaps are
developed at least 3 cm to either side of the
midline at the superior nuchal line. Hemo-
static clips are applied to the skin edges. A
superior myofascial cuff is developed by
transverse incision of the cervical muscles
just below the superior nuchal line. The
cervical muscles are opened in the avascu-
lar midline down to the periosteum of the
occipital bone and laminae of Cl and C2.

1.131

76 Surgical Positioning and Exposures

Inion

Superior

facial

cuff

1.132 Two pairs of entry burr
holes are made lateral to the midline below
the inion and above the foramen magnum.
Free bone flaps are cut on both sides of the
midline with a pneumatic craniotome.

1.133 The bone is cut from
each lower burr hole into the foramen mag-
num. The upper burr holes are connected
by cutting a groove in the occipital bone.
The midline free bone flap is fractured with
a periosteal elevator and removed.

Lateral Oblique: Bilateral Suboccipital Approach 77

1.134

1.134 The foramen magnum is
opened widely by further removal of occipi-
tal bone with a rongeur. The Y-shaped dural
incision begins in the midline of the fora-
men magnum and extends superiorly to de-
velop three flaps.

1.135 The dural flaps are re-
tracted superiorly and laterally with dural
retention sutures. Ten-millimeter self-re-
taining retractors are applied to gently sep-
arate both cerebellar tonsils. The arachnoid
of the cisterna magna is incised in the mid-
line as cerebrospinal fluid is aspirated.

1.135

78 Surgical Positioning and Exposures

1.136

Closure 1.136 The dura is closed with
absorbable sutures. The bone flaps are
fixed in position with stainless steel wires
through drill holes. The ends of the wires
are tucked into the drill holes. The cervical
muscles are firmly reattached to the supe-
rior myofascial cuff; cervical muscles and
fascia are closed in multiple layers. After
the skin is closed with metal clips, a sterile
noncompression dressing is applied to the
operative site.

---