Modified Head Fixation System for Intraoperative —

Hiroshi

CT Scanning

Technical

OKUDERA,

Shigeaki and

Note—

KOBAYASHI,

Kenichiro

Kazuhiko

KYOSHIMA

SUGITA*

Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Nagano; *Department of Neurosurgery, Nagoya University School of Medicine, Nagoya

Abstract A head

fixation

system

The

fixation

described. and

provides

Key words: stereotactic

using

artifact-free

open-field

carbon

was

images

instrumentation, method,

four

system

fiber

developed

during head

head

open-field

fixation,

pins

and

for intraoperative

modified

pin

computed

supporting tomographic

devices

is

scanning

neurosurgery. intraoperative

computed

tomography,

neurosurgery

Introduction The head fixation system is an important instrument in neurosurgery, especially in open-field neuro surgery.10) Many systems have been designed and used for safe, precise surgical procedures. i,2,s,6.s,9) Recently, intraoperative radiological diagnostic methods such as digital subtraction angiography and computed tomographic (CT) scanning have been in troduced into the operating theater .3,4,7)This requires improvement of the head fixation system to reduce imaging artifacts by using radiolucent materials. We use the CT scanner in our operating room,' and so have modified the ordinary head fixation system for intraoperative CT scanning. Modified

Head

Fixation

System

The head fixation system (head holder and pins9') was modified using an L-shaped head pin in a sup porting device on the head holder (Fig. 1). The reinforced carbon fiber head pin can be extended above the head holder and allows CT scanning with out artifacts (Fig. 2). The modified head fixation system allowed artifact-free CT images when used with the dry skull (Fig. 3 left), and in clinical intra Received

February

13, 1991;

Accepted

June

7, 1991

Fig. 1

Schematic drawings of the modified head fixation system. L-shaped head pin made of carbon fiber (a) and pin supporting device (b).

of the head pin, CT images using

successfully the ordinary

produced artifact-free head holder.

References 1)

2) 3)

Fig.

2

Modified

head

fixation

system

with

dry skull.

4)

5)

6)

7)

8)

Fig. 3 CT images with no artifacts using the modified head fixation system with dry skull (left) and in a clinical trial (right). 9)

operative CT scanning during removal of recurrent astrocytoma (Fig. 3 right). Discussion Our system was developed exclusively for intra operative CT scanning. Engle et al.3' developed a rigid ceramic head fixation device for intraoperative CT. However, their fixation system is too large for use with ordinary surgical instruments. Our modified fixation system, by changing the material and shape

10)

Aoki N, Sakai T: Modified application of three-point skull clamp for infants. Neurosurgery 25: 660-662, 1989 de Rougemont J, Barge M, Battalan L: Head fixation with bone hold. Neurochirurgie 17: 233-234, 1971 Engle DJ, Lunsford LD, Panichelli T: Rigid head fixation for intra-operative computed tomography. Neurosurgery 19: 258-262, 1986 Foley KT, Cahan LD, Hieshima GB: Intraoperative angiography using a portable digital subtraction unit. Technical note. J Neurosurg 64: 816-818, 1986 Kyoshima K, Kobayashi S, Sugita K: Fixation system for cervical spinal operation: Application of the head fixation system and multipurpose cervical frame. Neurosurgery 21: 591-594, 1987 Malawski S: A new version of a skull clamp of our design. Chir Narzadow Ruchu Ortop Pol 53: 412 415, 1988 Okudera H, Kobayashi S, Sugita K: Technical note: Mobile CT scanner gantry for use in the operating room. AJNR 12: 131-132, 1991 Rhea AH, Tranmer BI, Gross CE: Intraoperative cervical spine stabilization using the halo ring and the Mayfield three-pin skull clamp. Technical note. J Neurosurg 64: 157-158, 1986 Sugita K, Hirota T, Mizutani T, Mutsuga N, Shibuya M, Tsugane R: A newly designed multipurpose microneurosurgical head frame. Technical note. J Neurosurg 48: 656-657, 1978 Yasargil MG, Vise WM, Bader DC: Technical ad juncts in neurosurgery. Surg Neurol 8: 331-336, 1977

Address reprint requests to: H. Okudera, M.D., Depart ment of Neurosurgery, Shinshu University School of Medicine, Japan.

3-1-1

Asahi,

Matsumoto,

Nagano

390,