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The Use of Bony Landmarks of the Skull for Localization of the Anterior-Posterior Commissural Line

1965; American Association of Neurological Surgeons; Volume: 22; Issue: 6 Linguagem: Inglês

10.3171/jns.1965.22.6.0576

1933-0693

Ralph F. Kamm, George Austin,

Fetal and Pediatric Neurological Disorders

T HE procedure of ventrolateral thalam o t o m y is being widely used in the t r ea tmen t of ext rapyramidal disorders. In most neurosurgieal centers, the method of locating the t a r g e t nucleus involves air encephalography. There are m a n y reasons why it would be desirable to eliminate the instillation of air f rom the procedure: 1) the potential danger for the pat ient (especially in view of the known electrocardiographic changes 1 and the advanced age of m a n y of the pat ients) ; 2) the damping of the involuntary m o v e m e n t s often observed following the instillation of air; 3) the decreased level of awareness of the pa t i en t -who is later asked to repor t experiences during st imulation; 4) the vagaries of filling the ventr icular sys tem and the occasional technical difficulties in performing the air s tudy; 5) the lengthening of the to ta l procedure; and 6) the variable, but always present, absorpt ion of p a r t of the air during the procedure. Despi te these disadvantages, ventr icular air is used a lmost universally. The basic reason for this is related to the variabil i ty of the human skull and the inconstancy of a readily visualized pineal body. Because of this variabil i ty, a t t emp t s to use bony landmarks in stereotaxic procedures have been almost abandoned and most of the work in the field of s tereoencephalotomy has been in the refining of methods using intraventr icular air or occasionally Thorotras t . The purpose of the present s tudy is to define some bony landmarks which have been used successfully together with careful physiological tes t ing of responses to st imula-