Postgraduate Medical Journal (December 1973) 49, 960-864.

Stereotactic limbic leucotomy: surgical technique

ALAN RICHARDSONF.R.C.S.

Department of Neurosurgery, St George's Hospital atAtkinson Morley's Hospital, Wimbledon, SW20 ONE

SummaryThe requirements for modern psychosurgery aresafety and accuracy.

Stereotactic techniques give the geometric accuracyand stimulation gives physiological information, whichis important in determining lesion sites or at leastlesion symmetry.The process whereby focal brain destruction is

produced is ideally by a freezing probe, but equallyeffectively by coagulation. A number of small lesionsis thus required. This at present is unavoidable if sideeffects are to be obviated. Careful continuing assess-ment of results is necessary to validate any surgicalprocedure.

THE basic neuro-anatomical and neuro-physiologicalconcepts in relation to leucotomy for the treatmentof mental illness have advanced over the last 20years. This has been correllated with early surgicalexperience and has led to the modern approach topsychosurgery. The frontal lobes were the traditionalsites for surgical interference in the majority ofprocedures, but a clear understanding of the rela-tionships of the medial and orbital surfaces of thefrontal lobe to the limbic system has not only modi-fied views regarding the appropriate sites for lesionmaking but also helped to define more accuratelythe extent of the necessary procedures.As Livingston (1969) has pointed out 'we can

visualize a great fronto-limbic-hypothalamic-mid-brain behavioural axis in which two somewhat paral-lel circuits of activity stand out. The medial frontal-cingulate-hippocampal and the other the orbitalfrontal-temporal-amygdalar, both playing down onthe hypothalamus and brain stem. The medialfrontal-cingulate-hippocampal circuit is closed viafornix-mamillary-anteriorthalamic-frontal connec-tions, while the orbital frontal-temporal-amyg-dalar circuit is closed via amygdalar-dorsomedial-thalamic-frontal connections.' It must not be as-sumed, however, that these circuits are discrete, forNauta (1962) has made the point that their efferentconducting systems are quite comparable, suggestingthat they may form part of a massive linked system.The interrelationships of the frontal lobe to the

limbic system was taken further by Nauta (1971)when he suggested that the frontal lobe both modu-lated and monitored limbic activity. Lewin (1961)viewed the medial limbic circuit as a potential rever-berating system to explain the beneficial effect ofcingulectomy on obsessional states. Finally, onemight propose that the medial and perhaps orbitalsurfaces of the frontal lobe may be played upon byany disturbance in a reverberating limbic circuit andin the words of Papez (1937) 'add emotional colour-ing to the psychic process'.These rather simple, and perhaps oversimplified,

considerations form the basis of our current surgicalapproach to the more severe and intractable obses-sional disorders which have failed to respond toadequate psychiatric treatment. The objective is tointerrupt the cingulum bundle at the probable pointsof circuit closure and to produce small destructvelesions in the medial portion of the posterior orbitalwhite matter of the frontal lobe at the point of con-centration of fronto-limbic interconnections.

TechniqueAbsolute requirements for modern psychosurgery

are safety, so that operative mortality is virtuallyzero and operative morbidity is negligible. Lesionplacement must be accurate and on sound anatomi-cal and physiological bases so that the lesion sizecan be reduced to a minimum and so that validcomparison can be made on clinical analysis to assessthe efficacy of given lesion patterns. Finally, themethod of lesion production should be free fromcomplication or secondary effects, the lesion shouldbe complete at the time of operation and the lesionshould not subsequently alter in size or character.These criteria virtually exclude any freehand methodof surgery and dictate the necessity for an accuratestereotactic technique with the ability to check thesite of lesion making and a predictable method forcircumscribed lesion production.

ProcedureThe operation is usually performed under general

anaesthesia. In order to ensure absolute sterility a

copyright. on June 17, 2020 by guest. P

rotected byhttp://pm

j.bmj.com

/P

ostgrad Med J: first published as 10.1136/pgm

j.49.578.860 on 1 Decem

ber 1973. Dow

nloaded from

Stereotactic limbic leucotomy: surgical technique 861

full head shave is required. The reasons for this arecarefully explained to the patient and the hair re-moval performed after the patient is anaesthetized.We use the stereotactic frame designed by ProfessorLeksell which is illustrated in Fig. 1. It is basically ageometrical open box with radio-opaque graduationson each of the side arms. Upon this frame is shownthe semi-circular arm which carries the electrode orprobe guidance system and is so designed that afterappropriate calculation the tip of the electrode orprobe can be placed at any spatial point within theframe to an accuracy of 1 mm.At the commencement of the operation the frame,

minus the semi-circular arm, is fixed to the patient'shead by drill points which just perforate the outertable of the skull, ensuring rigid fixation to the skulland thus literally fixing the geometric frame in rela-tion to the skull and its contents. With the patient inthe supported sitting position a lumbar air encephalo-gram is performed and X-rays taken in the lateral andantero-posterior projections. The X-ray tube carriesa precision optical bench which attaches to the frame,thus ensuring an unvarying relationship between theX-ray beam, the frame and the patient's head. TheX-ray photographs show the graduations on theframe, the bony structures of the skull and the cere-bral ventricles and main subarachnoid pathways out-lined by the injected air.

Selection of target areasThe standard X-ray projections are shown in

Figs. 2 and 3. Both frontal horns and bodies of thelateral ventricles are demonstrated as is the midlinethird ventricle. Potential target areas in the frontallobe are selected in relation to bony and ventricularlandmarks, a line being drawn vertically at a point1-5 cm anterior to the base of the anterior clinoidprocesses and a second vertical drawn at a point 1 cmposterior to the tip of the frontal horn. The initialtarget areas are usually plotted along the anterior ofthese two lines, defining three areas in the form of atriangle with its apex superiorly. The medial areasare 1 and 1 5 cm above the anterior fossa floor and6 mm from the midline of the third ventricle,whereas the lateral frontal area is 1 cm above theanterior fossa floor and 14 mm from the midline.For the cingulate lesions two pairs of areas are

defined,- being anterior and posterior. The posteriorlesion area is plotted on a vertical line 3 cm posteriorto the tip of the frontal horn of the ventricle and5 mm above the body of the ventricle. The lateraloffset is at the border of the ventricle and the medialarea is 8 mm medial to this. The anterior lesion areasare 12 mm in front of the posterior cingulate sites.

These various zones are plotted on the radiographsand the co-ordinates for each of them calculated inthree dimensions from the stereotactic frame

.~~~~~~~~~

i

FIG. 1. Illustrating stereotactic frame with arc and electrode carrier attached and showing a stimulating electrode inposition.

copyright. on June 17, 2020 by guest. P

rotected byhttp://pm

j.bmj.com

/P

ostgrad Med J: first published as 10.1136/pgm

j.49.578.860 on 1 Decem

ber 1973. Dow

nloaded from

862 Alan Richardson

.I.

.~~

FIG. 2. Lateral radiograph showing stereotactic frame attached to the skull with the ventricular system outline by air.The target zones 1, 2 and 3 in the frontal lobe are shown, as are target zones 4 and 5 for the cingulum bundle.

graduations after making due allowance for magni-fication or rotational factors.

Localization of targetsAt this stage one has a series of seven accurately

defined target zones in each hemisphere, and byplacing the arc on the frame at the appropriate co-ordinates it is possible to pass an electrode or probethrough a skull burrhole to the pre-selected targetpoint. Advantage is then taken of the known elec-trical responses of parts of the limbic system and itsprojections to define the elective target sites. A bi-polar stimulating electrode is inserted to the firsttarget area and stimulation performed with alterna-ting current at 60 Hz at 8-10 V for 15 sec. Duringthis part of the procedure continuous recording ofrespiration, heart rate, skin resistance and forearmblood flow is in progress. The usual response in anactive area is apnoea with less constant changes inpulse amplitude and forearm blood flow. The area ofresponsiveness is usually circumscribed, and movingas little as 4 mm from it may abolish the response. Ifno or little response results the target area is changedby a fixed distance and such studies continued until

an area of suitable activity is identified. An arbitrarylimit of three locations is made to avoid the traumaof repeated electrode insertion. It is rare to fail to findan active area within these limits, and it is similarlynot common to find the target sites in the two hemi-spheres to be asymmetrical.

Careful monitoring of the general anaesthesia hasabated any interference with the effects of stimula-tion, which are in any case only performed when thereadings show the physiological state to be steady.

Methods of focal white matter interruptionInterruptive lesions of white fibre bundles can be

made by a knife, wire loop, a blunt cannula, radio-frequency or radioactive material. The first threemethods involve the probable complication ofhaemorrhage deep in the brain substance, which atworst may be life-threatening or at least produce anarea of brain destruction of unknown or unpredict-able size. Radio-frequency lesions made by unipolarcoagulation at a fixed temperature for a known timeare reasonably predictable in size but may varyaccording to proximity to arteries and may befollowed by secondary haemorrhage or other

copyright. on June 17, 2020 by guest. P

rotected byhttp://pm

j.bmj.com

/P

ostgrad Med J: first published as 10.1136/pgm

j.49.578.860 on 1 Decem

ber 1973. Dow

nloaded from

Stereotactic limbic leucotomy: surgical technique 863

.:..-.....OF

I~~~~~W

AW?! &iX a0

AjE

FIG. 3. Antero-posterior radiograph showing coincidence of the mid-line of the frame and the ventricular system. Thetarget zones in the orbito-frontal region are seen as a triangle with the cingulum target zones plotted above the lateralventricles.

vascular disturbance. It remains, however, a commontechnique used in many centres throughout theworld. Radioactive 90Yttrium in the form of seeds isused by Knight (1965) for focal brain destruction inthe orbital frontal region, but occasionally accurateplacement and movement of the seeds may give riseto difficulties. We currently prefer the use of a cryo-genic probe in most cases, though at times radio-frequency lesions are still used.The probe is a double lumen device using nitrous

oxide as the coolant. Its diameter is 3 mm and theun-insulated tip is 6 mm in length, incorporating athermocouple for continuous monitoring of the tiptemperature. The tip temperature is slowly reducedto - 70°C and this is maintained for 5 min, afterwhich slow temperature rise is allowed by regulatingthe gas pressure. Lesion size is to some extent dicta-ted by the temperature fall, the time duration, thesize of the probe and the rate of re-warming-thelatter having the effect of increasing the lesion size ifperformed slowly. Using a standardized techniquewe have shown a consistent lesion size of 7-8 mmdiameter in other surgically treated patients, where

for the purpose of tumour removal or access it wasfelt necessary to remove a portion of brain and inwhom it was possible to produce a cryogenic lesionprior to this removal. A vertical brain section isshown in Fig. 4 with a spherical dark lesion in thewhite matter deep to the cingulate gyrus some 4months after surgery. Though some contraction insize has occurred the lesion still measures approxi-mately 6 mm in diameter.

In referring to the target areas it was stated thatseven lesion sites or target areas were plotted in eachhemisphere, therefore our current regime in severeobsessional illness is to produce a total of fourteenlesions. A cautious approach in the early cases led usto make fewer lesions initially, and as was seen fromFig. 4 only one lesion is present in the cingulateregion of the left hemisphere, whereas now there arefour in each hemisphere. This gradual increase in thenumber of lesions required was dictated by a re-currence ofsymptoms in some ofthese earlier patientsand the necessity for further operation with the pro-duction of additional lesions. This experience showedthe benefits of the additional lesions which did not

copyright. on June 17, 2020 by guest. P

rotected byhttp://pm

j.bmj.com

/P

ostgrad Med J: first published as 10.1136/pgm

j.49.578.860 on 1 Decem

ber 1973. Dow

nloaded from

864 Alan Richardson

:m~~~~~~~~~~~~~~~~~~~~.......

FIG. 4. A lesion 6 mm in diameter is shown in the cingu-lum bundle. By kind permission of Dr Marion Smith,MRC Unit at the National Hospital, Queen Square,London.

produce any detectable deficits in the patient. Con-fidence was, therefore, gradually acquired that thispattern of lesion was effective in symptom relief andin no way deleterious to the patient.

This technique, though time consuming, has theadvantages of great accuracy of anatomical lesionplacement with secondary target location dependingupon the results of physiological responses to stimu-lation. The cryogenic probe can be entered into thebrain substance without producing brain damage andits use results in a lesion of predictable size un-accompanied by any fear of secondary haemorrhageor reduction in the effective size of the lesion. In theearlier cases where further operation was deemednecessary it was possible, by employing the technique

again, to place further lesions in accurate relationshipto the preceding lesions and thus in a controlled wayto increase slightly the extent of white fibre destruc-tion. In the current series of cases there has been nomortality and only one case suffering a neurologicalcomplication, which was almost certainly due totraversing the head of the caudate nucleus. In thispatient, who had previously had a rostral leucotomy,the orbito-frontal lesions had to be made moreposteriorly than usual; this has led to a modificationof burrhole placement, since which time no furtherdifficulties have arisen.

Post-operative managementRapid recovery of consciousness is the rule follow-

ing surgery and thereafter routine neurologicalassessment is maintained at short intervals for 48 hrand at increasing intervals thereafter. The routinefollows the same pattern as that for any brain surgery.Bedrest is enforced for the first 2 or 3 days until theheadache, due to the intracranial air, subsides.During the 5 to 7 days following surgery someconfusion and disorientation is noted, incontinenceis common and some delay in response is seen. Animmediate lessening of tension is apparent butspecific enquiry concerning obsessional symptoms isnot usually made. The patient is thereafter ambulatedand becomes independent. As the operation is pro-longed, a course of antibiotics is given for 5 days andin view of the remote risk of epilepsy a course ofanticonvulsants is prescribed for a period of 6months. One week after surgery the patient is trans-ferred back to the care of the psychiatric departmentfor the all important programme of rehabilitation.

ReferencesKNIGHT, G.C. (1965) Stereotactic tractotomy in the surgical

treatment of mental illness. Journal of Neurology, Neuro-surgery and Psychiatry, 28, 304.

LEWIN, W. (1961) Observations on selective leucotomy.Journal of Neurology, Neurosurgery and Psychiatry, 24, 37.

LiVINGSTON, K.E. (1969) The frontal lobes revisited. Archivesof Neurology, 20, 90.

NAUTA, W.J.H. (1962) Neural associations of the amygdaloidcomplex in the monkey. Brain, 85, 505.

NAUTA, W.J.H. (1971) The problem of the frontal lobe: are-interpretation. Journal of Psychiatric Research, 8, 167.

PAPEZ, J.W. (1937) A proposed mechanism of emotion.Archives ofNeurology and Psychiatry, 38, 725.

copyright. on June 17, 2020 by guest. P

rotected byhttp://pm

j.bmj.com

/P

ostgrad Med J: first published as 10.1136/pgm

j.49.578.860 on 1 Decem

ber 1973. Dow

nloaded from