Wilder Penfield

The tentorial nerves and localization of intracranial pain in man

HEADACHE AND HEAD PAINS are perhaps among the most common symptoms with which the physician must deal. Better understanding and improved treatment of headache will depend in large measure upon extending our knowledge of the anatomy and physiology of pain-sensitive structures within the head. Previous evidence has indicated that the dura mater is exquisitely sensitive to painful stimulation along the middle meningeal vessels and dural sinuses and at the sites where cerebral veins enter these sinuses. The innervation of these structures and their implication in dural headache were previously reported by Penfield,’ McNaughton,2 and Penfield and M~Naughton,~ and there is no need to cite again the literature reviewed in these reports and in those of Ray and W0lff4 and Wolff.6 It may be noted, however, that the earliest written symbols for dura, from which so much head pain is derived, are found in the Edwin Smith Papyrus, which is an annotated version made in 1700 B.C. of material dating back about five thousand years.6 The ardent bibliographer might well take this ancient series of neurosurgical cases as a starting point for his survey of the relevant literature. The hieroglyphics for meninges occur in one of the case reports describing a patient with a compound depressed skull fracture, the translation reading in part, “the smash is large, opening to the interior of his skull, (to) the membrane enveloping his brain, so that it breaks open his fluid in the interior of his head.” To the unpracticed eye, the symbols appear (Fig. 1) as 2 wavy lines above 2 semicircles, followed by a symbol resembling a hammer. The neurologist or neurosurgeon, unlearned in Egyptology, might be forgiven for taking the waves to indicate cerebrospinal Fig. 1. Egyptian hieroglyphics, the first written symbols for meninges, from the Edwin Smith Papyrus (redrawn from Breasted’)

The supplementary motor area in the cerebral cortex of man.

OSKAR and C~CILE Vogt in their exhaustive studies of the cerebral cortex have striven always to discover the physiological meaning as well as the cytoarchitectonic structure of its cortical fields. They have combined cytological analysis with physiological testing of the same species in a brilliant series of studies tha t must compel the admiration of experimentalists everywhere. Clinicians and physiologists who cannot study function and structure simultaneously must beware of the assumption tha t every functional unit of the cortex has its characteristic cytoarchitectural boundary until this has been proven for each unit. Consequently the following observations of functional localization are made objectively and with provisional cytoarchitectonic agnosticism. Jus t anterior to the sensorimotor area which borders the central fissure of Rolando (precentral and postcentral gyri), there is an area of cortex from which responses (chiefly motor) are obtained by electrical stimulation. This area does not correspond very exactly with the cytoarchitectonie zones outlined by BRODMAZ~, or YON Ecoz~o~o, or CAMPBELL. I t does correspond more nearly with the area 6a beta of VoGT and VOGT (Fig. 1). But the responsive zone does not seem to extend so far onto the lateral surface of the hemisphere. HORSL~r and SCOFFER (1888) showed tha t in monkeys rotation of head, eyes and t runk to the opposite side could be produced by stimulation anterior to the motor cortex. SH~RRI~GrOZ~ and his pupils (L~rTo~ and SH~RRIZ~CTOZ~, 1917) showed tha t within the longitudinal fissure of chimpanzees, stimulation, anterior to the motor strip, occasionally produced movements of shoulder and chest, or thumb and fingers. This is apparently the area to which this report refers.

The interpretive cortex; the stream of consciousness in the human brain can be electrically reactivated.

The interpretive cortex has in it a mechanism for instant reactivation of the detailed record of the past. It has a mechanism also for the production of interpretive signals. Such signals could only be significant if past records are scanned and relevant experiences are selected for comparison with present experience. This is a subconscious process. But it may well be that this scanning of past experience and selection from it also renders the relevant past available for conscious consideration as well. Thus, the individual may refer to the record as he employs other circuits of the brain. Access to the record of the past seems to be as readily available from the temporal cortex of one side as from that of the other. Auditory illusions (or interpretations of the distance, loudness, or tempo of sounds) have been produced by stimulation of the temporal cortex of either side. The same is true of illusional emotions, such as fear and disgust. But, on the contrary, visual illusions (interpretations of the distance, dimension, erectness, and tempo of things seen) are only produced by stimulation of the temporal cortex on the nondominant (normally, right) side of the brain. Illusions of recognition, such as familiarity or strangeness, were also elicited only from the nondominant side, except in one case.

A New Method of preventing Adhesions. The Use of Amnioplastin after Craniotomy.

Laceration of the brain which is the outcome of gunshot wounds of the head, depressed fracture of the skull, and cranio-cerebral operations results in meningo-cerebral adhesion. The adjacent brain comes to be vascularized through a scar from extracerebral blood vessels. This is a most important element in the production of posttraumatic epilepsy. Following the last war Wagstaffe (1928) made a critical stildy of the end-results in a series of soldiers who had received severe head injuries. He found that 1.6 per cent. of these patients became epileptic when the dura had not been penetrated, whereas 18.7 per cent. of those whose dura had been perforated developed post-traumatic epilepsy. It seemed obvious from his figures that penetration of the dura rendered epileptiform seizures ten times more likely to occur. Steinthal and Nagel (1926) concluded that severe injul y to the brain resulted in frank epilepsy in 28.9 per cent. and lesser forms of epilepsy in 35.5 per cent., making a total of 64.4 per cent. In the scars that result from such injuries must lie the secret of the high incidence of post-traumatic epilepsy, which may appear at any time up to ten or fifteen years after the injury (Penfield, 1924, 1927). Head injury without penetration of the dura rarely results in epilepsy, although the brain damage may be, and often is, greater. In such cases adhesions, if they form at all, are much less severe, and blood vessels rarely grow down throuLgh the scar and into the brain. The need for a method to exclude the brain from sLuperficial scars is apparent a method of restoring the subdural space that separates with a thin layer of fluid the pachymeninx from the leptomeninx. The use of amniotic membrane prepared as described below (amnioplastin) seems to solve this problem.

The electrode, the brain and the mind

ConclusionFinally, the brain does function as an integrated whole in one sense. But there are semi-separable mechanisms within that integration. We must continue to study them. This is the way of progress that was begun for us by Fritsch and Hitzig, and Charcot and Jackson.As scientists, we should reserve judgment as to the ultimate nature of things. Meantime we can only use the language of dualism, and speak thus of the mind and the brain. There is no other medium of analytical discussion. The ancient riddle of how brain and mind do interact is still unsolved. But, we begin to understand the brain, if not the mind. The mind receives messages. It seems to direct brain action in the focussing of attention and in voluntary activity.There is a special mechanism for the mind. It can be activated from a distance by an electrode on the interpretive cortex. The mechanism is sometimes arrested by epileptic discharge in centrally placed gray matter. During this activation, consciousness is not lost. During this arrest, consciousness is lost and since other mechanisms continue without control from the minds mechanism, the individual becomes an automaton.Fritsch and Hitzig had stumbled upon the truth. The brain does function, as they said, by “isolated mechanical means.” And we can now perceive the outline of a further truth: The mind is matched by a specific corresponding mechanism in the brain. Human behaviour is determined by interaction of brain and mind.

ABLATION OF ABNORMAL CORTEX IN CEREBRAL PALSY

Cerebral palsy may be defined, in a broad sense, as loss of function due to brain injury. Such injury may affect motor centres producing spastic paralysis of an arm or leg, but it may also affect other areas of the brain and thus cripple other functions than those of movement of the arm and leg. Hemispherectomy has been proposed recently as a method of treatment of infantile hemiplegia by Krynauw (1950) followed by Cairns (1951). The claim made is (1) that cerebral seizures may be stopped, (2) the mental state improved, and (3) motor function facilitated because of a lessening of spasticity in the paretic limbs. In the 12 cases of severe hemiplegia reported by Krynauw this very radical procedure was apparently well justified. The question to be decided is whether less radical ablations may not be preferable. The results reported for these hemispherectomies illustrate the truth of the thesis, to which I have subscribed for some time, that abnormal cortex, incapable of useful service, does, in some cases, exert a noxious influence upon the rest of the brain which miht otherwise function normally Let us examine tis thesis under the headings of epilepsy, mental retardation, and spasticity.