sion at the knee and hip if these should happen to occur. BRAIN and CuRRAN found that this reflex was elicitable in all children aged nine months or less, and in almost all aged under a year, while it had disappeared in all but one child over the age of two years. The foot grasp reflex was found to be absent in two infants aged six months who both suffered from bilateral pyramidal lesions and exhibited marked spasticity. They pointed out that the presence of grasp reflex of the foot thus corresponded roughly with the normal persistence of the extensor plantar reflex in infancy. BR¡,ru and Cunn,c.n observed that the foot grasp reflex was fairly common in Mongolian imbeciles. They investigated the reflex in fifty-nine such pa' li, tients, ranging from one to forty-five years of age. They found it present in both feet in twenty-three and in one foot only in five. It was absent in twenty and the result was doubtful, mainly owing to the difficulty of examination, in eleven. Thus. the reflex was obtainable in one or both feet in approximately half the cases. It was rarely observed in Mongolian imbeciles after the age of twenty' Up to that age it was present in twenty-five out of forty-two patients; aftef that age in only three out of seventeen' Bn¡.I¡r aná Cunn¡rv also reported four additional cases of organic lesions of the nervous system lea' ding to grásp reflex of the foot. The first was a natÉnt wlth co.teenital choreo-athetosis of bilateral hirtribrrtioo. Thi! patient, a child aged two and a half years, showed no grasp reflex o-f- the .hands, but a vigorous grasp reflex was readily elicitable in both feet. The slightest contact with the flexor surface of the toes, ór the disal half of the sole, evoked strong flexion of all the toes, which were maintained ii tonic flexion for a quarter to half a minute or longer. The second patient h-ad un unve- ,ifi.d ,u*o.rt "of th" corpus callosum. She exhibited bilateral weakness with some spasticity and extensor nlantar responses associated with'un extremely li' e.a'sp ,"flex of both hands and both feet' iil" ,ftitá patient had a subdural haematoma on the "orou, ti* ";¿" *hi"h ptobably been present for at least ii?"" *"ttlls. Hl also showed bilateral signs of a ly."*i¿"f lesion and in addition the grasp reflex Mnnrcr¡u Cr,Íxrcl Touo XV <strong>1950</strong> - Núm. 5 was readily elicitable from both hands and both {eet, being more virogous in both insteances on the right side. The fourth patient had a meningioma of the falx which was embedded in the medial aspect of the left frontal lobe reaching pack to within about 2 cm. of the precentral gyrus. This patient had a right hemiparesis and hemi-apraxia with marked verbal dysphasia. A strong grasp reflex was present in the right hand and also in the right foot. Gorrlsretl ( I93B) contributed a further study of the grasp reflex of the foot which he termed . He related it to a lesion of the opposite frontal lobe and explained it as a response of the lower mechanisms in the higher centres of the damage. He emphasised its value as an early sigu of the frontal lobe lesion and pointed out that when it appears on the ipsilateral side it indicates an extension of the pressure to the hemisphere on the side opposite to the lesion. Pnysror.ocrclr- Aspncrs. - The physiology of the grasp reflex has been studied by Rrcrirn anJ'Hrwrs (1932) and by Fur-ror,r and his collaborarors (1932, 1936, l93B) and this aspect of the subject has recently been well s-ummarised by FulroN (1943). Animal expeiiments have shown that the grasp reflex is produced in monkeys and chimpanzees by isolated removál of the promotor area. It is present in animals in which the motoi and premotor areas have been removed bilaterally, and its "ir..u"t".istics are found also in animali which have been rendered completely thalamic through removal of both hemisph-eres. lt appears to be dependent upon lhe integrity of the tegmentum since ii is not irecessary for the striatum and anterior port of the thalamus io be present in order that the response may be elicitable. Fulror describes ir as a flexoi response of the digits postural in character and it is affected by change of the position of the body in space, togethei ¡uith lther ,postural reactions. Thus, it ii a reléase phenomenon which is the result of the d'estruction of i.*" n¡.". originating in the premotor cortex which normally inhibir it. Ruce¡'tr cLrNrcAL oBSERvATroNs.-An excellent review of the whole subject has recently been published by MnssroN-VBRNroRy (1948) and new -observations have been made by Ssyrranrn and Dr¡v. Ny-BRowN (1948). These authors distinguish the glasp reflex from the instinctive grasp reaction. They define the grasp reflex as na siereótyped prehensile reaction of the flexors and the adductori of the fingers and the flexor muscles of the flexors and the adductors of the fingers and the flexor muscles of the wrist which can be elicited in fractional parts by appropriate localisation of the stimulus.> The adequate stimulus for the full reaction is dual. The first essential is a distally moving deep pressure over a specific area of the palmar surface of joints in the hand which elicit a rapid, brief muscular contraction ( phase), which de. velops into a strong phase only i{ traction is made upon the tendons of the flexor and adductor muscles thus thrown into preliminary con-, traction. Response is then maintained only by traction, The instinctive grasp reaction, according to
Toruo XV Núm. 5 - <strong>1950</strong> W. Russrll Bn-lrx. - Grasp reflex 295 Sryrr'¡Rrn and DenNy-BRowN, is a motor activity of a higher grade than the grasp reflex. They state that
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