ltal. J, Neurol. Sci. 13:507-510, 1992 Clinical and neuroradiological findings in a case of pure word deafness Di Giovanni M.*, D'Alessandro G.*, Baldini S.*, Cantalupi D.**, Bottacchi E.* * Divisione di Neurologia, Ospedale Regionale di Aosta ** Divisione di Medicina Nucleare, Ospedale Regionale di Aosta Pure Word Deafness is a clinical syndrome included among the aphasias and is marked by complete deafness of sudden onset with conserved ability to understand and read the written word and with no speech disorders. We report the case of 61 year old man in whom pure word deafness developed after two episodes of acute cerebral ischemia in quick succession. Neuroimaging procedures, that is: computed tomography scan, single photon emission computed tomography and magnetic resonance imaging, revealed the presence of two ischemic lesions in the temporal cortex bilaterally. Neurophysiological investigations (electroencephalogram, brainstem auditory evoked potentials and stapedial reflex) were also studied. We discuss the outcome of all these investigations in the light of the relevant published work. Key Words: Pure word deafness - - temporal ischemia - - SPECT Introduction The human auditory cortex lies in the superior temporal gyrus along the sylvian fissure, known as the gyrus of Heschl, corresponding to Brodmann areas 41-42 and 22, and each ear has a bilateral representation on the cerebral cortex, as demonstrated by numerous neurophysiological studies [12, 16, 221. Auditory deficits in man depending on isolated brain lesions may be of several types [11, 17]. Unilateral lesions of the temporal cortex give rise to a mild auditory deficit that may consist in difficulty in discriminating distorted or elided phonemes sounded at the contralateral ear [8, 20]. Bilateral lesions of the superior temporal cortex, a rare occurrence in man, may cause an auditory deficit known as pure word deafness (PWD) [1, 4, 7]. It may present in isolation or in association with other focal neurological signs and is marked Received 29 April 1991 - Accepted 30 July 1991 by a complete auditory deficit with total sparing of the peripheral auditory receptor, and so the patient does not understand the spoken word but is perfectly able to carry out written commands, read and express himself correctly [6]. It is thus a highly selective and peculiar form of sensory aphasia [ 10]. We present a case of PWD studied by neurophysiological and neuroimaging procedures and discuss the findings in the light of the available published data. Case report This 61 year old righthanded man was admitted to the Neurology Division of Aosta Regional Hospital the day after onset of a mild motor deficit on the left side. No disturbances of consciousness or of language were reported on admis507 The Italian Journal of Neurological Sciences sion. The past pathological history revealed that the patient had suffered for some years from a hypokinetic cardiomyopathy with mitral insufficiency and chronic atrial fibrillation (confirmed by EKG), treated on and off with verapamile, and in relative hemodynamic compensation. Neurological examination on admission showed only a left facio-brachio-crural hemiparesis with no sensory or language disorders and no other neurological signs. Computed tomography brain scan (CT-scan) on admission imaged a corticosubcortical hypodense patch about 2 cm in diameter in the right temporal lobe with no enhancement after contrast injection and no mass effect, attributable to ischemia. On day 6, while the left hemiparesis was receding, the patient presented a sudden clinical deterioration. Neurological examination elicited no new deficits, motor or sensory. The patient was agitated and confused but alert; he failed to respond to acoustic stimulation applied to either ear but he was perfectly capable of understanding written language and of obeying written commands. He had no phasic expressive disturbances. A few hours later a second CT brain scan confirmed the ischemic area in the right temporal lobe and onset of another, faint, specular ischemic lesion in the left temporal lobe, smaller than the former and, like it, did not enhance (Fig. 1). On the same day a cerebral blood flow study was done with single photon emission computed tomography (SPECT): injection of 900 MBq of 99m_ Tc-HMPAO (hexamethylpropyleneamineoxime) by intravenous bolus followed by 20' recording with reconstruction of 6 mm. transverse-sagittalfrontal slices, which were subsequently put together in 1,8 cm. sections. The cerebral blood flow study highlighted a clear "cold" area with scant perifocal uptake in the posterior portion of the right temporal lobe and another "cold" area with intense perifocal uptake in the left temporal lobe involving also the subcortex (though the SPECT study showed mainly the blood flow distribution in the cortex. Fig. 2). Neurophysiological and neuro-otological tests were then done. Electroencephalogram on day 10 showed theta waves over the midtemporal regions bilaterally. Brainstem auditory evoked potentials on supramaximum monaural click stimulation at 100 dB (it being impossible to establish a threshold value) showed the presence of normal response waves bilaterally, the values being within normal limits (I:1800 msec; III:3720 msec; V:5520; IIII:1920 msec; III-V:1800 msec; |-V:3720 msec). Integrity of the peripheral receptor was proved by a normal stapedial reflex on both sides at the frequencies 500-1000-2000 Hz. The tympanogram 508 Fig. I. CT-scan on day 6 imaging two corticosubcortical hypodensities, one in the right and one in the left temporal regions. Fig. 2. SPECT images the "cold" area in the right temporal lobe and the "cold" area with perifocal "hot" halo in the left temporal lobe. Di Giovanni M.: A case o['pure word deqOwss Discussion Pure word deafness, first described by Lichtein in 1885 [15], is a disorder in which the subject is unable to understand the spoken word, repeat words or write under dictation while his ability to speak, write and read is unaffected. Single reports [14, 18] followed under other names, none of which has been universally accepted. Pure word deafness remains the most widely used term. The lesion responsible affects the midposterior region of the superior temporal gyrus [2]. Wolfart [21] proposed as explanation an interruption of nerve fiber tracts that run from the auditory cortices to the Wernicke area of the dominant hemisphere. The typical auditory deficit may arise even after a single cortical lesion [9], but more often bitemporal lesions. In the majority of cases the lesion is ischemic [6, 8]; possible but very rare are neoplastic or traumatic lesions [10]. Pure word deafness rarely presents in isolation. It is usually combined with other neurological deficits: hemiparesis (right or left), aphasia, nystagmus, pontine hemorrhage, dysarthria, hemianopia [3, 5, 18, 19]. The deafness remains total in the great majority of cases even after 3-7 years [9, ~31. Fig. 3. MRI i, the Ti-weighted seque,ce shows two images of a signal in the temporal lobes, more marked on the right. pattern was likewise normal bilaterally. Tests for ideomotor, buccofacial and object-use apraxias revealed no abnormality of function. A month after the episode magnetic resonance imaging of the brain with spin-echo and double echo at TR 2400, TE 35-90 (Fig. 3) imaged a circumscribed area of altered signal intensity in the right temporal lobe posteriorly marked by a lengthening of the T~ and T2 relaxation times. Another area of altered signal, though less well defined, in the left temporal lobe involving part of the most posterior portion of the insular cortex indicated evolving ischemic areas. Clinical and instrumental examination 6 months after the onset of symptoms showed full recovery from the left hemiparesis and no other deficits. The pure word deafness persisted. The patient understood the gist of the spoken word, through practice grasping much by lip reading. He understood the written commands and word perfectly and had no difficulty in expressing himself. A final CT scan on the same day confirmed the presence, withouth noteworthy differences, of the two ischemic areas. The analysis of our case substantially confirms the published data [2, 7, 8, 21]. Our patient had had two separate episodes of cerebral embolism of cardiac origin (atrial fibrillation), the first of which had produced an ischemia in the right temporal cortex (with secondary left hemiparesis, which later cleared) and the second an ischemic patch in the left temporal cortex, which caused the sudden and complete auditory deficit. Thus in our subject too the brain lesion was double and the typical auditory deficit was practically isolated, with no neurological deficits on either side (the left hemiparesis had appeared p r e v i o u s l y and cleared spontaneously after 6 days); so it was a true case of pure word deafness. Six months later PWD persisted. Instrumental analysis showed the integrity of the peripheral acoustic receptor and the pathways of brainstem nerve conduction: normal tympanogram, stapedial reflex and brainstem acoustic evoked potentials. The pathology was provenly cortical, as shown by neuroimaging procedures (CT scan, magnetic resonance imaging, SPECT scan). The most important of our findings was the cerebral blood flow assessment with SPECT, the use of this procedure not having been reported in the cases of pure word deafness described. The SPECT examination with 99m-Tc-HMPAO within a few hours of onset of the auditory deficit clearly showed the two "cold" areas of decreased flow in the posterior regions of the temporal cortices. 509 The Italian Journal of Neurological Sciences Characteristic was the appearance in the left temporal cortex (second ischemic area) of a "cold'" area of hypoperfusion, but of very recent formation, since it still had a "hot" halo of increased flow, to be interpreted as a perifocal "luxury perfusion". This finding is very important, even mo- re than the classic C T scan evidence, because it permits a hemodynamic evaluation within a "few hours of the ischemic event. Magnetic resonance imaging confirmed the c o m p u t e d thomography scan data but, though better defined, added nothing of consequence. Sommario La sorditb verbale pura b una sindrome di non frequente riscontro, inquadrata tra le forme di afasia, caratterizzata da sorditfl completa e conservata possibilitb di comprendere e leggere il messaggio scritto, senza turbe espressive dell'eloquio. In genere il quadro clinico si presenta associato ad altri deficit neurotogici focati importanti e molto raramente, come nella nostra esperienza, in f o r m a isolata. Viene descritto il caso di un uomo di 61 anni, cardiopatico, che ha presentato una sorditgt verbale pura in seguito a due episodi, ravvicinati nel tempo, di ischemia cerebrale acuta. I1 paziente b stato studiato con tecniche di neuroimaging: TAC, S P E C T (non sono presenti in tal senso dati in letteratura), RMN; e neurofisiologiche: EEG, BAER, Stapedial reflex. Le conclusioni sono esaminate alla luce dei dati e dei lavori presenti in letteratura. Address reprint requests to: Dr. Marco Di Giovanni U.O. di Neurologia Ospedale Regionale Viale Ginevra 3 - 11100 Aosta References [1] BANES F.H., CHATRIANG.E., MESHER R.A., SUMI S.M.: A case of persistent cortical deafness. Neurology 38:1490-1439, 1988. [2] BRAIN L.: Speech disorders. B&C publishers, London, 72-73, 1965. [3] CHAVANYJ.A.: Un cas de surditd d'origine corticale. Presse med. 53:472, 1945. [4] EARNEST M.P., MONROE M.A., YARNELL P.R.: Cortical deafness demonstration of the pathologic anatomy by CT-scan. Neurology 27:1172-1175, 1977. [5] GAZZAN1GAM.S., VELLETRIA., SARNOM.T.: Pure word deafness and hemispheric dynamics: a case history. Cortex 9:136-143, i973. [6] GOLDSTEIN M., BROWN M., HOLLANDER J.: Auditory agnosia and cortical deafness: analysis of a case with three-year follow-up. Brain Lang. 2:324-332, 1977. [7] GOLDSTEIN M.N.: Auditory agnosia for speech (pure word deafness); a historical review. Brain Lang. 1:195-204, 1974. [8] GRAHAM J., GREENWOODR., LECKRY B.: Cortical deafness. J. Neurol. Sci. 48:35-49, 1980. [9] HEAD H.: Aphasia and kindred disorders of speech. C.U.P. London pp. 125-127, 1926. [10] HOWE J.R., MILLER C.A.: Midbrain deafness following head injury. Neurology 25:286-289, 1975. [11] JERGERJ., WEIKERS N., SHARBROUGHF.: Bilater510 al lesions of the temporal lobe. Acta oto-laryng. suppl. 258, 1969. [12] KANSHEPOLSKYJ., KELLEY J., WAGGENERJ.: A cortical auditory disorder. Neurology 23:699-705, 1973. [13] LEICESTER J.: Central deafness and subcortical motor aphasia. Brain Lang. 10:224-242, 1980. [14] LEMOYNEJ.: La surdit~ corticale. Ann. otolaryng. 62:133-140, 1944. [15] LICHTEINM.: On aphasia. Brain 7:433-485, 1885. [16] MENDEL M.I.: Clinical use of primary cortical responses. Audiology 19:1-15, 1980. [17] MlCHEL F., PERONNET F., SCHOTT B.: A case of cortical deafness: clinical and EEG data. Brain Lang. 10:367-377, 1980. [18] MILLS C.K.: On the localisation of the auditory centre. Brain 14:466-472, 1981. [19] MOTT F.W.: Bilateral lesions of auditory cortical centre. Br. Med. J. 2:310-315, 1907. [20] OPPENHEIMERD.R., NEWCOMBEF.: Clinical and anatomical findings in a case of auditory agnosia. Arch. Neurol. 35:712-719, 1978. [21] WOLFART G., LINDGREN A.: Tableau clinique et anatomo-pathologique dans un cas de surditg verbale pure. J. Nerv. Ment. Dis. 116:816-827, 1952. [22] WOOLSEY C.N.: Organisation of the cortical auditory system. In Roseblinthna (Editor), Sensory Communication. Cambridge Mass, The Mitt Press, Chapt. 14: 235-238, 1961.