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Bilateral Total Deafness Due to Pontine Haematoma

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Bilateral Total Deafness Due to Pontine Haematoma 62862ournal ofNeurology, Neurosurgery, and Psychiatry 1996;61:628-631 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.61.6.628 on 1 December 1996. Downloaded from SHORT REPORT Bilateral total deafness due to pontine haematoma C A Egan, L Davies, G M Halmagyi Abstract characterised by loud slurred speech with an A 64 year old woman with a predomi- explosive quality; gag reflexes were absent nantly midline pontine tegmental haem- bilaterally and tongue movements were full orrhage presented with bilateral total but slow. There was a profound loss of propri- deafness. One week later reasonable oception in both arms and in both legs but pure-tone thresholds appeared but she touch and pinprick sensation were normal. still had total bilateral loss of speech dis- Limb movements were ataxic, probably due to crimination. At that time contralateral the proprioceptive difficulties, but power was acoustic reflexes were bilaterally absent, full. The tendon reflexes were brisk and both whereas ipsilateral acoustic reflexes and plantar responses were extensor. waves IV and V of the brainstem auditory Brain MRI disclosed an area of low signal evoked potential were bilaterally pre- on T2 weighted images in the dorsal pons, served. It is proposed that this patient's abutting the fourth ventricle, especially on the hearing deficit was due to inactivation of left (fig 1A). The Ti weighted images showed the ventral acoustic striae decussating in subtle signal attenuation in the same distribu- the trapezoid body. This case supports tion. The changes were typical of haemor- the contention that in humans the ventral rhage. In addition, there was a small, old, pontine acoustic decussation carries most lacunar infarct in the left lentiform nucleus. of the neural signals required for hearing There was no cerebral cortical abnormality. and perhaps all the neural signals Over the next few days she recovered the required for speech perception. ability to hear and to discriminate environ- mental sounds such as a telephone ringing, (J Neurol Neurosurg Psychiatry 1996;61:628-63 1) water running, footsteps, and a knock at the door, but remained unable to understand any spoken words. Keywords: deafness; speech perception; brainstem; Pure-tone audiometry showed a bilateral, http://jnnp.bmj.com/ trapezoid body; auditory evoked potentials moderately severe, sensorineural hearing loss (fig 2). The auditory system decussates at several levels Speech audiometry showed that speech dis- in the brainstem. There is no general agree- crimination was bilaterally absent to both ment on the relative importance of the ipsilat- recorded and live voices even at 100 dB. (The eral as opposed to the contralateral ascending expected speech discrimination score if these auditory pathways in humans, in part because pure-tone thresholds were due to cochlear there are so few studies of hearing in patients lesions would be about 50% at 80 dB.) on September 29, 2021 by guest. Protected copyright. with well localised brainstem lesions. Here we Acoustic reflex testing showed that ipsilateral report a patient who temporarily became acoustic reflexes (ARs) were present from each totally bilaterally deaf from a single pontine ear at normal thresholds at 500, 1000 and lesion which involved the trapezoid body. 2000 Hz. Contralateral ARs were bilaterally absent. Brainstem auditory evoked potentials (BAEPs) Neurology Case report were elicited using 100 dB, 100 ps white noise Department, Royal Prince Alfred A 64 year old hypertensive woman collapsed rarefaction clicks at 12 Hz. On stimulation of Hospital, Sydney, without loss of consciousness after a brief the right ear ipsilateral waves I to V were Australia episode of right sided paraesthesia and numb- recorded at normal latencies (fig 3). On stimu- CA Egan ness. She was a native English speaker with no lation of the left ear waves II to V L Davies ipsilateral GM Halmagyi previous hearing problems. On examination were recorded at normal latencies; wave V Correspondence to: she was fully conscious and alert but was seemed to be reduced in amplitude and wave I Dr GM Halmagyi, RPA totally deaf. She was able to lip read a little was obscured by stimulus artefact. Hospital, Camperdown, NSW 2050, Sydney, and so could give appropriate answers to simple After a month some speech comprehension Australia. spoken questions. She could read with com- had returned. One year later there was only a Received 25 September 1995 prehension. She had a left lateral gaze and a mild pure tone sensorineural hearing loss on and in revised form 29 April 1996 right abducens paresis. There was no facial the left with 100% speech discrimination at Accepted 5 June 1996 weakness but there was a severe dysarthria 50 dB, and a mild to moderate pure tone hear- Bilateral total deafness due to pontine haematoma 629 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.61.6.628 on 1 December 1996. Downloaded from 121~~~~~~~ 9 13 A B Figure 1 (A) T2 weighted axial MRI showing a recent midline haemorrhage in the pontine tegmentum at the level of the vestibulocochlear nerves. The lesion is well clear ofthe cochlear nuclei (B) Schematic representation of brainstem structures at a level near the MRI shown in (A). From the clinical signs the main structures involved in the lesion apartfrom the trapezoid body (5) were: both medial lemnisci (7), both abducensfascicles (9) and the medial longitudinalfasciculus on the left (12). The cochlear nerves (1), the dorsal and ventral cochlear nuclei (2,3), the superior olivary nuclei (4), and the dorsal acoustic striae (6) were spared. Other structures shown in thefigure, all spared, are the abducens nucleus (8); vestibular nerve (10); vestibular nucleus (11);facial nucleus (13);facial nerve (14), descending nucleus and tract of the trigeminal (15); tractus solitarius (16); central tegmental tract (17); anterior spinocerebellar tract (18), and inferior cerebellar peduncle (19). (Modifiedfrom Nieuwenhuys et al. The human central nervous system. New York:Springer Verlag, 1988.) ing loss on the right with 85% speech discrim- than the ipsilateral ARs. The other neurological ination at 70 dB (fig 2). The contralateral ARs deficits had also resolved except for a moder- had returned but were smaller in amplitude ately severe left proprioceptive hemisensory Right ear Left ear 0 20 September 1993 SDS = 0% (100 dB) _ SDS = 0% (100 dB) http://jnnp.bmj.com/ 40 _ 60_ 80 A 100 A A v v v 120- v v v v v I I I I I I I I I on September 29, 2021 by guest. Protected copyright. -00 20 February 1995 SDS =70% (50 dB) _ 40 _ , 60 \ SDS =100% (50 dB) 80 _ 100 _ - V V 120 II I I I I I I I 250 500 1000 2000 4000 8000 250 500 1000 2000 4000 8000 Hz Hz Figure 2 Pure tone audiograms, acoustic reflex thresholds, and speech discrimination scores (SDS) during the period of bilateral speech deafness (top row) and 18 months later when hearing was almost normal (bottom row). Note that when the patient had no speech discrimination from either ear, pure tone thresholds were reduced by only 30-70 dB; at that time ipsilateral acoustic reflexes were present at normal thresholds (A) whereas contralateral acoustic reflex could not be elicited with maximal stimulus intensity (V). (Note that at 4000 Hz the acoustic reflex can be absent in normal subjects.) Eighteen months later contralateral acoustic reflexes (V) had returned. 0 = right ear pure-tone threshold; X = left ear pure-tone threshold; A = ipsilateral acoustic reflex threshold (A = absent reflex); V = contralateral acoustic reflex threshold (V = absent reflex). 630 Egan, Davies, Halmagyi J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.61.6.628 on 1 December 1996. Downloaded from Figure 3 Brainstem auditory evokedpotentials in response to 100 dB NHL, 100 ps, 12 Hz white noise rarefaction clicks recorded on the same day as the audiogram on the top row offig 2. From top to bottom: right ear stimulate-left ear record (R-L); right ear stimulate-right ear record (R-R); left ear stimulate- left ear record (L-L); left ear stimulate-right ear record (L-R). On stimulating the right ear, ipsilateral waves I to V were recorded at normal latencies. On stimulating the left ear, ipsilateral waves II to V were recorded at normal latencies; wave Vseemed to be reduced in amplitude and wave I was obscured by stimulus artefact. http://jnnp.bmj.com/ on September 29, 2021 by guest. Protected copyright. Ear Wave I Wave Wave 11I Wave IV Wave V I-Ill I-V III-V Right 1.7 2.6 3.6 4.9 6.1 2.9 4.3 2.4 Left 2.9 3.9 5.2 6.2 2.3 loss producing arm and leg sensory ataxia. that the lesion was more extensive than in our Both plantar reflexes were still extensor. patient and probably involved both superior olivary nuclei.' Although bilateral selective impairment of speech discrimination with Discussion preservation of pure tone thresholds has been could one We find only previous case report of reported with brainstem lesions23 we could bilateral total or subtotal deafness due to a sin- find no previous report of bilateral total loss of gle pontine lesion. This was a patient who was speech discrimination due to a single brain- locked-in and had no ARs at all, suggesting stem lesion. (In this discussion it is important Bilateral total deafness due to pontine haematoma 631 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.61.6.628 on 1 December 1996. Downloaded from to distinguish between bilateral total deafness peduncles, and the central tegmental tracts- followed by total loss of speech discrimination were functionally spared. It seems then that due to a single pontine lesion as reported here not only was the trapezoid body inactivated by and the following: bilateral total deafness due the lesion in this patient, but that it was the to multiple pontine lesions4; bilateral total only auditory structure inactivated by the deafness due to midbrain lesions5; unilateral lesion (fig 1B).
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