Cochlear implantation in a patient with Perisylvian syndrome*

WENDY SMITH, PATRICK AXON, The Emmeline Centre, Cambridge, U.K.

ABSTRACT Perisylvian syndrome is a rare neurological disorder characterised by the partial paralysis of muscles, epilepsy and mild to severe mental retardation. It is associated with hearing loss and delay in language and speech development. This presents additional challenges in the assessment of whether a child is suitable for cochlea implantation. The method to determine whether the hearing loss is of cochlear or central origin and the progress of a child with Perisylvian syndrome who received a cochlear implant is discussed. Copyright © 2007 John Wiley & Sons, Ltd.

Keywords: Perisylvian syndrome; hearing loss; cochlear implant

Introduction

Perisylvian syndrome also known as Perisylvian dysgenesis and Perisylvian polymi-crogyria is a rare neurological disorder that may be apparent at birth, infancy or later childhood. The underlying anomaly is polymicrogyria (an excessive number of small and prominent convolutions spaced by shallow and enlarged sulci) in the perisylvian areas. Patients with this condition characteristically have diplegia affecting the face, tongue, jaw and throat resulting in diffi culties speaking, chewing and swallowing. Epilepsy has been reported in 50 to 87% (Gropman et al., 1997; Kim et al., 1994; Kuzniecky et al., 1993; Van Bogaert et al., 1998). In most cases

Cochlear Implants InternationalCochlear Implants Int. 8(2), 117–121, 2007Published online in Wiley InterScience(www.interscience.wiley.com) DOI: 10.1002/cii.334

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* Presented at: The MED-EL UK Tenth Annual Workshop, Zell am Ziller, 11–15 January 2006.

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mild to severe mental retardation is present and there may be delays in the devel-opment of certain physical, mental and behavioural skills such as language and speech development. Associated symptoms are thought to be due to the improper development of the cerebral cortex during neural dysmigration. Most cases are sporadic although it may be inherited in a possible X-linked dominant or X-linked recessive fashion. Anomalies in the Xq28 chromosomal region have been identifi ed but the gene responsible has yet to be identifi ed (Villard et al., 2002).

This is the fi rst report in the literature of cochlear implantation in a patient with this syndrome. The additional challenges to the assessment process to deter-mine whether a cochlear implant would be benefi cial as well as the outcome of implantation are discussed.

Case report

A 15 month old boy was seen at the centre to assess whether he would be suitable for a cochlear implant. The infant had been born to unrelated parents at 36 weeks by emergency caesarean due to foetal distress one week after early rupture of mem-branes. He did not require admission to the special care baby unit.

By 9 months the child had failed three health visitor hearing tests and Auditory Brainstem Responses (ABR) demonstrated no response at 90 dB in either ear. No response to sound could be demonstrated even with Danevox hearing aids. By the time of referral, the child had a teacher of the deaf and speech and language thera-pist. He communicated by gesturing. There was no speech and he only occasionally babbled. There was no family history of deafness and his 2 year old sibling was alive and well.

With regards to general development, the child was noted at birth to be a fl oppy baby and suspected of having gross motor delay. The community paediatricians diagnosed trunk hypotonia at 12 months and it was 13 months before he could sit and 21 months before he could walk.

As part of the suitability for cochlear implant assessment, arrangements were made for magnetic resonance imaging (MRI) to be performed and this demon-strated the characteristic appearance of bilateral Perisylvian syndrome (Figure 1). The child developed recurrent ear infections so grommets were inserted at 23 months prior to ABR testing. Binaural aided soundfi eld testing showed no response without vibrotactile stimulation demonstrating that the child had good condition-ing to the test. The grommets were subsequently removed but no response to oto-acoustic admissions (OAEs) was found.

By 22 months the child had developed a right hemiplegia and he was assessed by a speech and language therapist a month later for drooling, choking and infan-tile eating mechanisms. At 25 months a videofl uoroscopy confi rmed a pseudobul-bar palsy.

By 32 months the child was developing language having learnt dozens of signs. This together with the result of the hearing assessments led to the case conference agreeing to offer a cochlear implant. Since the child had developed more problems

Cochlear Implants Int. 8(2), 117–121, 2007Copyright © 2007 John Wiley & Sons, Ltd DOI: 10.1002/cii

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on his right side (diplegia) the decision was made to insert a cochlear implant into the left ear fi rst and if further funding became available to proceed with implanting the right ear subsequently. The child received a Nucleus 24 Contour Advance Cochlear Implant at 2 years 10 months. The implant was inserted with ease and normal impedances, stapedial refl exes and NRTs (Neural Response Telemetry) obtained. Six weeks later initial tuning suggested that the thresholds were lower than the NRTs suggested. He was seen at 1, 2, 10 and 12 weeks post map and on the last visit changed to Advanced Combination Encoders (ACE: Cochlear Corp, Sydney, Australia) map and the child demonstrated a clear response to sound for the fi rst time.

Discussion

This patient demonstrates the diffi culty that can arise in determining whether deafness is central or cochlear in origin. The lack of response to OAEs suggested a cochlear problem but the abnormal MRI scan raised the possibility that a central lesion co-existed. It was encouraging however that by 32 months the child, was developing language having acquired dozens of signs. Before implantation however,

Figure 1: T2W MRI scan demonstrating the polymicrogyria around the sylvian fi ssure.

Cochlear Implants Int. 8(2), 117–121, 2007Copyright © 2007 John Wiley & Sons, Ltd DOI: 10.1002/cii

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it was diffi cult to predict the usefulness of a cochlear implant and the question of which side to implant was a further dilemma.

The diagnosis of Perisylvian syndrome was made on the MRI scan organised by the cochlear implant clinic. Prior to this the child had been noted to have partial muscle weakness and developmental delay and checked to be 46 XY and be negative for Fragile X. Perisylvian syndrome is probably more common than previ-ously thought and should be suspected in any infant or child presenting with oro-motor dysfunction/pseudobulbar signs and developmental delay. Epilepsy is less common and varies in type and severity in the paediatric population (Gropman et al., 1997).

Most can be diagnosed on an MRI scan and as demonstrated in Figure 1 the perisylvian fi ssure and opercular cortex have a polymicrogyric appearance. Ahnlide et al. (2004) however reported Perisylvian syndrome in a patient with a normal MRI scan but a positive ictal Single Photon Emission Computed Tomography (SPECT) co-registered with MRI Subtraction Ictal SPECT Co-registered to MRI (SISCOM) suggesting this condition may in fact be under-diagnosed. Pre-natal diagnosis using ultrasound is diffi cult since folding of even the normal brain con-tinues until birth.

Hearing loss does not appear to be a common feature of Perisylvian syndrome. It was reported in just one of 12 patients (Gropman et al., 1997) and not mentioned in a series of 31 patients (Kuzniecky et al., 1993). In a study of 15 children with normal hearing, IQ > 70, without severe motor or cognitive delay but with devel-opmental language disorder, an association has been found with polymicrogyria and the clinical manifestation was found to vary with the degree of cortical abnor-mality. This has implications for the suitability for cochlear implantation in patients with Perisylvian syndrome since the ability to develop speech and language after surgery relies upon intact central processes (Guerreiro et al., 2002). In our patient OAEs were performed to ensure cochlear function was absent. The ability of the child to develop language was apparent pre-operatively since he had dozens of signs by the time he was 2 years 8 months. Peri-operative recording of stapedial refl exes and NRT was also encouraging. Three months post switch on, this child is vocalis-ing in addition to gestures and now responds to sounds.

The aim when choosing the side to implant is to utilise the ear relating to the better functioning cortex, although the auditory system may not be affected even in the presence of gross abnormalities on the MRI scan. Paetau et al. (2004) have demonstrated using electromagnetic function, plastic changes occur and normal functions may be embedded in unexpected locations. Position Emission Tomography (PET) scanning has been employed to try to assess function however the results are diffi cult to interpret since there is a large variability in the meta-bolic patterns found (Van Bogaert et al., 1998). The decision to implant the left side in this child was made after considering that the diplegia was on the right side implying the left cortex was the worse functionally. Since 80% of the hearing pathway crosses to the opposite cortex, the left ear was chosen to be implanted so the right cortex would be utilised.

Cochlear Implants Int. 8(2), 117–121, 2007Copyright © 2007 John Wiley & Sons, Ltd DOI: 10.1002/cii

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References

Ahnlide JA, Rosen I, Kallen K, Geijer (2004) Ictal SPECT in clinical perisylvian syndrome. Acta Neurologica Scandinavica 109: 280–283.

Gropman AL, Barkovich AJ, Vezin LG, Conry JA, Dubovsky EC, Packer RJ (1997) Pediatric con-genital bilateral perisylvian syndrome: clinical and MRI features in 12 patients. Neuropediatrics 28: 198–203.

Guerreiro MM, Hage SR, Guimares CA, Abramides DV, Fernandes W, Pacheco PS, Piovesana AM, Montenegro MA, Cendes F (2002) Developmental language disorder associated with polymicro-gyria. Neurology 59: 245–250.

Kim HI, Palmini A, Choi HY, Kim YH, Lee JC (1994) Congenital bilateral perisylvian syndrome: analysis of the fi rst four reported Korean patients. J Korean Med Sci 9: 335–340 (Abstract only).

Kuzniecky R, Andermann F, Guerrini R (1993) Congenital bilateral perisylvian syndrome: study of 31 patients. The CBPS Multicenter Collaborative Study. Lancet 341: 608–612.

Paetau R, Saraneva J, Salonen O, Valanne L, Ignatius J, Salenius S (2004) Electromagnetic function of polymicrogyric cortex in congenital bilateral perisylvian syndrome. J Neurol Neurosurg Psy-chiatry 75: 717–722.

Van Bogaert P, David P, Gillain CA, Wikler D, Damhaut P, Scalais E, Nuttin C, Wetzburger C, Szliwowski HB, Metens T, Goldman S (1998) Perisylvian dysgenesis. Clinical, EEG, MRI and glucose metabolism features in 10 patients. Brain 121: 2229–2238.

Villard L, Nguyen K, Cardoso C, Martin CL, Weiss AM, Sifry-Platt M, Grix AW, Graham JM Jr, Winter RM, Leventer RJ, Dobyns WB (2002) A locus for bilateral perisylvian polymicrogyria maps to Xq28. Am J Hum Genet 70: 1003–1008.

Address correspondence to: Mr P Axon, Consultant Otolaryngologist, The Emmeline Centre, Box 163, Addenbrookes Hospital, Cambridge CB2 2QQ, UK. Email: PRAXON@talk21.com