A diverse heterogenous group of abnormalities are associated with deafness in syndromic HL. These comorbidities can be visual, skeletal, endocrinal, neurological, skeletal, cardiac, renal, craniofacial, metabolic anomalies [3,4,5]. These disabilities, as visual and learning disorders, could seriously affect the rehabilitation process outcome. However, cochlear implantation improves quality of life of such a group of children and help their care givers to communicate with them by increasing environmental sound awareness [6].

In a study conducted by Broomfeld et al. on syndromic patients, they found a variation in the outcome within the children of the same syndrome. They recommended assessment of these cases on individual basis for CI [2]. There is usually a difference in the penetrance of comorbidities among patients necessitating individual consideration of the handicap of each child. A clear example is the case of extreme CHARGE with multiple severe anomalies, making the implantation the only possible means of communication. In the study conducted by Kay-Rivest et al., they found satisfactory audiological results, and they recommended consideration of CI in CHARGE syndrome to maximize auditory and sensory inputs [7].

The incidence of different syndromes in different populations is not clearly addressed in the literature. The commonest syndromes we encountered in this cohort were found to be JLN (34%) and WS (32%) respectively. This is the first study reviewing syndromic cases who underwent CI in the Egyptian population.

WS is very easily diagnosed by the characteristic phenotypic appearance as well as positive family history. In contrast, JLN usually passes undiagnosed as seen in our study. This implies the importance of doing an ECG routinely for all children undergoing CI, to spot these cases pre-operatively and start medical treatment which can dramatically decrease the incidence of cardiac events. Once diagnosed, this will allow performing the surgery safely. A whole protocol is followed by the anesthesiologist to avoid use of dangerous drugs, tachycardia, hypotension, hypothermia, and electrolytes imbalance (Victoria Scott-Warren). The theater should also be ready to deal with any arrythmias that can develop. Kang et al. confirmed the importance of ECG as first sign of this serious syndrome [8]. In spite of diagnosis and medication intake in these children, follow-up with a cardiologist is essential, as they may need defibrillation or a pacemaker after implantation. JLNS is associated with high risk of sudden death in 25% cases. 50% of JLNS patients had cardiac event at 3 years old [8,9,10]. Broomfield et al. had two cases of JLN who suffered cardiac arrest then sudden death in spite of medical management [11]. Kaneshiro et al. reported JLN case needed defibrillation postoperative after CI surgery [12].

There were no inner ear malformations in any of the cases of JLN and WS, making the surgery straightforward. In the literature, WS can be associated with vestibular aqueduct and semicircular canals malformations [13, 14]. WS outcome of our patients was similar to non-syndromic cases in accordance with De Sousa Andrade et al. [15]. Yanmei et al. found that the hearing and speech outcomes in JLN patients after CI is like other non-syndromic cases [10].

Although the outcome of CI in these cases is not a part of our objectives in this study, but in conjunction with Caragli et al. 2023, the severity of cognitive impairment is inversely proportional to the degree of improvement in auditory and language skills. As these syndromes do not imply any cognitive impairment, the outcome is similar to non-syndromic cases.

The rest of the syndromes were much less common. Some were accompanied by IEM with high incidence of perilymph gusher during surgery, necessitating use of a corking electrode such as Form 24 of Med-EL®. Meticulous radiologic evaluation of these cases to spot the presence of IEM and the status of the cochlear nerve for any deficiencies is of paramount importance.

Middle ear anomalies can be found in syndromes with facial bones affection such as TCS, making the surgery even more difficult or necessitating surgical deviation from standard technique to a more drastic approach such as subtotal petrosectomy. Facial nerve course should be evaluated for any aberrations in cases such as CHARGE association, to avoid intraoperative injury. This will allow counselling of the patient as well as choice of the side to be implanted.

Some syndromes such as KID, necessitate careful surgical incision planning to avoid wound dehiscence due to the inherent skin defect. Prolonged follow-up and explaining the importance of the long-term skin flap care for the parents is essential to avoid skin dehiscence over the device.

Visual co-morbidities present in some syndromes such as retinitis pigmentosa in Usher syndrome, and in CHARGE association and for Albino cases, are considered a big challenge for rehabilitation of such cases. Loundon et al., enhanced the need for early detection of these cases by electroretinography in any child with congenital HL [16]. These cases necessitate early implantation before total visual loss, and preferably bilateral in such a population. Unfortunately, only one device is reimbursed for each child, but we need to implement such a regulation for this group of patients.

CI proved more in these cases to be a multidisciplinary process, as multiple subspecialities may be involved in the decision making and care of these patients, such as genecists, cardiologists, ophthalmologists, anesthesiologists and others. Our study lacked the genetic testing of such cases as it is not routinely available.