Predictive factors of vertigo following cochlear implantation in adults

OBJECTIVES

The occurrence of vertigo after cochlear implantation surgery is one of the most common complications, and often transient. The purpose of this study was to evaluate the occurrence of vertigo after unilateral or bilateral cochlear implantation as well as to identify potential predictive factors.

MATERIALS AND METHODS

Patients who have undergone cochlear implantation and vestibular assessment pre- and postoperatively were included retrospectively. The presence of vertigo before and after surgery was noted. Postoperative vertigo duration was divided into 3 categories: immediate postoperative (less than 2 months), transient postoperative (between 2 months and 1 year), and persistent postoperative (greater than 1 year). Pre- and postoperative vestibular assessment results (caloric irrigation and VEMP tests) as well as patients' age, operated side, surgical technique for round window access, and characteristics of the electrode array were all analyzed as potential predictive factors of postoperative vertigo.

RESULTS

A total of 166 cochlear implants (137 patients) were included in the study, with a mean age of 57.5 ± 16.4 years. Of these, 36% developed postoperative vertigo, of which 19.3% was immediately postoperative. At 1 year postoperatively, 6 cases (3.6%) had persistent disabling vertigo, with 2 cases (1.2%) having no history of vertigo prior to cochlear implantation. Regarding caloric irrigation, 21% of the patients had a vestibular deficiency before surgery, and the same percentage had decreased vestibular responses. At 2 months after cochlear implantation, 31% of the patients exhibited an alteration in their vestibular test results, and 23.5% had experienced immediate postoperative vertigo. None of the factors studied (age, operated side, surgical technique, electrode array characteristics, and vestibular test alteration) correlated with the occurrence of short-term or long-term postoperative vertigo.

CONCLUSION

The occurrence of vertigo after cochlear implantation is difficult to predict by the healthcare team and may develop into an invalidating condition. Each vestibular examination performed routinely only evaluates a specific vestibular organ dysfunction. Therefore, combining several vestibular assessments tests before and after cochlear implantation can increase their sensitivity of predicting the occurrence and eventual persistence of this symptom.

French Society of ENT (SFORL) guidelines (short version): Audiometry in adults and children

INTRODUCTION

French Society of ENT (SFORL) good practice guidelines for audiometric examination in adults and children.

METHODS

A multidisciplinary working group performed a review of the scientific literature. Guidelines were drawn up, reviewed by an independent reading group, and finalized in a consensus meeting.

RESULTS

Audiometry should be performed in an acoustically controlled environment (<30dBA); audiometer calibration should be regularly checked; and patient-specific masking rules should be systematically applied. It should be ensured that masking is not overmasking. Adult pure-tone audiometry data should be interpreted taking account of clinical data, speech audiometry and impedancemetry. In case of discrepancies between clinical and pure-tone and speech audiometry data, objective auditory tests should be perform. In children aged 2 years or younger, subjective audiometry should be associated to behavioral audiometry adapted to the child's age. In suspected hearing impairment, behavioral audiometry should be systematically supplemented by objective hearing tests to determine and confirm the level and type of hearing impairment.

[Vascular involvement in Cogan's syndrome. A case report]

Vascular manifestations of Cogan's syndrome are rarely reported. We report the case of a young woman followed for typical Cogan's disease. Serious vascular involvement was found only during work-up for arterial hypertension. This case highlights potentially asymptomatic nature of extensive vasculitis affecting large and medium-sized vessels in Cogan's disease. Careful screening is required to prevent life-threatening complications.

[Study of a case of cochlear implant with recurrent cutaneous extrusion]

OBJECTIVE

An observation of a difficult-to-diagnose complication of the cochlear implant: recurring cutaneous extrusion of a cochlear implant is reported.

PATIENTS AND METHODS

The history of an adult patient with total deafness is reported. She received an implant in her right ear in 1988, which was then explanted because of absence of hearing results. She received a second implant in her left ear in 2002, which was then explanted in 2007 because of cutaneous extrusion. In 2008, a second implant of a different brand was placed in her left ear, with the central part placed away from the first site, but extrusion recurred. A new attempt to encapsulate the central part with a hydroxyapatite box also ended in extrusion and was explanted in 2008.

RESULTS

Various diagnoses to explain these cutaneous problems were suggested during this clinical progression: infection, allergy, and a reaction to a foreign body. No hypothesis could be clearly ruled out.

CONCLUSION

Cutaneous complications after cochlear implant are exceptional. As soon as cutaneous disorders appear, a rigorous diagnostic process must be followed so that the patient can be recommended a long-lasting solution to restore quality hearing.

Prothèse acoustique et bruiteur conjoint pour des sujets hypoacousiques et acouphéniques

INTRODUCTION

Sound therapy has been studied in a group of 30 patients experiencing hearing loss and tinnitus.

MATERIAL AND METHODS

Patients wore a BTE hearing-aid (TCI-COMBI by Siemens), which, in addition to acoustic amplification, can generate a broadband noise. Comparison of self-questionnaires completed by the patients during a 12 week period with amplification alone to a 12 week period with amplification and noise.

RESULTS AND CONCLUSIONS

His study demonstrates that the level of suffering is significantly reduced during the period with added noise.

Tone decay at threshold with auditory electrical stimulation in digisonic cochlear implantees

The present study aims to evaluate tone decay (auditory adaptation) in Digisonic cochlear implant patients, and to compare tone decay results with speech recognition performance. The following criteria are evaluated: tone decay occurrence, place effect, pulse rate effect, and correlation with speech recognition. A great variability in tone decay was found among the subjects. The amount of tone decay, measured as a percentage of the electrical dynamic range, depends to some extent on electrode location, which may be linked with the frequency dependence of acoustical tone decay. However, it is likely that acoustically and electrically evoked adaptation does not involve the same process. Also, an effect of pulse rate was found. However, no relationship between the amount of tone decay and speech recognition abilities was observed. Evaluation of tone decay in cochlear implant patients might not only allow further evaluation of the condition of their auditory system, but also provide a means to determine preoperatively the specific characteristics of a subject's residual auditory capacities.

[From the concept of permanent percutaneous connections to that of permanent percutaneous electrical connections]

Percutaneous abutment of an extra-oral implant provides two main functions: support of bone anchored hearing aid (BAHA) and fixing maxillofacial prosthesis (MFP). Further developing this concept, and using available surgical strategies and materials, leads to a new application in extra-oral implantology. We analyzed the evolution of concepts in the field of permanent percutaneous connection (PPC) to the new concept of PPEC (permanent percutaneous electric connection), presenting a clinical case.

Expression of NMDA, AMPA and GABA(A) receptor subunit mRNAs in the rat auditory brainstem. I. Influence of early auditory deprivation

Impact of early post-natal deafening on auditory pathways was investigated in newborn rats deafened by daily amikacin injections from P7 to P16 inducing a complete destruction of the organ of Corti. The expression of mRNAs encoding N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole (AMPA) and gamma-aminobutyric acid type A (GABA(A)) receptor subunits was then studied by in situ hybridization in the dorsal and ventral cochlear nucleus and in the central nucleus of the inferior colliculus (CNIC). Early post-natal deafening decreased bilaterally the expression of mRNAs encoding NR1, NR2a, NR2b and flop isoforms of AMPA receptors. On the contrary, it increased the expression of mRNAs encoding some GABA(A) subunits (alpha1, beta1, gamma2) and flip isoforms of AMPA receptors. These changes were more pronounced in cochlear nuclei than in CNIC. They suggest that auditory sensation is essential in the normal development of central auditory pathways.

[Functional imaging of the auditory cortex: role of magnetoencephalography]

We present the different methods for detecting cerebral activity in the auditory cortex. Positron emission tomography (PET) and functional MRI (fMRI) measure such activity indirectly by calculating the blood flow rate or the consumption of oxygen. The direct methods of detection record the electrical or magnetic activity by eletroencephalography (EEG), or magnetoencephalography (MEG), respectively. The aim of this study was to define the role of MEG amongst these different techniques using the data from recordings of evoked magnetic fields in 5 healthy subjects. The localizations demonstrated the tonotopic organization of the auditory cortex, with high-pitched sounds showing a more medial cortical projection than low-pitched sounds. These various techniques are complementary. PET allows a pharmacological study of the cortex, and could be used in patients with cochlear implants. FMRI is non-invasive, and has a high spatial resolution. EEG has an excellent temporal resolution, and EEG recordings do not require major equipment or infrastructure. MEG has a better spatial resolution, with the same temporal resolution, as EEC. MEG is particularly useful in the localization of the cortical generators of middle-latency auditory evoked responses.

Expression of NMDA, AMPA and GABA(A) receptor subunit mRNAs in the rat auditory brainstem. II. Influence of intracochlear electrical stimulation

We investigated the effects of intracochlear electrical stimulation (ICES) on auditory pathways of neonatal rat deafened by daily amikacin injections. Expression of mRNAs encoding ionotropic glutamate receptor subunits such as alpha-amino-3-hydroxy-5-methyl-4-isoxazole (AMPA) and N-methyl-D-aspartate (NMDA), and gamma-aminobutyric acid type A (GABA(A)) receptor subunits was assessed by in situ hybridization in the dorsal (DCN) and the ventral cochlear nucleus (VCN) and in the central nucleus of the inferior colliculus (CNIC). After 15 days of daily unilateral ICES, the expressions of NR1, NR2b and NR2c subunits of NMDA receptor, that of GluRA, B, C, D flop isoforms of AMPA receptor and that of some GABA(A) subunits (alpha1, beta1, gamma1, gamma2) were increased bilaterally in the DCN, VCN and the CNIC. These changes last over a week after stimulation for only NR1 and NR2c. These modifications might be related to long lasting synaptic plasticity of brainstem auditory pathways. As far as analogy to deaf children can be made, early electrical stimulation might be of interest to maintain neuronal networks.

Mismatch negativity: a tool for the assessment of stimuli discrimination in cochlear implant subjects

OBJECTIVES

The performance of cochlear implants varies among users. This variability may be due to the ability to process auditory information. The mismatch negativity should provide an index of discrimination in cochlear implantees (Kraus N, McGee T, Carrell T, Sharma A. Neurophysiologic bases of speech discrimination. Ear Hear. 1995;16:19-37). Our aim was to analyze MMN in cochlear implant (Digisonic) subjects to assess electrode discrimination and to study the relationship between MMN and speech performance.

METHODS

The mismatch was determined by stimulating three pairs of different electrodes. Two sessions were performed with both standard and deviant stimuli reversed. Speech recognition abilities were evaluated using 4 speech tests. The statistics included the results of 6 subjects. They indicated that MMN may be obtained when stimulating two different electrodes. A difference occurred between standard and deviant stimuli within a session but also when the response to the deviant stimulus was compared to the response of the same stimulus in a standard condition, validating the discrimination process. MMN latency was about 140 ms, and amplitude about -2.8 microV. No differences were shown with respect to electrode spacing. No relationship between MMN and speech performance was found. A clinical application of this method might be to assess the auditory processing of electrical stimuli in congenitally deaf subjects at the pre-implantation stage.

[Therapy techniques of deafness]

Techniques for treating hearing loss comprise surgery, hearing aids and rehabilitation. Medical treatments are devolved to the correction of the cause of the loss of hearing, essentially infection. In hearing loss, surgery is routinely used to repair the consequences of chronic infection and of trauma. It is also used for treatment of otospongiosis. It is used to place vibratory or electric prostheses, which will increase the quality of indications for surgery. For instance, cochlear implants can be used in profound or total, bilateral hearing loss. In parallel, the quality and the miniaturisation of external auditory devices is improving. Rehabilitation, by helping to reconstitute missing factors, comprises a third technique of treatment of hearing loss.

[A new application of extraoral implants: the permanent percutaneous electrical connection. Apropos a case]

The principle of EOI is an implant fixed to the bone supporting a percutaneous abutment. Placed through the skin, the abutment allows a permanent communication between inside and outside of the organism. A rigorous very precise surgical protocol has allowed good results of the technique for over 20 years and shown the reliability of this two-piece device. This surgical protocol and device concept have been used by the authors to design a percutaneous electrical connector experimented in a rabbit model since 1996. A percutaneous electrical connector called PEP (percutaneous electrical plug) directly steming from the Sweden and German extra oral implants as been design for human applications. Authors describe the surgical placement and loading of there first PEP, under Huriet law, in an otologic application: the treatment of sever, drug-resistant tinnitus by electrical stimulation of the internal ear. The anatomical implantation area of these new extra-oral implants is retro-auricular. So the implants placements should be realized by ENT and maxillo-facial surgeons.

Cochlear implant performance and electrically-evoked auditory brain-stem response characteristics

OBJECTIVES

The purpose of this study was to find a correlation between cochlear implant performances in phoneme discrimination and activity of the brain-stem.

METHODS

Electrically-evoked auditory brain-stem responses (EABRs) and speech recognition performances were measured in 17 patients implanted with an MXM Digisonic DX10 cochlear implant. Speech recognition performances without lip-reading were tested using lists of isolated French words containing 3 phonemes.

RESULTS

The results indicated statistically significant correlations between phoneme correct-identification scores and the following EABR variables: wave V latency, wave II-V latency interval and wave III-V latency interval. These results, indicate that up to about 48% of the variance in isolated word recognition without lip-reading can be accounted for by EABR variables.

CONCLUSION

The quality of brain-stem functioning influences central processes in phoneme discrimination.

[Dilator muscles of the pharynx and their implication in the sleep apnea syndrome of obstructive type. Review of the literature]

Pathophysiology of the obstructive sleep apnea syndrome shows three components: intra and peripharyngeal obstacles, excessive pharyngeal wall compliance and upper airway dilator muscle dysfunction. The intent of this paper is to provide an overview of the anatomy, histology, physiology and pathophysiology of the upper airway dilator muscles based on previously published articles. The upper airway dilator muscles can be separated in three different systems, main and accessory dilators, local and regional. They act in synergy. Their contraction occurs at the beginning of inspiration, thus maintaining opened the pharyngeal lumen through inspiration. Their action is modulated by several chemo or physical stimuli. In some apneic patients, these muscles demonstrate a dysfunction: hyperactivity during wakefulness, electromyogram wave amplitude reduced, delayed contraction during sleep and abnormal response to stimuli. This dysfunction might be due to neuromuscular histological abnormalities, a "fatigue" phenomenon or a central nervous command abnormality. Current explorations underlining an upper airway dilator muscle dysfunction will enable practitioners to decide which treatment is best and understand therapeutical failures; it will also help develop new therapeutical techniques such as functional electrical stimulation of the hypoglossal nerve/upper airway dilator muscles.

Influence of local radiotherapy on penetration of fluconazole into human saliva

The pharmacokinetics of fluconazole (50 mg, single oral dose) in saliva and plasma were determined for five healthy subjects and five patients who underwent radiotherapy (dose, > 45 Gy over a 6-week period) in the salivary gland area and suffered from oropharyngeal candidiasis. Saliva was collected after electrical stimulation. Fluconazole was measured by liquid chromatography. From healthy volunteers and patients, saliva and plasma were sampled from 0 to 24 h. Although fluconazole penetration kinetics were significantly slowed down in irradiated patients, saliva concentrations of fluconazole were higher than those in the plasma, except at 1 h. In the postdistribution phase, the saliva/plasma concentration ratio was in the range of 1.2 to 1.4, and there was no significant difference between healthy subjects and patients. The saliva concentration of fluconazole was over 1 mg/liter throughout the entire interval 2 to 24 h after drug intake. From these results, the clinical efficacy of fluconazole for oropharyngeal candidiasis is not expected to be less than that in subjects with normal salivary glands, provided that salivary secretion remains.

Transient hypocalcemia after thyroidectomy

The causes of transient hypocalcemia after thyroid surgery are not fully understood. In 95 consecutive patients undergoing total thyroidectomy (n = 30), subtotal thyroidectomy (n = 14), or hemithyroidectomy (n = 51), we serially measured total calcium, parathyroid hormone (PTH), and proteins before surgery and 6, 24, 48, 72, and 96 hours after surgery, and we calculated the corresponding ionized calcium levels. In the whole population, there was a statistically significant decrease of PTH, total calcium, and proteins at nearly every time of blood withdrawal, when compared with the preoperative levels. The PTH decreased earlier and total calcium levels were significantly lower after total thyroidectomy than after hemithyroidectomy (at 48, 72, and 96 hours). Ten patients had on 2 occasions serum calcium levels below or equal to 2 mmol/L and were defined as having severe hypocalcemia. Severe hypocalcemia was found in 8 patients after total thyroidectomy, compared with 2 after hemithyroidectomy (p < .05), and was present in 3 of the 5 patients with thyroid carcinoma, compared with 7 of the 90 patients with nonmalignant thyroid diseases (p < .01). Despite careful preservation of the parathyroid glands and their blood supply, thyroidectomy was often followed by transient hypocalcemia, the determinants of which are hypoparathyroidism and hemodilution. No patients had persistent symptoms of hypocalcemia from 2 to 3 months after surgery.

Middle ear adenoma. A tumor displaying mucinous and neuroendocrine differentiation

Middle ear adenoma (MEA) is a distinctive, rare entity that appears to be derived from the lining epithelium of the middle ear mucosa. We report four cases of MEA displaying the typical histologic growth pattern. Two distinct tumor cell immunophenotypes were identified in all cases; the first type exhibited positivity with anti-epithelial membrane antigen and anti-keratin antibodies, and the second type showed immunoreactivity with anti-keratin, anti-vimentin, and anti-neuron-specific enolase antibodies. Ultrastructural studies revealed bidirectional mucinous and neuroendocrine differentiation, demonstrated by the presence of two distinct cell types containing apically located mucous granules and basally concentrated neuroendocrine granules, respectively. The presence of neuroendocrine differentiation was supported by the immunohistochemical detection of vasoactive intestinal polypeptide in the tumor cells in one case and neuron-specific enolase in three cases. These findings suggest that the potential for mixed mucinous/neuroendocrine differentiation described in other endodermally derived tumors also exists in middle ear mucosa. We also believe that the rare lesions diagnosed as primary carcinoid tumors of the middle ear might in fact be MEA with predominant or only neuroendocrine differentiation. The clinical course of our four cases and our review of the pertinent literature confirm the benign nature of MEA and indicate that these tumors should be treated by complete local excision without additional therapy.

[Caustic digestive stenosis involving the hypopharynx. Esophagopharyngoplasty using a right ileocolic graft]

The authors describe an oesophago-laryngoplastic technique using a retrosternal ileocolic graft and involving anterior pharyngotomy above the hyoid bone. The technique was applied to five cases of major destructive lesions of the hypopharynx with fibrotic stenosis, due to severe burns of the upper digestive tract by ingestion of caustic substances. Continuity between the oral cavity and the digestive tract was re-established in all cases.

[Pseudocaloric nystagmus (author's transl)]

The effect of bithermal caloric tests on the velocity of spontaneous nystagmus was retrospectively studied in 107 patients with unilateral vestibular areflexia. In 35 out of 107 patients, the velocity or pre-test nystagmus was not lower than 15 jerks in 30 seconds. In our series, spontaneous nystagmus before the caloric test was mostly seen in patients with neuritis or sudden deafness, and as a rule, the tests had little effect on the velocity of the nystagmus. In 7 out of 10 cases of areflexic Mènière's disease spontaneous nystagmus was revealed by caloric tests. Spontaneous pre-test nystagmus was present in 6 out of 29 cases of neurinoma; its velocity was always reduced during the caloric tests. In 14 out of 25 cases of head injury, areflexia was usually compensated. Vestibular compensation can now be defined as the absence of vertigo, of spontaneous nystagmus before and after caloric tests and directional predominance.

[Respiratory obstacle and gastro-oesophageal reflux. Pathogenic link (author's transl)]

The finding of the frequent association in the infant of endothoracic tracheal compression and of GOR leads to discussion of their pathogenic link. In cases of endothoracic compression, manometric recording demonstrates the presence of an inversion of intragastric pressures with expiratory hyperpressure and a decrease in anti-reflux gradient. These data represent an argument in favour of medical anti-reflux treatment following discovery during endoscopic investigations for chronic or recurrent bronchopneumonia of the association of tracheal compression and gastrooesophageal reflux. Manometry should make it possible, where medical treatment proves unsatisfactory, to differentiate those cases where anti-reflux surgery is justified and those requiring a decompression procedure.

[Evoked brain stem potentials. Study of their adaptation in multiple sclerosis]

This study of the Brainstem evoked Response has been done to try to find the exact location of neurologic disorders. The authors wanted to see if there were differences between normal subjects and patients with multilocular sclerosis, when the auditory stimulus in increasing from 10 pps to 50 pps. From 15 normal subjects (30 ears) the results have been compared to those obtained from 6 patients. The findings were: -- there is no adaptation phenomenon in the Brainstem (the conduction time in the Brainstem is absolutely constant). -- there is an adaptation which occurs before the first peak, happening later at 50 pps than at 10 pps. -- in the multilocular sclerosis the findings were: augmentation of the peak to peak delay no synchronisation of the peaks so that is very difficult to recognize each peaks. And the peaks are easier to recognize at 50 pps than at 10 pps which fact unexpectable. This dyssynchronisation at the compression and rarefaction click is for the authors an important factor for the multilocular sclerosis diagnosis.

[Follow-up surgery for carcinoma of the tonsil (author's transl)]

This study involves the frequency, techniques and results of follow-up surgery for carcinoma of the tonsil treated by transcutaneous radiotherapy. Local or lymph node failures affect 65% of patients treated by radiation. Follow-up surgery was used in 86% of these failures. After reviewing the various techniques and their oncological results, the authors discuss the best timing for follow-up surgery. They compar their results of surgery in the case of sub-total treatment, surgery for recurrences and routine surgery two months after the end of transcutaneous irradiation. The results are in favour of routine surgery. If it is accepted, since this point is open to discussion, that radiotherapy remains the appropriate initial, and sometimes adequate, treatment for carcinoma of the tonsil, the frequency of local and lymph node recurrences should lead to the indication, in certain cases, for complementary surgical therapy. This routine additional surgical treatment should be discussed in the context of the initial protocol of the treatment of a carcinoma of the tonsil.