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T Lenarz

Publications and source records attributed to T Lenarz.

At least 181 records · Page 10Linked to original sources
PubMed1994

[Effect of anesthesia on the intraoperative elicited stapedius reflex].

Evaluation of the intraoperative electrically evoked stapedius reflexes during cochlear implant surgery has two purposes: (1) The functioning of the device and the peripheral auditory pathways can be proven immediately and (2) The data of reflex threshold can be used for the prediction of later threshold (T)- and maximum comfortable (C) levels. This is especially useful for the later fitting of the speech processor in very young children. When trying to use the stapedius reflex data for the prediction of T- and C-levels it must be considered that during surgery the drugs used for general anaesthesia influence the values of the stapedius reflex. Depending on the drug, the stapedius reflex threshold can be increased or the reflex can even be totally blocked. This is not only due to relaxants but also to anaesthetics. To investigate this influence we first determined the acoustically evoked stapedius reflex threshold in normal hearing adults under general anaesthesia with 7 different anaesthetics without additional relaxation. It was found that especially with Dormicum and Brevimytal the stapedius threshold increased only very lightly or did not change at all. In a second investigation the electrically evoked stapedius reflex thresholds were obtained in adults who underwent a cochlear implant surgery using the same anaesthetics for anaesthesia. The intraoperatively evaluated reflex data were compared with postoperatively obtained data. It was found that both reflex thresholds were similar if evaluated in Dormicum or Brevimytal anaesthesia. This suggests that only with the use of the right anaesthetics the data of the electrically evoked stapedius reflex obtained intraoperatively can be used for predicting T- and C-levels.

Anesthesia, General↗
PubMed1994

[Primary clinical manifestation of tuberculosis as an incidental finding in the head and neck area].

Between 1988 and 1992 12 patients were seen who had findings leading subsequently to the diagnosis of tuberculosis. The average age was 50 with a range from 22 to 88 years. Women outnumbered the male by 10 to 2 cases. The number of German patients equalled that of foreign patients. Tuberculosis was mainly localised in the cervical lymph nodes in 6 cases. One patient was seen with manifestation in each case at the palate, larynx, nasopharynx, cheek, parotis and middle ear. Diagnosis was made by histology alone six times, by evidence of acid-fast rods once and by both means in 5 cases. Preoperatively a malignant neoplasm was suspected in most patients, and neither CT nor ultrasound revealed a hint to tuberculosis. Tine-test was positive in all patients. Only in 3 patients was there an evidence of acid-fast rods in sputum and gastric juice. None of them suffered from AIDS. They were treated by combination of rifampicin, ethambutol, isoniazid and partially with pyrazinamide. No relapse was observed to date.

Adult↗
PubMed1994

[A clinically relevant variation of the superior thyroid artery].

Usually the superior thyroid artery is a branch of the external carotid artery. During a functional neck dissection in order to remove a metastasis of a tongue cancer we observed a variation of the origin of the vessel that was interesting from the surgeon's point of view. The artery rose from the A. carotis communis 3.5 cm below the bifurcation of the common carotid artery. Normally in this region no vessels leave the common carotid artery and therefore the knowledge of such variations is important for the exact identification of the neck vessels during surgery to avoid a fatal mix-up with the internal carotid artery.

Arteries↗
PubMed1994

[Noninvasive assessment of intracochlear pressure and patency of the cochlear aqueduct in normal probands with TMD (tympanic membrane displacement) analysis].

The intracochlear pressure cannot yet be evaluated in patients with certain audiological neuro-otological diseases. However, it seems to be of importance in the diagnosis and pathogenesis of Ménière's disease and related disorders. The present paper is aimed at introducing a setup to indirectly assess intracochlear and intracranial pressure changes and the design and philosophy of this technique. It is possible to describe a normal range of the measured values in healthy controls although large interindividual variations occur. In addition, the positional changes of the registered parameters enable assessment of the patency of the cochlear aquaeduct. This seems to be important in some diseases, such as stapes gusher.

Acoustic Impedance Tests↗
PubMed1994

Intraoperative facial nerve monitoring in the surgery of cerebellopontine angle tumors: improved preservation of nerve function.

The surgery of cerebellopontine angle tumors has shown remarkable progress over the last 20 years due to improved microsurgical techniques. However, the dissection of the facial nerve may lead to postoperative paresis as the result of the surgical trauma and the disruption of blood supply over a large distance. The functional status of the nerve can be intraoperatively monitored by means of intramuscular electromyography of facial muscles and direct electrical stimulation. In this study, the impact of monitoring techniques on the preservation of facial function was evaluated by comparing monitored (n = 30) and unmonitored (n = 34) patients. Both groups were comparable with regard to the size of the tumor, the surgical approach and the duration of operation. All patients were operated by the same surgeon (T.L.) either via the middle fossa or the translabyrinthine approach. The EMG was recorded with needle electrodes from the orbicularis oris and oculi muscles. For electrical stimulation, bipolar forcep electrodes were used delivering rectangular, constant current pulses of 100 microseconds duration and a current strength between 0.05 and 0.8 mA. The mechanically or thermally elicited activity by drilling, direct manipulation or coagulation consisted of bursts and trains which are signs of minor nerve impairment. Their occurrence can lead to a modified surgical technique with a more precise preparation around and at the facial nerve. The immediate postoperative nerve function was normal or showed only a minor impairment (classes I and II according to House and Brackmann) in 87% of the monitored as compared with 74% of the unmonitored patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebellopontine Angle↗
PubMed1993

Neural mechanisms of tinnitus.

The theoretical concepts underlying the neural origin of tinnitus are outlined. Several neurophysiological models are reviewed critically and the impact of the pathological ensemble spontaneous activity of the auditory system for the diagnosis and therapy of tinnitus is described in more detail.

Animals↗
PubMed1993

[Langerhans cell histiocytosis of the tonsil].

Langerhans cell histiocytosis (histiocytosis X) of the tonsil is a rare disorder of histiocytic proliferation with a broad spectrum of clinical symptoms. We report on a case of a solitary histiocytosis of a unilateral tonsillar palatine. To exclude a mesenchymal tumour a 32-year old male with a hyperplasia of the left tonsil underwent surgery. The histopathological examination revealed a solitary infiltration of Langerhans cells. We found a morphologically remarkable intraepithelial hyperplasia of Langerhans cells (S-100 protein positive) on contrast to the opposite side. The CT scans of the neck, thorax, abdomen and pelvis and the bone marrow puncture could not detect any further manifestation of the disease. Therefore, we refrained from systemic therapy. Up to now the patient is without any relapse of the disease for a period of 16 months.

Adult↗
PubMed1993

[Arteriovenous hemangioma of the facial nerve. Case report and review].

Hemangioma of the facial nerve is a rare cause for sensorineural hearing loss. Such was found in a 50-year-old patient with a history of slowly progressive, unilateral deafness. Pure-tone audiogram showed only residual hearing in the left ear. A stapedial reflex could not be elicited, nor could brainstem evoked potentials be recorded. Cranial CT showed a widened internal auditory meatus, while a Gadolinium MRI revealed an enhancing process of the left cerebellopontine angle. Via a translabyrinthine approach a tumor of the facial nerve was found and resected completely. Histopathologic examination demonstrated an arteriovenous hemangioma.

Cranial Nerve Neoplasms↗
PubMed1993

[Retrocochlear hearing disorders].

Sensorineural hearing loss is a common disorder that results from damage to the inner ear in over 95% of all cases; therefore, retrocochlear hearing disorders are rare and cannot be differentiated from sensory losses by clinical symptoms alone. Associated vestibular and other neurotological symptoms must lead to appropriate diagnostic procedures. Besides audiological and neurotological tests, e.g. auditory-evoked potentials, otoacoustic emissions or electronystagmography, modern imaging methods are the most valuable tools to detect tumorous, vascular and inflammatory processes. Acoustic neuromas, which are the most frequent causes, require otoneurosurgery with the attempt to preserve hearing and facial nerve function. Multiple sclerosis and vascular lesions of the vertebral arteries or their branches require an interdisciplinary approach. Due to recent advances in diagnostics, imaging and management, retrocochlear disorders have gained much interest from otologists in the last few years. They provide new insight into the physiology and pathophysiology of hearing.

Brain Stem↗
PubMed1993

[An active endocrine glomus tumor (paraganglioma) as a cause of tinnitus and hypertension].

A glomus jugulare tumor arises from the glomus bodies located in the adventitia of the dome of the jugular bulb. A glomus tumor has the same microscopic appearance as a carotid body tumor. The present report includes the extraordinary clinical and morphological features of a catecholamine-secreting glomus tumor (paraganglioma) in a 41-year-old woman. The patient presented with uncontrollable hypertension und pulsatile tinnitus. The diagnostic and therapeutic management is reported, including MIBG scintigraphy, computed tomography, magnetic resonance imaging, embolization, angiography, selective venous sampling studies and control of hypertension. After cardiovascular stabilization and tumor embolization, the tumor was removed surgically, with subsequent resolution of hypertension. While light microscopical analysis showed a classical glomus tumor, ultrastructural analysis revealed particular details of the tumor cells.

Adult↗
PubMed1992

Intraoperative monitoring by transtympanic electrocochleography and brainstem electrical response audiometry in acoustic neuroma surgery.

The preservation of hearing is a major aim of contemporary temporal bone surgery. Our present findings demonstrate that intraoperative monitoring is a key method for attaining serviceable postoperative hearing after the removal of an acoustic neuroma. Both electrocochleography (ECoG) and brainstem electrical response audiometry were performed in 96 patients operated on for acoustic neuromas. The specificity of the different monitoring methods was affected by surgical manipulations in addition to such non-specific influences as CSF drainage, core body temperature and anesthesia. In the present study ECoG was found to be more reliable in assessing the intra- and postoperative course with respect to the preservation of cochlear function.

Audiometry, Evoked Response↗
PubMed1992

[Reconstructions in the head and neck area using a free latissimus dorsi flap].

Deep defects of the head and neck involving different layers require plastic reconstruction with bulky flaps. We present our experience in the use of the free latissimus dorsi flap in head and neck reconstruction and point out its advantages to the pedicled latissimus dorsi flap. The latissimus dorsi flap not only is useful for conturing the head and neck but also to fill out large cavities due to operation. It further can be used for reconstruction of the oral cavity and pharynx after extended tumour excision.

Head and Neck Neoplasms↗
PubMed1992

[Evoked otoacoustic emissions and their modification by contralateral acoustic stimulation].

The active vibration of the basilar membrane as well as evoked otoacoustic emissions (EOAE) are probably based on the motile properties of cochlear outer hair cells (OHC). In the present study we examined the effects of contralateral acoustic stimulation on ipsilateral EOAE and thereby the active cochlear micromechanics. Contralateral white noise with intensities below 30 dB HL enhanced the EOAE amplitude, whereas higher sound levels reduced the evoked acoustic emissions. Similar effects of contralateral acoustic stimuli on ipsilateral EOAE were observed in patients with a conductive hearing loss. However, the required sound levels were higher compared to probands with normal hearing. In controls with unilateral deaf patients white noise up to 60 dB HL did not alter the EOAE amplitude. We concluded, that in patients with normal hearing or unilateral conductive hearing loss, effects of contralateral acoustic stimulation on evoked ipsilateral sound emissions may be due to the activation of crossed olivo-cochlear efferents reaching the OHCs.

Acoustic Stimulation↗
PubMed1992

[Glomus tumors of the temporal bone--surgical concept and results].

Between 1985 and 1991, 36 patients with glomus tumors of the temporal bone were operated. More than 60% of the patients presented with an advanced disease (Class C and D) according to the initially discret and slowly progressive clinical signs. Pulsatile tinnitus, hearing loss and paresis of the lower cranial nerves IV to XII were most often found. The management of the patients requires a complete surgical resection with different approaches depending on the extension of the tumor. High resolution CT of the temporal bone and selective angiography of the tumor feeding vessels proved as reliable and necessary imaging tools to determine the size of the tumor and thereby the surgical procedure. Class A tumors (n = 4) were completely resected by an enaural transmeatal approach. Class B tumors (n = 10) were removed completely in all cases by a combined transmeatal-transmastoid approach. A conductive hearing loss in 2 cases and transient facial paresis in one case were observed. Class C tumors (Glomus jugulare tumors, n = 16) required an infratemporal fossa approach type A. A complete resection was achieved in 87.5%. Class D tumors (n = 6) with intracranial extension were managed in a two stage otoneurosurgical procedure. Due to the tumor size and the required surgical procedure a higher incidence of functional lesions (combined hearing loss, vertigo, cranial nerve pareses) was observed. A facial paresis occurred in all cases but was transient in most of them. The results show that functional conservation surgery for glomus tumors of the temporal bone is only possible in Class A and B and some of the Class C tumors. This requires an early diagnosis.

Angiography, Digital Subtraction↗
PubMed1992

[Midfacial degloving: an alternative approach to the frontobasal area, the nasal cavity and the paranasal sinuses].

Midfacial degloving can be characterized as an alternative surgical approach for exposing the bony structures of the midface. In combination with transient partial osteotomies the nasal cavities, the paranasal sinuses, the pterygopalatine fossa and the posterior parts of the anterior skull base are easily accessible. Using an intercartilaginous, a transseptal and a circumvestibular incision in the nose and a vestibular incision in the oral cavity the soft tissues of the upper face are mobilized and transposed cranially up to the infraorbital rim, the nasion and the lacrimal sac. Thus one can avoid scar formations in the face. In comparison with the common visible incisions in the face a bilateral exposure of midline structures is possible. The resected bone can be easily replaced and fixed with titanium miniplates for osteosynthesis. The soft tissue glove is replaced. A correct suture technique for readaptation especially in the nasal cavity is most important to avoid a circular stenosis of the nasal aperture. Between 1986 and 1991, 40 patients with various tumors (juvenile angiofibroma, inverted papilloma, esthesioneuroblastoma, squamous cell carcinoma of the maxillary sinus, benign tumors of the pterygopalatine fossa, clivus chordoma) underwent this procedure. Neoplasms and fractures of the anterior frontal skull base, the frontal sinus, the orbital cavity and the zygoma were less accessible due to the unsatisfactory exposure of these regions. Complications and side effects were rare. In five cases, a transient paresthesia of the infraorbital nerve and a facial edema were observed. In one case, a circular stenosis of the nasal aperture required a second plastic procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1991

[Experience with electrostimulation of the acoustic nerve before cochlea implantation].

The electrical stimulation of the acoustic nerve plays an essential role in the selection of patients for cochlea implantation. The performance of a deaf ear under the conditions of electrical stimulation can be assessed by means of the pre-operative promontory test using a transtympanic needle electrode. Five components of this test were applied to 48 patients: the determination of perception threshold and upper comfortable level for pulse and burst stimulation, the pitch test, the temporal difference test and the gap detection test. The mean values emerging from these examinations may be useful as guidelines for the interpretation of individual results. A cross correlational analysis of the data was performed in order to eventually discover redundancies among the different test components. Indeed, the threshold values for pulses of a given duration are highly correlated to those for bursts of the corresponding frequency. One of these tests may therefore be eliminated for routine test purposes. Similarly, the assessment of time resolution capabilities with the temporal difference limen test yields results which show a strong correlation with those of the gap detection test.

Auditory Threshold↗