Mastoid: The posterior part of the temporal bone. It is a projection of the petrous bone.Mastoiditis: Inflammation of the honeycomb-like MASTOID BONE in the skull just behind the ear. It is usually a complication of OTITIS MEDIA.Cholesteatoma, Middle Ear: A mass of KERATIN-producing squamous EPITHELIUM that resembles an inverted (suck-in) bag of skin in the MIDDLE EAR. It arises from the eardrum (TYMPANIC MEMBRANE) and grows into the MIDDLE EAR causing erosion of EAR OSSICLES and MASTOID that contains the INNER EAR.Otologic Surgical Procedures: Surgery performed on the external, middle, or internal ear.Ear, Middle: The space and structures directly internal to the TYMPANIC MEMBRANE and external to the inner ear (LABYRINTH). Its major components include the AUDITORY OSSICLES and the EUSTACHIAN TUBE that connects the cavity of middle ear (tympanic cavity) to the upper part of the throat.Ear Canal: The narrow passage way that conducts the sound collected by the EAR AURICLE to the TYMPANIC MEMBRANE.Temporal Bone: Either of a pair of compound bones forming the lateral (left and right) surfaces and base of the skull which contains the organs of hearing. It is a large bone formed by the fusion of parts: the squamous (the flattened anterior-superior part), the tympanic (the curved anterior-inferior part), the mastoid (the irregular posterior portion), and the petrous (the part at the base of the skull).Vestibular Neuronitis: Idiopathic inflammation of the VESTIBULAR NERVE, characterized clinically by the acute or subacute onset of VERTIGO; NAUSEA; and imbalance. The COCHLEAR NERVE is typically spared and HEARING LOSS and TINNITUS do not usually occur. Symptoms usually resolve over a period of days to weeks. (Adams et al., Principles of Neurology, 6th ed, p304)Caloric Tests: Elicitation of a rotatory nystagmus by stimulating the semicircular canals with water or air which is above or below body temperature. In warm caloric stimulation a rotatory nystagmus is developed toward the side of the stimulated ear; in cold, away from the stimulated side. Absence of nystagmus indicates the labyrinth is not functioning.Ear Diseases: Pathological processes of the ear, the hearing, and the equilibrium system of the body.Cholesteatoma: A non-neoplastic mass of keratin-producing squamous EPITHELIUM, frequently occurring in the MENINGES; bones of the skull, and most commonly in the MIDDLE EAR and MASTOID region. Cholesteatoma can be congenital or acquired. Cholesteatoma is not a tumor nor is it associated with high CHOLESTEROL.Dysgeusia: A condition characterized by alterations of the sense of taste which may range from mild to severe, including gross distortions of taste quality.Tympanoplasty: Surgical reconstruction of the hearing mechanism of the middle ear, with restoration of the drum membrane to protect the round window from sound pressure, and establishment of ossicular continuity between the tympanic membrane and the oval window. (Dorland, 28th ed.)Autografts: Transplant comprised of an individual's own tissue, transferred from one part of the body to another.Osteoblastoma: A benign, painful, tumor of bone characterized by the formation of osteoid tissue, primitive bone and calcified tissue. It occurs frequently in the spine of young persons. (From Dorland, 27th ed; Stedman, 25th ed)Lateral Sinus Thrombosis: Formation or presence of a blood clot (THROMBUS) in the LATERAL SINUSES. This condition is often associated with ear infections (OTITIS MEDIA or MASTOIDITIS) without antibiotic treatment. In developed nations, lateral sinus thrombosis can result from CRANIOCEREBRAL TRAUMA; BRAIN NEOPLASMS; NEUROSURGICAL PROCEDURES; THROMBOPHILIA; and other conditions. Clinical features include HEADACHE; VERTIGO; and increased intracranial pressure.

Noise level of drilling instruments during mastoidectomy. (1/118)

Exposure to intense noise has been identified as a potential risk in the development of hearing impairment. Social concern about excessive noise is increasing and this also extends to the operating room. A noise level study was performed in the operating room during mastoidectomy with a sound level meter and it was analyzed by a sound-analyzing program. The drilling instruments used included the Stryker, Midas, M.P.S. and Med-Next. The operator was exposed to sound levels from 69 to 83 dBA. The loudest drilling instrument was the Midas and it produced an average sound level of 83 dBA to the operator. The mean exposure time was 41 minutes during mastoidectomy. This is below the occupational noise-level regulations in Korea. However, considering that individual susceptibility to noise varies and that the otologic surgeon is repeatedly exposed to prolonged drilling noise, ear protection is recommended for the operators of high-speed drilling instruments.  (+info)

Random errors in localization of landmarks in postero-anterior cephalograms. (2/118)

The aim of the present study was to evaluate the random error in localization of the most common landmarks in postero-anterior cephalograms (PAC). The study took place at the Department of Orthodontics of Aarhus University during the period 1993-1995. The material consisted of 30 standardized PAC taken in natural head position. Five examiners had to identify 34 landmarks on each cephalogram. Subsequently, all examiners had to identify again the same 34 landmarks on one randomly selected cephalogram five times with a time interval of at least 24 hours. All landmarks were digitized, related to an X-Y co-ordinate system, and an arithmetical mean was calculated. The accuracy of digitizing was evaluated by digitizing one randomly selected cephalogram 10 times. The main findings of this study are: (1) The digitizing error is negligible compared to the errors introduced by landmark identification. (2) Each landmark has its own characteristic pattern of variance, which is very similar on both sides. (3) Significant differences in accuracy exist between the various postero-anterior landmarks. The six most accurate landmarks are mastoid left (l) and right (r), latero-orbitale (l) and (r), and antegonion (l) and (r). The six least accurate landmarks are coronoid (l) and (r), condylar (l) and (r), and mandibular foramen (l) and (r). (4) A significant difference in the accuracy of landmark identification between the five examiners was only seen for seven of the 34 landmarks. (5) No evidence was found that one examiner was consistently better/worse than the others. (6) No improvement in the accuracy was found after repeated identification, thus there seems to be no short-term 'learning process'. Refereed Paper  (+info)

Multisensory cortical signal increases and decreases during vestibular galvanic stimulation (fMRI). (3/118)

Functional magnetic resonance imaging blood-oxygenation-level-dependent (BOLD) signal increases (activations) and BOLD signal decreases ("deactivations") were compared in six healthy volunteers during galvanic vestibular (mastoid) and galvanic cutaneous (neck) stimulation in order to differentiate vestibular from ocular motor and nociceptive functions. By calculating the contrast for vestibular activation minus cutaneous activation for the group, we found activations in the anterior parts of the insula, the paramedian and dorsolateral thalamus, the putamen, the inferior parietal lobule [Brodmann area (BA) 40], the precentral gyrus (frontal eye field, BA 6), the middle frontal gyrus (prefrontal cortex, BA 46/9), the middle temporal gyrus (BA 37), the superior temporal gyrus (BA 22), and the anterior cingulate gyrus (BA 32) as well as in both cerebellar hemispheres. These activations can be attributed to multisensory vestibular and ocular motor functions. Single-subject analysis in addition showed distinctly nonoverlapping activations in the posterior insula, which corresponds to the parieto-insular vestibular cortex in the monkey. During vestibular stimulation, there was also a significant signal decrease in the visual cortex (BA 18, 19), which spared BA 17. A different "deactivation" was found during cutaneous stimulation; it included upper parieto-occipital areas in the middle temporal and occipital gyri (BA 19/39/18). Under both stimulation conditions, there were signal decreases in the somatosensory cortex (BA 2/3/4). Stimulus-dependent, inhibitory vestibular-visual, and nociceptive-somatosensory interactions may be functionally significant for processing perception and sensorimotor control.  (+info)

Unexpected reflex response to transmastoid stimulation in human subjects during near-maximal effort. (4/118)

1. In human subjects, a high-voltage electrical pulse between electrodes fixed over the mastoid processes activates descending tract axons at the level of the cervico-medullary junction to produce motor responses (cevicomedullary evoked responses; CMEPs) in the biceps brachii and brachioradialis muscles. 2. During isometric maximal voluntary contractions (MVCs) of the elbow flexors, CMEPs in the biceps brachii and brachioradialis muscles are sometimes followed by a second compound muscle action potential. This response can be observed in single trials (amplitude of up to 60 % of the maximal M wave) and follows the CMEP by about 16 ms in both muscles. The response only occurs during very strong voluntary contractions. 3. The second response following transmastoid stimulation appears with stimulation intensities that are at the threshold for evoking a CMEP in the contracting muscles. The response grows with increasing stimulus intensity, but then decreases in amplitude and finally disappears at high stimulation intensities. 4. A single stimulus to the brachial plexus during MVCs can also elicit a second response (following the M wave) in the biceps brachii and brachioradialis muscles. The latency of this response is 3-4 ms longer than that of the second response observed following transmastoid stimulation. This difference in latency is consistent with a reflex response to stimulation of large-diameter afferents. 5. The amplitude of the second response to transmastoid stimulation can be reduced by appropriately timed subthreshold transcranial magnetic stimuli. This result is consistent with intracortical inhibition of the response. 6. We suggest that transmastoid stimulation can elicit a large transcortical reflex response in the biceps brachii and brachioradialis muscles. The response travels via the motor cortex but is only apparent during near-maximal voluntary efforts.  (+info)

Mastoid air sinus abnormalities associated with lateral venous sinus thrombosis: cause or consequence? (5/118)

BACKGROUND: Mastoiditis is a known cause of lateral venous sinus thrombosis (LST). We have encountered patients with LST associated with mastoid abnormality on MRI without any clinical signs of infection; the significance of these abnormalities is uncertain. This study examines the relationship of LST and mastoid air sinus abnormalities systematically. SUMMARY OF REPORT: We performed a retrospective clinical and radiological review of a series of 26 patients with cerebral venous thrombosis. Mastoid abnormalities were detected ipsilateral to 9 of 23 thrombosed lateral sinuses (39%) and 0 of 29 unaffected lateral sinuses (P<0.001). No patient had clinical evidence of mastoiditis. Eight of 9 patients with mastoid abnormalities were treated without antibiotics; all made uneventful clinical recoveries. Repeated MRI in 1 patient revealed reversal of the mastoid changes. CONCLUSIONS: The mastoid changes observed are likely to be due to venous congestion as a consequence of LST, not mastoiditis.  (+info)

Comparison of human ocular torsion patterns during natural and galvanic vestibular stimulation. (6/118)

Galvanic vestibular stimulation (GVS) is reported to induce interindividually variable tonic ocular torsion (OT) and superimposed torsional nystagmus. It has been proposed that the tonic component results from the activation of otolith afferents. We tested our hypothesis that both the tonic and the phasic OT are mainly due to semicircular canal (SCC) stimulation by examining whether the OT patterns elicited by GVS can be reproduced by pure SCC stimulations. Using videooculography we measured the OT of six healthy subjects while two different stimuli with a duration of 20 s were applied: 1) transmastoidal GVS steps of 2 mA with the head in a pitched nose-down position and 2) angular head rotations around a combined roll-yaw axis parallel to the gravity vector with the head in the same position. The stimulation profile was individually scaled to match the nystagmus properties from GVS and consisted of a sustained velocity step of 4-12 degrees /s on which a velocity ramp of 0.67-2 degrees /s(2) was superimposed. Since blinks were reported to induce transient torsional eye movements, the subjects were also asked to blink once 10 s after stimulus onset. Analysis of torsional eye movements under both conditions revealed no significant differences. Thus we conclude that both the tonic and the phasic OT responses to GVS can be reproduced by pure rotational stimulations and that the OT-related effects of GVS on SCC afferents are similar to natural stimulations at small amplitudes.  (+info)

Diffusion-weighted imaging for differentiating recurrent cholesteatoma from granulation tissue after mastoidectomy: case report. (7/118)

Identification of recurrent cholesteatoma and differentiation from postoperative granulation tissue is important in a patient who has undergone mastoidectomy for cholesteatoma. We describe the diffusion-weighted imaging findings and apparent diffusion coefficient values in a case of recurrent cholesteatoma. This case suggests possible differentiation of cholesteatoma from granulation tissue on the basis of diffusion-weighted imaging findings.  (+info)

Vibration-induced ocular torsion and nystagmus after unilateral vestibular deafferentation. (8/118)

Vibration is an excitatory stimulus for both vestibular and proprioceptive afferents. Vibration applied either to the skull or to the neck muscles of subjects after unilateral vestibular deafferentation induces nystagmus and a shift of the subjective visual horizontal. Previous studies have ascribed these effects to vibratory stimulation of neck muscle proprioceptors. Using scleral search coils, we recorded three-dimensional eye movements during unilateral 92 Hz vibration of the mastoid bone or of the sternocleidomastoid (SCM) muscle in 18 subjects with chronic unilateral vestibular deficits after vestibular neurectomy or neuro-labyrinthitis. Nine subjects had lost function of all three semicircular canals (SSCs) on one side, and the other nine had lost function of only the anterior and lateral SSCs. Vibration of the mastoid bone or of the SCM muscle on either side induced an ipsilesional tonic shift of torsional eye position of up to 6.5 degrees during visual fixation, as well as a nystagmus with horizontal, vertical and torsional components in darkness. Subjects who had lost function of all three SSCs on one side showed a larger shift in ocular torsion in response to SCM vibration than did subjects who had lost function of only two SSCs. The difference between ocular torsion produced by ipsilesional muscle or bone vibration was not significantly different from that produced by contralesional bone or muscle vibration. The vibration-induced nystagmus rotation axis tended to align with the pitch (y) axis of the head in subjects who had lost only anterior and lateral SSC function, and with the roll (x) axis of the head in subjects who had lost function of all three SSCs. We propose that the previously described vibration-induced shift of the subjective visual horizontal can be explained by the vibration-induced ocular torsion, and that the magnitude of ocular torsion is related to the extent of the unilateral vestibular deficit. While altered proprioceptive inputs from neck muscles might be important in the mechanism of vibration-induced ocular torsion and nystagmus after unilateral vestibular deafferentation, vibratory stimulation of vestibular receptors in the intact labyrinth also appears to have an important role.  (+info)

  • The mastoid part has an outer rough surface that provides attachment to occipitalis and auricularis posterior muscles. (radiopaedia.org)
  • Hearing preservation is not the primary object behind mastoid surgery but rather the number one goal is to get rid of the infection and/or cholesteatoma, which is of potential danger to the patient. (nwfacemedical.com)
  • Patient, Intervention and Result: We treated surgically with success a 14-year-old boy with osteoma of mastoid process, obstructing the external auditory canal of the left ear and causing conductive hearing loss. (scirp.org)
  • While we have more sophisticated radiological techniques of examination of the mastoids, the ability to read an X-ray of mastoid is a must for the undergraduate students of the medicine. (epomedicine.com)
  • We performed a macroscopic, radiographic, and microscopic study of pneumatization patterns in 151 mastoid processes of individuals from an early-medieval cemetery in Germany, with emphasis on the architecture of the nonpneumatized portion of hypocellular mastoid processes. (docme.ru)
  • The observed variability in the degree of pneumatization of the mastoid process raises the question of whether a poorly developed or missing mastoid air-cell system can be viewed as a pathological condition (e.g. (docme.ru)
  • Differential diagnosis of mastoid hypocellularity in human skeletal remains. (docme.ru)
  • In another patient who presented with left temporal lobe hemorrhage, both the mastoid abnormality and the diagnosis of CVT were initially overlooked ( Figure 2 ). (ahajournals.org)
  • The results from this structural tensor analysis suggest these microchannels to potentially be part of a more complex framework, which hypothetically would provide a separate blood supply for the mucosa lining the mastoid air cell system.The knowledge gained from analysing the micro-channels as locally providing blood to the mucosa, led to the consideration of how inflammation of the mucosa could impact the pneumatization of the mastoid air cell system. (avhandlingar.se)
  • The observed variability in the degree of pneumatization of the mastoid process raises the question of whether a poorly developed or missing mastoid air-cell system can be viewed as a pathological condition (e.g. (docme.ru)
  • Contrast Enhanced Computerized Tomography (CECT) Scan of the Mastoid bones is a diagnostic procedure where rotating beams of X-rays are used to create cross sectional images of the inner ear. (1mg.com)
  • Soft tissue densities in the normally air filled mastoid, middle ear and sinus cavities indicates there is some type of chronic, long term inflammation in those areas. (healthtap.com)
  • From both quantitative and qualitative statistics, it was possible to map the clusters based on pre-defined regions already described in the literature, which opened the door for new hypotheses concerning the effect of mucosal inflammation on the mastoid pneumatization.Last but not least, discovery of other structures, previously unreported in the literature, were also visually observed and briefly discussed in this thesis. (avhandlingar.se)
  • The radiologist is detecting inflammation in the mastoid and the middle ear. (healthtap.com)
  • In this article we report the case of a patient with Cystic Adenoid Carcinoma of the external auditory meatus with mastoid involvement that presented peripheral facial paralysis. (arquivosdeorl.org.br)
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