Reply to “On Cochlear Impedances and the Miscomputation of Power Gain” by Shera et al. J. Assoc. Re. Otolaryngol.

Using a scanning laser interferometer, we recently measured the volume velocity of the basilar membrane vibration in the sensitive gerbil cochlea and estimated that the cochlear power gain is ~100 at low sound pressure levels (Ren et al., Nat Commun 2:216–223, 2011a). We thank Shera et al. for recognizing the technical challenges of our experiments and appreciating the beauty of our data in their comment (Shera et al., J Assoc Res Otolaryngol (in press), 2011). These authors argue that our analysis is inappropriate, invalidating our conclusion; moreover, they suggest that our finding of a power gain of >1 could arise from a passive structure or cochlea. While our analysis and interpretation remain to be verified, they are justified according to commonly accepted assumptions and theories in cochlear mechanics. Here, we also show that the mathematical demonstration of a power gain of >1 in a passive cochlea by Shera et al. is inconsistent with our data, which show that the volume velocity and power gain decrease and become <1 as the sound level increases.     

Primary Neural Degeneration in the Guinea Pig Cochlea After Reversible Noise-Induced Threshold Shift

Recent work in mouse showed that acoustic overexposure can produce a rapid and irreversible loss of cochlear nerve peripheral terminals on inner hair cells (IHCs) and a slow degeneration of spiral ganglion cells, despite full recovery of cochlear thresholds and no loss of inner or outer hair cells (Kujawa and Liberman, J Neurosci 29:14077–14085, 2009). This contrasts with earlier ultrastructural work in guinea pig suggesting that acute noise-induced neural degeneration is followed by full regeneration of cochlear nerve terminals in the IHC area (Puel et al., Neuroreport 9:2109–2114, 1998; Pujol and Puel, Ann N Y Acad Sci 884:249–254, 1999). Here, we show that the same patterns of primary neural degeneration reported for mouse are also seen in the noise-exposed guinea pig, when IHC synapses and cochlear nerve terminals are counted 1 week post-exposure in confocal images from immunostained whole mounts and that the same slow degeneration of spiral ganglion cells occurs despite no loss of IHCs and apparent recovery of cochlear thresholds. The data cast doubt on prior claims that there is significant neural regeneration and synaptogenesis in the adult cochlea and suggest that denervation of the inner hair cell is an important sequela of “reversible” noise-induced hearing loss, which likely applies to the human ear as well.     

Transient evoked otoacoustic emissions in superior canal dehiscence syndrome

Superior semicircular canal dehiscence syndrome (SCDS) is a clinical disorder that is characterized by vertigo and oscillopsia induced by loud sounds. Transient evoked otoacoustic emissions (TEOAEs) allow to noninvasively check the integrity of the cochlea. The present study aimed at identifying cochlear stress as the result of micro alterations of the cochlear functionality due to anatomic anomaly. 11 SCDS and 10 normal individuals as control group were submitted to history taking, otological examination, basic audiologic evaluation and TEOAEs analysis using the standard wideband protocol and moving time window analysis. Although TEOAEs test results showed no statistically significant difference using the standard protocol, off-line analysis of the waveforms’ “effective duration” was statistically significantly shortened (p < 0.0001) when compared to normal ears. In conclusion, dehiscence of bone overlying the superior canal has been shown to have effects on inner ear function in terms of a third mobile window theory, thus altering pressure across cochlear partition with decrease in inner ear impedance.     

Auditory Nerve Fiber Responses to Combined Acoustic and Electric Stimulation

Persons with a prosthesis implanted in a cochlea with residual acoustic sensitivity can, in some cases, achieve better speech perception with “hybrid” stimulation than with either acoustic or electric stimulation presented alone. Such improvements may involve “across auditory-nerve fiber” processes within central nuclei of the auditory system and within-fiber interactions at the level of the auditory nerve. Our study explored acoustic–electric interactions within feline auditory nerve fibers (ANFs) so as to address two goals. First, we sought to better understand recent results that showed non-monotonic recovery of the electrically evoked compound action potential (ECAP) following acoustic masking (Nourski et al. 2007, Hear. Res. 232:87–103). We hypothesized that post-masking changes in ANF temporal properties and responsiveness (spike rate) accounted for the ECAP results. We also sought to describe, more broadly, the changes in ANF responses that result from prior acoustic stimulation. Five response properties—spike rate, latency, jitter, spike amplitude, and spontaneous activity—were examined. Post-masking reductions in spike rate, within-fiber jitter and across-fiber variance in latency were found, with the changes in temporal response properties limited to ANFs with high spontaneous rates. Thus, our results suggest how non-monotonic ECAP recovery occurs for ears with spontaneous activity, but cannot account for that pattern of recovery when there is no spontaneous activity, including the results from the presumably deafened ears used in the Nourski et al. (2007) study. Finally, during simultaneous (electric+acoustic) stimulation, the degree of electrically driven spike activity had a strong influence on spike rate, but did not affect spike jitter, which apparently was determined by the acoustic noise stimulus or spontaneous activity.     

Do Forward- and Backward-Traveling Waves Occur Within the Cochlea? Countering the Critique of Nobili et al.

The question of whether or not forward- and backward-traveling waves occur within the cochlea constitutes a long-standing controversy in cochlear mechanics recently brought to the fore by the problem of understanding otoacoustic emissions. Nobili and colleagues articulate the opposition to the traveling-wave viewpoint by arguing that wave-equation formulations of cochlear mechanics fundamentally misrepresent the hydrodynamics of the cochlea [e.g., Nobili et al. (2003) J. Assoc. Res. Otolaryngol. 4:478–494]. To correct the perceived deficiencies of the wave-equation formulation, Nobili et al. advocate an apparently altogether different approach to cochlear modeling—the so-called hydrodynamic or Greens function approach—in which cochlear responses are represented not as forward- and backward-traveling waves but as weighted sums of the motions of individual basilar membrane oscillators, each interacting with the others via forces communicated instantaneously through the cochlear fluids. In this article, we examine Nobili and colleagues arguments and conclusions while attempting to clarify the broader issues at stake. We demonstrate that the one-dimensional wave-equation formulation of cochlear hydrodynamics does not misrepresent long-range fluid coupling in the cochlea, as claimed. Indeed, we show that the long-range component of Nobili et al.s three-dimensional force propagator is identical to the hydrodynamic Greens function representing a one-dimensional tapered transmission line. Furthermore, simulations that Nobili et al. use to discredit wave-equation formulations of cochlear mechanics (i.e., cochlear responses to excitation at a point along the basilar membrane) are readily reproduced and interpreted using a simple superposition of forward- and backward-traveling waves. Nobili and coworkers critique of wave-equation formulations of cochlear mechanics thus appears to be without compelling foundation. Although the traveling-wave and hydrodynamic formulations impose strikingly disparate conceptual and computational frameworks, the two approaches ultimately describe the same underlying physics.     

Otoacoustic Estimation of Cochlear Tuning: Validation in the Chinchilla

We analyze published auditory-nerve and otoacoustic measurements in chinchilla to test a network of hypothesized relationships between cochlear tuning, cochlear traveling-wave delay, and stimulus-frequency otoacoustic emissions (SFOAEs). We find that the physiological data generally corroborate the network of relationships, including predictions from filter theory and the coherent-reflection model of OAE generation, at locations throughout the cochlea. The results support the use of otoacoustic emissions as noninvasive probes of cochlear tuning. Developing this application, we find that tuning ratios—defined as the ratio of tuning sharpness to SFOAE phase-gradient delay in periods—have a nearly species-invariant form in cat, guinea pig, and chinchilla. Analysis of the tuning ratios identifies a species-dependent parameter that locates a transition between “apical-like” and “basal-like” behavior involving multiple aspects of cochlear physiology. Approximate invariance of the tuning ratio allows determination of cochlear tuning from SFOAE delays. We quantify the procedure and show that otoacoustic estimates of chinchilla cochlear tuning match direct measures obtained from the auditory nerve. By assuming that invariance of the tuning ratio extends to humans, we derive new otoacoustic estimates of human cochlear tuning that remain mutually consistent with independent behavioral measurements obtained using different rationales, methodologies, and analysis procedures. The results confirm that at any given characteristic frequency (CF) human cochlear tuning appears sharper than that in the other animals studied, but varies similarly with CF. We show, however, that the exceptionality of human tuning can be exaggerated by the ways in which species are conventionally compared, which take no account of evident differences between the base and apex of the cochlea. Finally, our estimates of human tuning suggest that the spatial spread of excitation of a pure tone along the human basilar membrane is comparable to that in other common laboratory animals.     

Changes in Pitch with a Cochlear Implant Over Time

In the normal auditory system, the perceived pitch of a tone is closely linked to the cochlear place of vibration. It has generally been assumed that high-rate electrical stimulation by a cochlear implant electrode also evokes a pitch sensation corresponding to the electrode’s cochlear place (“place” code) and stimulation rate (“temporal” code). However, other factors may affect electric pitch sensation, such as a substantial loss of nearby nerve fibers or even higher-level perceptual changes due to experience. The goals of this study were to measure electric pitch sensations in hybrid (short-electrode) cochlear implant patients and to examine which factors might contribute to the perceived pitch. To look at effects of experience, electric pitch sensations were compared with acoustic tone references presented to the non-implanted ear at various stages of implant use, ranging from hookup to 5 years. Here, we show that electric pitch perception often shifts in frequency, sometimes by as much as two octaves, during the first few years of implant use. Additional pitch measurements in more recently implanted patients at shorter time intervals up to 1 year of implant use suggest two likely contributions to these observed pitch shifts: intersession variability (up to one octave) and slow, systematic changes over time. We also found that the early pitch sensations for a constant electrode location can vary greatly across subjects and that these variations are strongly correlated with speech reception performance. Specifically, patients with an early low-pitch sensation tend to perform poorly with the implant compared to those with an early high-pitch sensation, which may be linked to less nerve survival in the basal end of the cochlea in the low-pitch patients. In contrast, late pitch sensations show no correlation with speech perception. These results together suggest that early pitch sensations may more closely reflect peripheral innervation patterns, while later pitch sensations may reflect higher-level, experience-dependent changes. These pitch shifts over time not only raise questions for strict place-based theories of pitch perception, but also imply that experience may have a greater influence on cochlear implant perception than previously thought.     

Age-Related Primary Cochlear Neuronal Degeneration in Human Temporal Bones

In cases of acquired sensorineural hearing loss, death of cochlear neurons is thought to arise largely as a result of sensory-cell loss. However, recent studies of acoustic overexposure report massive degeneration of the cochlear nerve despite complete hair cell survival (Kujawa and Liberman, J Neurosci 29:14077–14085, 2009). To assess the primary loss of spiral ganglion cells (SGCs) in human ears, neuronal counts were performed in 100 temporal bones from 100 individuals, aged newborn to 100 years, selected to include only cases with a normal population of inner and outer hair cells. Ganglion cell counts declined at a mean rate of 100 cells per year of life. There were no significant gender or inter-aural differences, and a slight increase in degeneration in the basal turn re upper turns was not statistically significant. The age-related decline in SGCs was significantly less than that in prior studies that included ears with hair cell loss (Otte et al., Laryngoscope 88:1231–1246, 1978), but significantly more than for analogous data on vestibular ganglion cells in cases without vestibular hair cell loss (Velazquez-Villasenor et al., Ann Otol Rhinol Laryngol Suppl 181:14–19, 2000). The age-related decline in SGC counts may contribute to the well-known decline in hearing-in-noise performance, and the data will help in interpretation of histopathological findings from temporal bones with known otologic disease.     

Analysis of the Cochlear Amplifier Fluid Pump Hypothesis

We use analysis of a realistic three-dimensional finite-element model of the tunnel of Corti (ToC) in the middle turn of the gerbil cochlea tuned to the characteristic frequency (CF) of 4 kHz to show that the anatomical structure of the organ of Corti (OC) is consistent with the hypothesis that the cochlear amplifier functions as a fluid pump. The experimental evidence for the fluid pump is that outer hair cell (OHC) contraction and expansion induce oscillatory flow in the ToC. We show that this oscillatory flow can produce a fluid wave traveling in the ToC and that the outer pillar cells (OPC) do not present a significant barrier to fluid flow into the ToC. The wavelength of the resulting fluid wave launched into the tunnel at the CF is 1.5 mm, which is somewhat longer than the wavelength estimated for the classical traveling wave. This fluid wave propagates at least one wavelength before being significantly attenuated. We also investigated the effect of OPC spacing on fluid flow into the ToC and found that, for physiologically relevant spacing between the OPCs, the impedance estimate is similar to that of the underlying basilar membrane. We conclude that the row of OPCs does not significantly impede fluid exchange between ToC and the space between the row of OPC and the first row of OHC–Dieter’s cells complex, and hence does not lead to excessive power loss. The BM displacement resulting from the fluid pumped into the ToC is significant for motion amplification. Our results support the hypothesis that there is an additional source of longitudinal coupling, provided by the ToC, as required in many non-classical models of the cochlear amplifier.     

Influence of a 6–8 kHz audiometric notch on transient evoked otoacoustic emissions

Thirty-eight patients with known unilateral cochlear hearing loss at 6 and/or 8 kHz were examined for transient evoked otoacoustic emisssions (TEOAEs). These findings were compared with those of the contralateral “normal hearing” ear. Statistically significant lower values of echo reproducibility and amplitude were recorded in hearing-impaired ears, together with a more narrow TEOAE spectrum. In addition to these findings, a globally reduced amplitude of the cochlear response was found that was unrelated to the frequency impaired in pure-tone audiometry (6, 8, or 6–8 kHz). Since patients’ audiometric thresholds at such frequencies could influence test results, findings could possibly be due to an altered echo travelling wave across the most basal part of the cochlea or to coexisting damage in the rest of Corti’s organ that were undetectable with standard audiometry. A significant overlap was found between the results from hearing-impaired ears and those from normally hearing ones. Although TEOAEs were not helpful in the present study in identifying patients with a unilateral hearing loss at 6 and/ or 8 kHz when compared to normal contralateral ears, they are still considered to play an important role in the follow-up of subjects at risk for hearing damage. Received: 22 December 1997 / Accepted: 14 May 1998     

Perceptual Adaptation to Spectrally Shifted Vowels: Training with Nonlexical Labels

Although normal-hearing (NH) and cochlear implant (CI) listeners are able to adapt to spectrally shifted speech to some degree, auditory training has been shown to provide more complete and/or accelerated adaptation. However, it is unclear whether listeners use auditory and visual feedback to improve discrimination of speech stimuli, or to learn the identity of speech stimuli. The present study investigated the effects of training with lexical and nonlexical labels on NH listeners’ perceptual adaptation to spectrally degraded and spectrally shifted vowels. An eight-channel sine wave vocoder was used to simulate CI speech processing. Two degrees of spectral shift (moderate and severe shift) were studied with three training paradigms, including training with lexical labels (i.e., “hayed,” “had,” “who’d,” etc.), training with nonlexical labels (i.e., randomly assigned letters “f,” “b,” “g,” etc.), and repeated testing with lexical labels (i.e., “test-only” paradigm without feedback). All training and testing was conducted over 5 consecutive days, with two to four training exercises per day. Results showed that with the test-only paradigm, lexically labeled vowel recognition significantly improved for moderately shifted vowels; however, there was no significant improvement for severely shifted vowels. Training with nonlexical labels significantly improved the recognition of nonlexically labeled vowels for both shift conditions; however, this improvement failed to generalize to lexically labeled vowel recognition with severely shifted vowels. Training with lexical labels significantly improved lexically labeled vowel recognition with severely shifted vowels. These results suggest that storage and retrieval of speech patterns in the central nervous system is somewhat robust to tonotopic distortion and spectral degradation. Although training with nonlexical labels may improve discrimination of spectrally distorted peripheral patterns, lexically meaningful feedback is needed to identify these peripheral patterns. The results also suggest that training with lexically meaningful feedback may be beneficial to CI users, especially patients with shallow electrode insertion depths.     

Interactions in the cochlea between air conduction and osseous and non-osseous bone conduction stimulation

Since air-conducted (AC) and clinical (mastoid) bone-conducted (BC) sounds interact in the cochlea (e.g. pitch, cancellation, masking, beats), it has been thought that both AC and BC stimulations lead to a mechanical wave in the cochlea. However, there are also “non-osseous” forms of BC, i.e. auditory sensation produced when the clinical bone vibrator is applied to “non-osseous” soft tissue sites. In the present study, such “non-osseous” sites were identified (e.g. eye, cheek, neck) and they interacted with AC and osseous BC (pitch matching, beats, masking), indicating that all of these forms of auditory stimulation converge in the cochlea, producing the same pattern of mechanical activity, leading to their interactions.     

Effects of Electrical Stimulation of Olivocochlear Fibers in Cochlear Potentials in the Chinchilla

The mammalian cochlea has two types of sensory cells; inner hair cells, which receive auditory-nerve afferent innervation, and outer hair cells, innervated by efferent axons of the medial olivocochlear (MOC) system. The role of the MOC system in hearing is still controversial. Recently, by recording cochlear potentials in behaving chinchillas, we suggested that one of the possible functions of the efferent system is to reduce cochlear sensitivity during attention to other sensory modalities (Delano et al. in J Neurosci 27:4146–4153, 2007). However, in spite of these compelling results, the physiological effects of electrical MOC activation on cochlear potentials have not been described in detail in chinchillas. The main objective of the present work was to describe these efferent effects in the chinchilla, comparing them with those in other species and in behavioral experiments. We activated the MOC efferent axons in chinchillas with sectioned middle-ear muscles by applying current pulses at the fourth-ventricle floor. Auditory-nerve compound action potentials (CAP) and cochlear microphonics (CM) were acquired in response to clicks and tones of several frequencies, using a round-window electrode. Electrical efferent stimulation produced CAP amplitude suppressions reaching up to 11 dB. They were higher for low to moderate sound levels. Additionally, CM amplitude increments were found, the largest (≤ 2.5 dB) for low intensity tones. CAP suppression was present at all stimulus frequencies, but was greatest for 2 kHz. CM increments were highest for low-frequency tones, and almost absent at high frequencies. We conclude that the effect obtained in chinchilla is similar to but smaller than that observed in cats, and that the effects seen in awake chinchillas, albeit different in magnitude, are consistent with the activation of efferent fibers.     

Frequency Map for the Human Cochlear Spiral Ganglion: Implications for Cochlear Implants

The goals of this study were to derive a frequency–position function for the human cochlear spiral ganglion (SG) to correlate represented frequency along the organ of Corti (OC) to location along the SG, to determine the range of individual variability, and to calculate an “average” frequency map (based on the trajectories of the dendrites of the SG cells). For both OC and SG frequency maps, a potentially important limitation is that accurate estimates of cochlear place frequency based upon the Greenwood function require knowledge of the total OC or SG length, which cannot be determined in most temporal bone and imaging studies. Therefore, an additional goal of this study was to evaluate a simple metric, basal coil diameter that might be utilized to estimate OC and SG length. Cadaver cochleae (n = 9) were fixed <24 h postmortem, stained with osmium tetroxide, microdissected, decalcified briefly, embedded in epoxy resin, and examined in surface preparations. In digital images, the OC and SG were measured, and the radial nerve fiber trajectories were traced to define a series of frequency-matched coordinates along the two structures. Images of the cochlear turns were reconstructed and measurements of basal turn diameter were made and correlated with OC and SG measurements. The data obtained provide a mathematical function for relating represented frequency along the OC to that of the SG. Results showed that whereas the distance along the OC that corresponds to a critical bandwidth is assumed to be constant throughout the cochlea, estimated critical band distance in the SG varies significantly along the spiral. Additional findings suggest that measurements of basal coil diameter in preoperative images may allow prediction of OC/SG length and estimation of the insertion depth required to reach specific angles of rotation and frequencies. Results also indicate that OC and SG percentage length expressed as a function of rotation angle from the round window is fairly constant across subjects. The implications of these findings for the design and surgical insertion of cochlear implants are discussed.     

3D-finite element model of the human cochlea including fluid-structure couplings.

The propagation of acoustic waves in the inner ear in vivo could not be quantified completely yet. This is in particular true in conjunction with the micromechanical structures of the organ of Corti, though these data are important for the explanation and discussion of clinical measurements like otoacoustic emissions and auditory brainstem responses. To access these problems a three-dimensional mechanical model of the cochlea including the fluid-structure couplings is developed and evaluated numerically by finite elements. Although the complex cochlear partition is covered by passive mechanical elements, the results fit early experiments (1928), which studied the wave propagation in the cochlea with fresh human cadavers [G. von Békésy: Experiments in Hearing. New York, McGraw-Hill, 1960]. Additionally it is now easy to calculate the mechanical input impedance of the cochlea. These results agree with recent experiments [S.N. Merchant et al.: Hear Res 1996;97:30-45].     

Zur neuen Diagnostik von Liquorfisteln

Der Beitrag “Beta-trace-Protein in der Diagnostik der Liquorfistel” von G. Bachmann et al. in der vorliegenden Ausgabe der “HNO” (Seite 496–500) zur neuen Diagnostik von Liquorfisteln ist beachtenswert. Spezifische Proteine, die im Liquor isoliert werden konnten, wurden mittels Rocket-Immunelektrophorese untersucht. Dabei zeigte sich, dass diese Diagnostik durch hohe Sensitivit?t und Spezifit?t andere Untersuchungsmethoden überragt.     

Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones

We present the first simultaneous sound pressure measurements in scala vestibuli and scala tympani of the cochlea in human cadaveric temporal bones. The technique we employ, which exploits microscale fiberoptic pressure sensors, enables the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. In our results, the sound pressure in scala vestibuli (P _SV) was much greater than scala tympani pressure (P _ST), except for very low and high frequencies where P _ST significantly affected the input to the cochlea. The differential pressure (P _SV − P _ST) is a superior measure of ossicular transduction of sound compared to P _SV alone: (P _SV−P _ST) was reduced by 30 to 50 dB when the ossicular chain was disarticulated, whereas P _SV was not reduced as much. The middle ear gain P _SV/P _EC and the differential pressure normalized to ear canal pressure (P _SV − P _ST)/P _EC were generally bandpass in frequency dependence. At frequencies above 1 kHz, the group delay in the middle ear gain is about 83 μs, over twice that of the gerbil. Concurrent measurements of stapes velocity produced estimates of cochlear input impedance, the differential impedance across the partition, and round window impedance. The differential impedance was generally resistive, while the round window impedance was consistent with compliance in conjunction with distributed inertia and damping. Our technique of measuring differential pressure can be used to study inner ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round window stimulation and bone conduction)—situations that cannot be completely quantified by measurements of stapes velocity or scala vestibuli pressure by themselves.     

Encoding Intensity in Ventral Cochlear Nucleus Following Acoustic Trauma: Implications for Loudness Recruitment

Loudness recruitment, an abnormally rapid growth of perceived loudness with sound level, is a common symptom of sensorineural hearing loss. Following acoustic trauma, auditory-nerve rate responses are reduced, and rate grows more slowly with sound level, which seems inconsistent with recruitment (Heinz et al., J. Assoc. Res. Otolaryngol. 6:91–105, 2005). However, rate-level functions (RLFs) in the central nervous system may increase in either slope or saturation value following trauma (e.g., Salvi et al., Hear. Res. 147:261–274, 2000), suggesting that recruitment may arise from central changes. In this paper, we studied RLFs of neurons in ventral cochlear nucleus (VCN) of the cat after acoustic trauma. Trauma did not change the general properties of VCN neurons, and the usual VCN functional classifications remained valid (chopper, primary-like, onset, etc.). After trauma, non-primary-like neurons, most noticeably choppers, exhibited elevated maximum discharge rates and steeper RLFs for frequencies at and near best frequency (BF). Primary-like neurons showed the opposite changes. To relate the neurons’ responses to recruitment, rate-balance functions were computed; these show the sound level required to give equal rates in a normal and a traumatized ear and are analogous to loudness balance functions that show the sound levels giving equal perceptual loudness in the two ears of a monaurally hearing-impaired person. The rate-balance functions showed recruitment-like steepening of their slopes in non-primary-like neurons in all conditions. However, primary-like neurons showed recruitment-like behavior only when rates were summated across neurons of all BFs. These results suggest that the non-primary-like, especially chopper, neurons may be the most peripheral site of the physiological changes in the brain that underlie recruitment.     

A decade of laryngeal dysplasia in Paisley, Scotland

Laryngeal dysplasia is a known premalignant condition. A recent consensus statement by otorhinolaryngologists and pathologists on the diagnosis and management of laryngeal dysplasia Mehanna et al. (Clin Otol 35:170–176, 2010) identified a need for retrospective data on epidemiological aspects of laryngeal dysplasia as well as responses to treatment. A retrospective search was made on the hospital pathology database for cases of laryngeal dysplasia. Searches were made under “Larynx”, “Dysplasia”, “Carcinoma in situ” and “Vocal Cord”. The search dates were between 1998 to the present day. The returned records were checked with the pathology reports and the case notes of these patients requested for analysis. A proforma was completed for each patient with laryngeal dysplasia. These patients were then anonymised, entered into a spreadsheet and analysed. The initial search returned 937 patients. Of these patients, 505 (54%) had benign laryngeal pathology, 131 (14%) had laryngeal dysplasia and 301 (32%) had invasive cancer on biopsy. Patients who developed malignancy within 3 months of being diagnosed with laryngeal dysplasia were excluded. This left 110 patients for analysis. Of the dysplastic patients, 40 (36%) had mild dysplasia, 31 (28%) had moderate dysplasia and 39 (35%) had severe dysplasia/carcinoma in situ; 70% were male. The median age was 63 (min 21, max 90, ave 62.5); 74 (67%) were smokers or ex-smokers. Progression of dysplasia was seen in 7 (6%) patients. Malignant transformation was seen in 18 (16%) patients. The average time for malignant change was 43 months (min 4 months, max 192 months and median 15.5 months; 73 (66%) patients were treated by microlaryngeal resection, 2 (2%) were treated by vocal cord stripping, 28 (25%) were treated by endolaser therapy, and 1 (1%) patient was treated by using the microdebrider skimming blade and 6 (5%) were treated by radiotherapy. Cure of dysplasia or downgrading of severity in these treatment subgroups was 62 (85%), 2 (100%), 24 (86%), 1 (100%) and 4 (66%), respectively. Our study reiterates that laryngeal dysplasia carries a significant risk of developing malignancy. Management of this condition varies widely. Endolaser resection is becoming more frequently employed in the UK. Our study is biased heavily towards cold steel dissection. Although there is increasing practice in the UK to promote early discharge, we feel it may be safer to keep patients under surveillance for longer periods. Despite this, all patients who returned after discharge or failing to attend with invasive cancer did so with new symptoms.     

Surgery did not improve the subjective neuropsychological symptoms of patients with incidentally detected mild primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is known to cause diverse subjective symptoms, in addition to those related to osteitis fibrosa cystica and kidney stones. The treatment of the disease ameliorates the subjective symptoms and improves the patients’ quality of life. In this prospective study, patients undergoing surgery for incidentally detected, mild, asymptomatic PHPT were assessed to determine whether subjective neuropsychological symptoms are improved even in patients with “asymptomatic” PHPT. From October 1995 to March 2004, 25 patients who had one or more neuropsychological symptoms preoperatively and were followed up 1 year after parathyroidectomy were enrolled. The subjective symptoms were identified using questionnaires distributed to patients; eight questions were used to determine the presence or absence of psychoneurological symptoms. Compared to their preoperative status, patients responded that their general health perceptions 1 year after surgery were improved (13 cases, 52%), unchanged (11 cases, 44%), or aggravated (1 case, 4%). There were no statistically significant differences in the patients’ responses before and after surgery with respect to individual neuropsychological symptoms, such as “tiring easily, “forgetfulness,” “decreased concentration,” “depression,” “irritability,” “uneasiness,” and “sleeplessness.” Therefore, subjective neuropsychological symptoms did not improve in otherwise asymptomatic PHPT patients following parathyroidectomy. However, patients’ questionnaire responses may not reflect their actual status as accurately as laboratory examination results. Overall, 52% of patients were subjectively satisfied with surgery; this may result from patients’ expectations of treatment.