Axillary artery injury combined with delayed brachial plexus palsy due to compressive hematoma in a young patient: a case report

Aim

To prove the possibility of axillary nerve conduction changes following shoulder subluxation due to hemiplegia, in order to investigate the usefulness of screening nerve conduction studies in patients with hemiplegia for finding peripheral neuropathy.

Methods

Forty-four shoulders of twenty-two patients with a first-time stroke having flaccid hemiplegia were tested, 43 ± 12 days after stroke onset. Wasting and weakness of the deltoid were present in the involved side. Motor nerve conduction latency and compound muscle action potential (CMAP) amplitude were measured along the axillary nerve, comparing the paralyzed to the sound shoulder. The stimulation was done at the Erb's point whilst the recording needle electrode was inserted into the deltoid muscle 4 cm directly beneath the lateral border of the acromion. Wilcoxon signed rank test was used to compare the motor conduction between the sound and the paralytic shoulder. Mann-Whitney test was used to compare between plegic and sound shoulder in each side.

Results

Mean motor nerve conduction latency time to the deltoid muscle was 8.49, SD 4.36 ms in the paralyzed shoulder and 5.17, SD 1.35 ms in the sound shoulder (p < 0.001). Mean compound muscle action potential (CMAP) amplitude was 2.83, SD 2.50 mV in the paralyzed shoulder and was 7.44, SD 5.47 mV in the sound shoulder (p < 0.001). Patients with right paralyzed shoulder compared to patients with right sound shoulder (p < 0.001, 1-sided for latency; p = 0.003, 1-sided for amplitude), and patients with left paralyzed shoulder compared to patients with left sound shoulder (p = 0.011, 1-sided for latency, p = 0.001, 1-sided for amplitude), support the same outcomes. The electro-physiological changes in the axillary nerve may appear during the first six weeks after stroke breakout.

Conclusion

Continuous traction of the axillary nerve, as in hypotonic shoulder, may affect the electro-physiological properties of the nerve. It most probably results from subluxation of the head of the humerus, causing demyelinization and even axonopathy. Slowing of the conduction velocities of the axillary nerve in the paralyzed shoulders may be related also to the lowering of the skin temperature and muscular atrophy in the same limb. The usefulness of routine screening nerve conduction studies in the shoulder of hemiplegic patients seems to be advocated.     

Whip use by jockeys in a sample of Australian Thoroughbred races--an observational study

The use of whips by jockeys is an issue. The current study viewed opportunistic high-speed footage of 15 race finishes frame-by-frame to examine the outcomes of arm and wrist actions (n = 350) on 40 horses viewed from the left of the field. Any actions fully or partially obscured by infrastructure or other horses were removed from the database, leaving a total of 104 non-contact sweeps and 134 strikes. For all instances of arm actions that resulted in fully visible whip strikes behind the saddle (n = 109), the outcomes noted were area struck, percentage of unpadded section making contact, whether the seam made contact and whether a visible indentation was evident on impact. We also recorded use of clockwise or counter-clockwise arm action from each jockey''s whip, whether the whip was held like a tennis racquet or a ski pole, whether the hind leg on the side of the impact was in stance or swing phase and whether the jockey''s arm was seen traveling above shoulder height. The goal of the study was to characterize the area struck and the visual impact of whip use at the level of the horse. We measured the ways in which both padded and unpadded sections of the whip made impact. There was evidence of at least 28 examples, in 9 horses, of breaches of the whip rules (one seam contact, 13 contacts with the head, and 14 arm actions that rose above the height of the shoulder). The whip caused a visible indentation on 83% of impacts. The unpadded section of the whip made contact on 64% of impacts. The results call into question the ability of Stewards to effectively police the rules concerning whip use and, more importantly, challenge the notion that padding the distal section of whips completely safeguards horses from any possible whip-related pain.     

Shoulder joint kinetics and dynamics during underwater forward arm elevation

Aquatic exercises are widely implemented into rehabilitation programs. However, both evaluating their mechanical demands on the musculoskeletal system and designing protocols to provide progressive loading are difficult tasks. This study reports for the first time shoulder joint kinetics and dynamics during underwater forward arm elevation performed at speeds ranging from 22.5 to 90°/s. Net joint moments projected onto anatomical axes of rotation, joint power, and joint work were calculated in 18 participants through a novel approach coupling numerical fluid flow simulations and inverse dynamics. Joint dynamics was revealed from the 3D angle between the joint moment and angular velocity vectors, identifying three main functions—propulsion, stabilization, and resistance. Speeds <30°/s necessitated little to no power at all, whereas peaks about 0.20 W⋅kg⁻¹ were seen at 90°/s. As speed increased, peak moments were up to 61 × higher at 90 than at 22.5°/s, (1.82 ± 0.12%BW⋅AL vs 0.03 ± 0.01%BW⋅AL, P < 0.038). This was done at the expense of a substantial decrease in the joint moment contribution to joint stability though, which goes against the intuition that greater stabilization is required to protect the shoulder from increasing loads. Slow arm elevations (<30°/s) are advantageous for joint mobility gain at low mechanical solicitation, whereas the intensity at 90°/s is high enough to stimulate muscular endurance improvements. Simple predictive equations of shoulder mechanical loading are provided. They allow for easy design of progressive protocols, either for the postoperative shoulder or the conditioning of athlete targeting very specific intensity regions.     

Harmonic Hopping,and Both Punctuated and Gradual Evolution of Acoustic Characters in Selasphorus Hummingbird Tail-Feathers

Models of character evolution often assume a single mode of evolutionary change, such as continuous, or discrete. Here I provide an example in which a character exhibits both types of change. Hummingbirds in the genus Selasphorus produce sound with fluttering tail-feathers during courtship. The ancestral character state within Selasphorus is production of sound with an inner tail-feather, R2, in which the sound usually evolves gradually. Calliope and Allen''s Hummingbirds have evolved autapomorphic acoustic mechanisms that involve feather-feather interactions. I develop a source-filter model of these interactions. The ‘source’ comprises feather(s) that are both necessary and sufficient for sound production, and are aerodynamically coupled to neighboring feathers, which act as filters. Filters are unnecessary or insufficient for sound production, but may evolve to become sources. Allen''s Hummingbird has evolved to produce sound with two sources, one with feather R3, another frequency-modulated sound with R4, and their interaction frequencies. Allen''s R2 retains the ancestral character state, a ∼1 kHz “ghost” fundamental frequency masked by R3, which is revealed when R3 is experimentally removed. In the ancestor to Allen''s Hummingbird, the dominant frequency has ‘hopped’ to the second harmonic without passing through intermediate frequencies. This demonstrates that although the fundamental frequency of a communication sound may usually evolve gradually, occasional jumps from one character state to another can occur in a discrete fashion. Accordingly, mapping acoustic characters on a phylogeny may produce misleading results if the physical mechanism of production is not known.     

Comparisons of therapeutic effects of levodopa,levodopa and selegiline,and bromocriptine in patients with early,mild Parkinson's disease: three year interim report. Parkinson's Disease Research Group in the United Kingdom.

OBJECTIVE--To determine the optimum treatment for early Parkinson''s disease. DESIGN--An open, long term, prospective randomised trial conducted by the Parkinson''s Disease Research Group of the United Kingdom. SETTING--93 hospitals throughout the United Kingdom. SUBJECTS--782 patients with early Parkinson''s disease who were not receiving dopaminergic treatment. INTERVENTIONS--Patients allocated to treatment with levodopa/dopa decarboxylase inhibitor alone (arm 1), levodopa/decarboxylase inhibitor/selegiline in combination (arm 2), or bromocriptine (arm 3). MAIN OUTCOME MEASURES--Disability assessment as judged by improvement on Hoehn and Yahr, modified Webster, and North Western University disability scales. Adverse event profile and mortality ratios. RESULTS--Interim results indicate that all three treatment regimens led to improvement in baseline disabilities after 12 months'' treatment and that deterioration in control was apparent by three years. No significant differences were found between the results of treatment in arm 1 and arm 2, but both were significantly more effective than bromocriptine (arm 3) and had fewer early adverse reactions. The adjusted difference (95% confidence interval) in Webster rating for arm 3 v 1 was 0.93 points (0.27 to 1.50; p = 0.0058) and for arm 3 v 2 was 1.25 points (0.61 to 1.89; p = 0.0002). The incidence of dyskinesias and motor oscillations, however, was significantly lower in arm 3 (2% and 5%, respectively) than in arm 1 (27% and 33%, respectively) and arm 2 (34% and 35%, respectively). CONCLUSIONS--As there were no marked differences in functional improvement between the three groups the choice of treatment in the early stages of Parkinson''s disease may not be critical.     

Comparison of therapeutic effects and mortality data of levodopa and levodopa combined with selegiline in patients with early,mild Parkinson's disease. Parkinson's Disease Research Group of the United Kingdom.

OBJECTIVE: To compare effectiveness of levodopa and levodopa combined with selegiline in treating early, mild Parkinson''s disease. DESIGN: Open, long term, prospective randomised trial. SETTING: 93 hospitals throughout United Kingdom. SUBJECTS: 520 patients with early Parkinson''s disease who were not receiving dopaminergic treatment. INTERVENTIONS: Treatment with levodopa and dopa decarboxylase inhibitor (arm 1) or levodopa and decarboxylase inhibitor in combination with selegiline (arm 2). MAIN OUTCOME MEASURES: Assessments of serial disability, frequency and severity of adverse events, and deaths from all causes. RESULTS: After average of 5-6 years'' follow up, mortality ratio in arm 2 compared with arm 1 was 1.57 (95% confidence interval 1.09 to 2.30), and difference in survival between the two arms was significant (log rank test, P = 0.015). Hazard ratio adjusted for age and sex was 1.49 (1.02 to 2.16), and after adjustment for other baseline factors it increased to 1.57 (1.07 to 2.31). Patients in arm 1 had slightly worse disability scores than those in arm 2, but differences were not significant. Functionally disabling peak dose dyskinesias and on/off fluctuations were more frequent in arm 2 than arm 1. During the trial the dose of levodopa required to produce optimum motor control steadily increased in arm 1 (median daily dose 375 mg at 1 year and 625 mg at 4 years), but median dose in arm 2 did not change (375 mg). CONCLUSIONS: Levodopa in combination with selegiline seemed to confer no clinical benefit over levodopa alone in treating early, mild Parkinson''s disease. Moreover mortality was significantly higher with combination treatment, casting doubts on its chronic use in Parkinson''s disease.     

Posture-movement changes following repetitive motion-induced shoulder muscle fatigue

Repetitive motion-induced fatigue not only alters local motion characteristics but also provokes global reorganization of movement. However, the three-dimensional (3D) characteristics of these reorganization patterns have never been documented in detail. The goal of this study was to assess the effects of repetitive reaching-induced arm fatigue on the whole-body, 3D biomechanical task characteristics. Healthy subjects (N = 14) stood and performed a continuous reaching task (RRT) between two targets placed at shoulder height to fatigue. Whole-body kinematic (Vicon^©), kinetic (AMTI^© force platforms) and electromyographic (EMG, Noraxon^©) characteristics were recorded. Maximal voluntary isometric efforts (MVIE) of the shoulder and elbow were measured pre- and post-RRT. Post-RRT shoulder elevation MVIE was reduced by 4.9 ± 8.3% and trapezius EMG amplitude recorded during the RRT increased by 46.9 ± 49.9% from the first to last minute of the RRT, indicating that arm fatigue was effectively induced. During fatigued reaching, subjects elevated their shoulder (11.7 ± 10.5 mm) and decreased their average shoulder abduction angle by 8.3 ± 4.4°. These changes were accompanied by a lateral shift of the body’s center of mass towards the non-reaching arm. These findings suggest a compensatory strategy to decrease the load on the fatigued shoulder musculature.     

懒猴肩关节的多变量分析

在懒猴与其它灵长类肩关节局部解剖的基础上,对肩关节有关指数的多变量分析结果表明,与骨骼相比,肩关节肌的种间差别明显较大。肩胛盂宽指数、肩胛骨指数和锁肱指数对种的区分有重要意义。懒猴具有类似于叶猴三角肌、大圆肌和喙肱中肌较远的止点及发达的背阔肌和斜方肌颅侧部,增强了肩关节的运动,表现出适应树栖四足运动的特征。而懒猴粗壮的肱骨、较长的锁骨和较长的肱骨,是攀爬型和四足倒挂运动的适应结果。     

A Preliminary Investigation Regarding the Effect of Tennis Grunting: Does White Noise During a Tennis Shot Have a Negative Impact on Shot Perception?

Background

There is a growing chorus of critics who complain that many of the top-ranked professional tennis players who grunt when they hit the ball gain an unfair advantage because the sound of the grunt interferes with their opponent''s game. However, there is no scientific evidence to support this claim.

Methodology/Principal Findings

We explored this potential detrimental effect of grunting by presenting videos of a tennis player hitting a ball to either side of a tennis court; the shot either did, or did not, contain a brief sound that occurred at the same time as contact. The participants'' task was to respond as quickly as possible, indicating whether the ball was being hit to the left- or right-side of the court. The results were unequivocal: The presence of an extraneous sound interfered with a participants'' performance, making their responses both slower and less accurate.

Conclusions/Significance

Our data suggest that a grunting player has a competitive edge on the professional tennis tour. The mechanism that underlies this effect is a topic for future investigation. Viable alternatives are discussed. For example, the possibility that the interfering auditory stimulus masks the sound of the ball being struck by the racket or it distracts an opponent''s attention away from the sound of the ball.     

A triceps musculocutaneous flap for chest-wall defects

A posterior upper arm flap based on the profunda brachii vessels has been described to cover soft-tissue defects in the upper anterolateral chest. In our series, the posterior upper arm skin is elevated with the long head of the triceps muscle to cover seven chest-wall defects resulting from indolent postradiation open wounds following partial TRAM flap failure (n = 2), soft-tissue deficiencies following partial TRAM flap loss (n = 3), and primarily as an ancillary flap in TRAM flap breast reconstruction (n = 2). This flap also may be used to supply well-vascularized tissue in the regions of the shoulder, axilla, and posterolateral back. A prerequisite for this operation is redundant tissue of the upper arm often present in middle-aged women and in patients with lymphedema following mastectomy. In our series of seven patients, all donor sites were closed primarily, and there was no subjective functional deficit following transfer of the long head of the triceps muscle.     

Vaccination scar with soft-tissue atrophy restored by local insulin treatment.

A woman who had a deep scar on her left arm as a result of an influenza vaccination was treated with insulin. Monocomponent porcine insulin was injected into each quadrant of the pit. After 82 days'' treatment her arm appeared normal and has remained so over seven months. Using insulin''s ability to promote fat and protein synthesis is a simple and effective way of treating atrophied scars.     

A new method for motion capture of the scapula using an optoelectronic tracking device: a feasibility study

Optoelectronic tracking systems are rarely used in 3D studies examining shoulder movements including the scapula. Among the reasons is the important slippage of skin markers with respect to scapula. Methods using electromagnetic tracking devices are validated and frequently applied. Thus, the aim of this study was to develop a new method for in vivo optoelectronic scapular capture dealing with the accepted accuracy issues of validated methods.

Eleven arm positions in three anatomical planes were examined using five subjects in static mode. The method was based on local optimisation, and recalculation procedures were made using a set of five scapular surface markers.

The scapular rotations derived from the recalculation-based method yielded RMS errors comparable with the frequently used electromagnetic scapular methods (RMS up to 12.6° for 150° arm elevation). The results indicate that the present method can be used under careful considerations for 3D kinematical studies examining different shoulder movements.     

Altered neural and behavioral dynamics in Huntington's disease: an entropy conservation approach

Background

Huntington''s disease (HD) is an inherited condition that results in neurodegeneration of the striatum, the forebrain structure that processes cortical information for behavioral output. In the R6/2 transgenic mouse model of HD, striatal neurons exhibit aberrant firing patterns that are coupled with reduced flexibility in the motor system. The aim of this study was to test the patterns of unpredictability in brain and behavior in wild-type (WT) and R6/2 mice.

Methodology/Principal Findings

Striatal local field potentials (LFP) were recorded from 18 WT and 17 R6/2 mice (aged 8–11 weeks) while the mice were exploring a plus-shaped maze. We targeted LFP activity for up to 2 s before and 2 s after each choice-point entry. Approximate Entropy (ApEn) was calculated for LFPs and Shannon Entropy was used to measure the probability of arm choice, as well as the likelihood of making consecutive 90-degree turns in the maze. We found that although the total number of choice-point crossings and entropy of arm-choice probability was similar in both groups, R6/2 mice had more predictable behavioral responses (i.e., were less likely to make 90-degree turns and perform them in alternation with running straight down the same arm), while exhibiting more unpredictable striatal activity, as indicated by higher ApEn values. In both WT and R6/2 mice, however, behavioral unpredictability was negatively correlated with LFP ApEn.

Conclusions/Significance

HD results in a perseverative exploration of the environment, occurring in concert with more unpredictable brain activity. Our results support the entropy conservation hypothesis in which unpredictable behavioral patterns are coupled with more predictable brain activation patterns, suggesting that this may be a fundamental process unaffected by HD.     

昆虫弦音器及其声音感受分子机制

弦音器是昆虫类特有的一种机械感受器,亦称弦音感受器或剑梢感受器。它主要具有感知外界声压和体内肌肉运动的听觉功能,研究弦音器的机能结构对揭秘昆虫听觉的神经机制有重要的科学意义。本文从弦音器多样性和进化入手,重点综述了弦音器的微细结构、基因功能定位、声音感受分子机制及其声压增幅分子生物物理学原理,为昆虫听觉仿生学的研究提供了理论依据。     

THE HIGH SCHOOL FOOTBALL TEAM PHYSICIAN

Mutual confidence is necessary between the football coach and the team physician. The physician''s decision in the matter of a boy''s condition must always be final. The coach should also consider the physician''s advice in shaping his psychological appeals to the players in before-game and between-halves talks. The physician should be on his way to a man injured on the field as soon as the play is ended. It is up to him and not the trainer or coach to make the diagnosis. The physician must have the ability to make an immediate evaluation of the extent of injury and use appropriate measures to get the player off the field. To see a semi-conscious man with dangling head being half dragged off the field is far worse from the patient''s standpoint and from the spectator''s standpoint than removal by stretcher.     

The range of passive arm circumduction in primates: Do hominoids really have more mobile shoulders?

Hominoids and lorines are assumed to possess greater shoulder mobility than other primates. This assumption is based on morphological characteristics of the shoulder, rather than on empirical data. However, recent studies have shown that the glenohumeral joint of hominoids is not more mobile than that of other primates (Chan LK. 2007. Glenohumeral mobility in primates. Folia Primatol (Basel) 78(1):1–18), and the thoracic shape of hominoids does not necessarily promote shoulder mobility (Chan LK. 2007. Scapular position in primates. Folia Primatol (Basel) 78(1):19–35). Moreover, lorines differ significantly from hominoids in both these features, thus challenging the assumption that both hominoids and lorines have greater shoulder mobility. The present study aims to test this assumption by collecting empirical data on shoulder mobility in 17 primate species. Passive arm circumduction (a combination of glenohumeral and pectoral girdle movement) was performed on sedated subjects (except humans), and the range measured on the video images of the circumduction. The motion differed among primate species mostly in the craniodorsal directions, the directions most relevant to the animal's ability to brachiate and slow climb. Hylobatids possessed the highest craniodorsal mobility among all primate species studied. However, nonhylobatid hominoids did not have greater craniodorsal mobility than arboreal quadrupedal monkeys, and lorines did not have greater craniodorsal mobility than arboreal quadrupedal prosimians. Nonhylobatid hominoids and lorines had similar craniodorsal mobility, but this was due to a longer clavicle, more dorsal scapula, and lower glenohumeral mobility in the former, and a shorter clavicle, less dorsal scapula, and greater glenohumeral mobility in the latter. This study provides evidence for the reexamination of the brachiation, slow climbing, and vertical climbing hypotheses. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.     

Early embryonic development of the mayfly Ephemera japonica McLachlan (Insecta: Ephemeroptera,Ephemeridae)

In the newly laid egg of the mayfly Ephemera japonica, an egg nucleus (oocyte nucleus) at metaphase of the first maturation division is in the polar plasm at the mid-ventral side of the egg, and a male pronucleus lies in the periplasm beneath a micropyle situated just opposite the polar plasm or at the mid-dorsal side of egg. The maturation divisions are typical. An extensive and circuitous migration of the male pronucleus is involved in the fertilization process: it first moves anteriad in the periplasm from beneath the micropyle to the anterior pole of the egg and then turns posteriad in the yolk along the egg's long axis to the site of syngamy, near the center of the egg. Cleavage is superficial. The successive eight cleavages, of which the first five are synchronized, result in the formation of the blastoderm, and about ten primary yolk cells remain behind in the yolk. Even in the newly formed blastoderm, the thick embryonic posterior half and the thin extraembryonic anterior half areas are distinguished: the former cells are concentrated at the posterior pole of the egg to form the germ disc, and the latter cells become more flattened, forming serosa. Time-lapse VTR observations reveal a yolk stream that is in accord with the migration of the male pronucleus in time and direction. The yolk stream is also generated in activated unfertilized eggs, and it is probable that the migration of the male pronucleus in association with the fertilization may be directed by the yolk stream. J. Morphol. 238:327–335, 1998. © 1998 Wiley-Liss, Inc.     

Scapular kinematics during unloaded and maximal loaded isokinetic concentric and eccentric shoulder flexion and extension movements

Characterization of scapular kinematics under demanding load conditions might aid to distinguish between physiological and clinically relevant alterations. Previous investigations focused only on submaximal external load situations. How scapular movement changes with maximal load remains unclear. Therefore, the present study aimed to evaluate 3D scapular kinematics during unloaded and maximal loaded shoulder flexion and extension. Twelve asymptomatic individuals performed shoulder flexion and extension movements under unloaded and maximal concentric and eccentric loaded isokinetic conditions. 3D scapular kinematics assessed with a motion capture system was analyzed for 20° intervals of humeral positions from 20° to 120° flexion. Repeated measures ANOVAs were used to evaluate kinematic differences between load conditions for scapular position angles, scapulohumeral rhythm and scapular motion extent. Increased scapular upward rotation was seen during shoulder flexion and extension as well as decreased posterior tilt and external rotation during eccentric and concentric arm descents of maximal loaded compared to unloaded conditions. Load effects were further seen for the scapulohumeral rhythm with greater scapular involvement at lower humeral positions and increased scapular motion extent under maximal loaded shoulder movements. With maximal load applied to the arm physiological scapular movement pattern are induced that may imply both impingement sparing and causing mechanisms.     

The tettigoniid (Orthoptera : Tettigoniidae) ear: Multiple functions and structural diversity

The ears of bushcrickets (Orthoptera : Tettigoniidae) consist of a pair of membranes situated beneath the knee of the foretibia. These membranes, or tympana, are backed by a tracheal system dedicated to sound reception. In most species, a trachea opens through a hole, the auditory spiracle, in the pleuron of the prothorax adjacent to the ventilatory spiracle. Experimental evidence clearly shows that in those species possessing such an opening, sound entering through this route is amplified by the shape of the trachea, or at least is modified through resonances created by its tracheal cavities or tubes. In some species the external surface of the tympanic membrane is surrounded by cuticular folds, which may be formed into small resonating cavities or sound guiding pinnae. In other species the tympana are naked. Sound interacts with the external surface of the tympana, either through these cuticular cavities or directly at the surface of the membrane. As with auditory tracheae, the shape of these cavities may modify sound through resonances. This review examines the role of both external and internal sound-guides in sound reception. It discusses how different species may utilize different sound receiving systems and suggests how, in some cases, both external and internal routes may respond to different frequency bands. The maximum sensitivity of the ear invariably coincides with the male's call carrier frequency. Two Australian species of tettigoniid where the ear is clearly not tuned to the male's call are described. The biology of one undescribed species belonging to the subfamily, Zaprochilinae, where not only is the ear untuned, but there is marked sexual dimorphism in ear structure, is elaborated on. The review concludes with an examination of the routes selection may have taken to arrive at the extreme morphologies present in the Tettigoniidae.     

A novel hearing specialization in the New Zealand bigeye,Pempheris adspersa

The New Zealand bigeye, Pempheris adspersa, is a nocturnal planktivore and has recently been found to be an active sound producer. The rostral end of the swim bladder lies adjacent to Baudelot''s ligament which spans between the bulla and the cleithrum bone of the pectoral girdle. The aim of this study was to use the auditory evoked potential technique to physiologically test the possibility that this structure provides an enhanced sensitivity to sound pressure in the bigeye. At 100 Hz, bigeye had hearing sensitivity similar to that of goldfish (species with a mechanical connection between the swim bladder and the inner ear mediated by the Weberian ossicles) and were much more sensitive than other teleosts without ancillary hearing structures. Severing Baudelot''s ligament bilaterally resulted in a marked decrease in hearing sensitivity, as did swim bladder puncture or lateral line blockage. These results show that bigeye have an enhanced sensitivity to sound pressure and provide experimental evidence that the functional basis of this sensitivity represents a novel hearing specialization in fish involving the swim bladder, Baudelot''s ligament and the lateral line.