Sizing ocean giants: patterns of intraspecific size variation in marine megafauna.

What are the greatest sizes that the largest marine megafauna obtain? This is a simple question with a difficult and complex answer. Many of the largest-sized species occur in the world's oceans. For many of these, rarity, remoteness, and quite simply the logistics of measuring these giants has made obtaining accurate size measurements difficult. Inaccurate reports of maximum sizes run rampant through the scientific literature and popular media. Moreover, how intraspecific variation in the body sizes of these animals relates to sex, population structure, the environment, and interactions with humans remains underappreciated. Here, we review and analyze body size for 25 ocean giants ranging across the animal kingdom. For each taxon we document body size for the largest known marine species of several clades. We also analyze intraspecific variation and identify the largest known individuals for each species. Where data allows, we analyze spatial and temporal intraspecific size variation. We also provide allometric scaling equations between different size measurements as resources to other researchers. In some cases, the lack of data prevents us from fully examining these topics and instead we specifically highlight these deficiencies and the barriers that exist for data collection. Overall, we found considerable variability in intraspecific size distributions from strongly left- to strongly right-skewed. We provide several allometric equations that allow for estimation of total lengths and weights from more easily obtained measurements. In several cases, we also quantify considerable geographic variation and decreases in size likely attributed to humans.

Epidural steroid injections in the treatment of lumbar spinal stenosis efficacy and predictability of successful response.

OBJECTIVE: The purpose of this study was to determine response to interlaminar epidural steroid injections in the treatment of lumbar spinal stenosis as measured using self-reported activity level and measured walking ability. The results were correlated through demographic data, magnetic resonance imaging (MRI) characteristics, and electrodiagnostic (EDX) results. DESIGN: Subjects with a history of painful ambulation and lumbar spinal stenosis confirmed by MRI (N = 17) underwent a detailed history, physical examination, EDX, completed the Swiss Spinal Stenosis Questionnaire (SSSQ), and performed a 6-Minute Walk Test (SMWT). All subjects received between one and three epidural steroid injections, depending on clinical response. The SSSQ and the SMWT were repeated approximately 6 wks after completion of the last injection. EDX was performed using previously published techniques. MRIs were reviewed and classified according to type, severity, and canal diameter. RESULTS: The subjects' initial performance on the SMWT was significantly worse than predicted normative data, accounting for age, sex, and measurements of height and weight. After completion of the treatment protocol, there was a significant improvement as measured by changes in SMWT (ΔSMWT; P = 0. 023) and SSSQ (ΔSMWT; P = 0.0003). ΔSMWT and ΔSSSQ only weakly correlated (r = 0.57). Body mass index, MRI, and EDX criteria were not predictive of ΔSMWT or ΔSSSQ. Younger subjects trended toward greater improvement than older subjects (ΔSMWT, -4.7 m/yr, P = 0.07, SSSQΔ P = 0.08). When adjusting for body mass index and sex, there was a significantly less improvement in walking distance with increasing age (ΔSMWT, -7.4 m/yr, P = 0.007). When adjusting for age and body mass index, women enjoyed a more robust treatment effect than did men (ΔSMWT, +106.9 m, P = 0.03). CONCLUSIONS: Epidural steroid injections is an effective treatment for improving ambulation and functional limitations caused by lumbar spinal stenosis. Relative youth and female sex are associated with a more favorable response. Body mass index, EDX abnormal findings, and MRI severity are not predictive.

Thenar motor syndrome: median mononeuropathy of the hand.

OBJECTIVE: To evaluate a population with presumed carpal tunnel syndrome (CTS) for isolated involvement of the median motor nerve distal latency at or near the thenar eminence. DESIGN: This prospective study performed in various outpatient venues randomly selected 500 railroad workers with hand symptoms and presumed CTS entering into litigation. Electrodiagnostic studies were performed by using common techniques and distances. The dominant hand of each subject was evaluated. A prolonged median minus ulnar nerve distal latency differential (MUD) was the standard for determining CTS. Subjects with an isolated delay of motor MUD, with a normal sensory and midpalmar MUD, were classified as having thenar motor syndrome (TMS). RESULTS: After eliminating all subjects who did not meet the criteria of the electrodiagnostic studies, there remained a cohort of 126 subjects. There were 38 who met the criteria for TMS, and all others were classified as true CTS. Both groups were overweight, and the body mass index of the true CTS group was significantly higher (P < 0.006). CONCLUSIONS: TMS is a distinct electrodiagnostic entity. As an artifact of the study design (the exclusion of subjects with prior surgery), the relative frequency of TMS was increased. Aside from body mass index, no anthropometric or demographic difference between TMS and true CTS was demonstrated. Although no occupation source was identified, a possible pathogenesis includes local trauma superimposed on a common anatomic variant.

Carpal tunnel syndrome in railroad workers.

OBJECTIVE: To determine, within a specific industry, if carpal tunnel syndrome (CTS) is associated with job classification or other personal risk factors. To determine if surgical intervention for the treatment of CTS is indicated on the basis of electrodiagnostic criteria. DESIGN: More than 2500 claimants who screened positive for CTS were subjected to a formal history, physical examination, and electrodiagnostic studies. A total of 900 subjects were randomly selected for this study. The presence of CTS was determined by a method of comparing median minus ulnar nerve distal latency differential (MUD). RESULTS: There was a statistically significant relationship between CTS and body mass index (P < 0.001), wrist index (P < 0.001), and age (P < 0.001). A total of 43.4% of the participants (391/900) and 38.6% of the wrists (694/1800) had either positive or borderline findings for CTS. There was no difference between the left and right hands. There was no association between job classification and the presence of CTS. Using MUD criteria, more than half of the participants presumed to have CTS did not meet the requirements for diagnosis. Applying the same MUD criteria to all surgical cases, the indication for surgery could not be determined in one-third of the cases (33%, 83/248). CONCLUSIONS: In the population claiming CTS caused by railroad occupations, there was a significant association between CTS and body mass index, age, and wrist index, but not job classification. More than half of the study group and one-third of the surgical subset had normal MUD data.