Advances in peripheral nerve repair.

The basic tenets of peripheral nerve repair as outlined in the introduction remain valid. Advances in the field of peripheral nerve repair have become focused on enhancement of the rate, completeness, and accuracy of neural regeneration on a cellular and molecular level. It is hoped that, within the next decade, techniques that have shown promise experimentally will become mainstays of treatment.

Avoidance of transection of the palmar cutaneous branch of the median nerve in carpal tunnel release.

The course of the palmar cutaneous branch of the median nerve (PCBMN) was studied in 25 fresh cadaveric upper extremities in order to identify its relation to local structures and commonly used incisions for carpal tunnel release. The PCBMN was found to closely underlie the thenar crease (average, 0-2 mm radial to crease; range, 6 mm ulnar to 6 mm radial to thenar crease), suggesting that an incision fashioned in the thenar crease would lead to frequent PCBMN injury. The PCBMN was also found to cross the axis of the ring finger when the axis was determined with the finger flexed into the palm. The axis of the ring finger, as drawn with the ring finger extended, projected in a more ulnar direction. The PCBMN was an average of 9 mm radial to this projection (range, 1-16 mm). An analysis of 100 human volunteer hands demonstrated that the deepest point between the thenar and hypothenar eminencies was a constant landmark in the proximal palm (interthenar depression). The PCBMN traveled an average of 5 mm radial to the interthenar depression (range, 0-12 mm radial). Thenar crease anatomy and ring finger projection were highly variable both in absolute location and configuration, providing a poor basis for incision placement. An incision placed approximately 5 mm ulnar to the interthenar depression, extending in the direction of the third web space, will decrease the incidence of injury to the PCBMN.

Acute obstructive sleep apnea as a complication of sphincter pharyngoplasty.

This report describes postoperative airway compromise following sphincter pharyngoplasty (SP) for treatment of post-palatoplasty velopharyngeal dysfunction. A retrospective review of 58 SPs performed for post-palatoplasty velopharyngeal dysfunction, on 30 male, and 28 female patients, over a 5-year study period was undertaken at a tertiary referral academic institution (Washington University School of Medicine), at the St. Louis Children's Hospital, Cleft Palate and Craniofacial Deformities Institute. Eight patients were identified who had the following inclusion criteria: overt perioperative and/or postoperative airway dysfunction, identifiable syndromes, or microretrognathia. Items reviewed were patient demographic factors, associated medical problems, genetics evaluations, nasendoscopic characteristics of velopharyngeal closure, anesthetic evaluation of the patients, and the incidence and severity of perioperative complications. Particular attention was paid to factors contributing to the airway obstruction. Of the eight subjects with perioperative and/or postoperative upper airway dysfunction following SP, five patients had Pierre Robin sequence/micrognathia, while three patients had a history of perinatal respiratory and/or feeding difficulties without micrognathia or an identified genetic disorder. All but two episodes of airway dysfunction resolved within 3 days postoperatively. These patients were discharged home with apnea monitors; both were readmitted with recurrent airway dysfunction. Continuous positive airway pressure (CPAP) was utilized successfully in all instances, and no patients required take-down of the SP to relieve airway dysfunction. CPAP is an effective, noninvasive treatment strategy for management of iatrogenically induced apnea following SP, without sacrificing the surgical benefit of improved speech intelligibility.

Intraneural topography of the ulnar nerve in the cubital tunnel facilitates anterior transposition.

The surgical management of cubital tunnel syndrome includes anterior transposition of the ulnar nerve. The success of all transposition procedures is dependent on placement of the nerve anterior to the medial epicondyle without tension. Fifteen cadaveric upper extremities underwent anterior transposition followed by anterior transposition with separation of the most proximal motor branches from the main ulnar nerve for a distance of 1, 2, and 3 cm. Proximal dissection of these motor branches achieved an average gain in distance from the epicondyle of 71%, with an average distance from the epicondyle of 3.6 cm. The intraneural topography of the ulnar nerve was studied in five additional cases. Cross-section analysis of the fascicular anatomy at 333 microns intervals along the length of the nerve with longitudinal reconstructions confirmed a safe dissection plane without interfascicular plexus formation. The most proximal motor branch in the forearm could be traced proximally an average of 6.7. cm within the nerve before interfascicular mingling occurred (range 6.0 to 7.5 cm). Thus, 6.0 cm represented the upper limit of safe proximal dissection in these nerves. Proximal separation may be performed without disruption of interfascicular plexus connections and will facilitate anterior transposition.

Fascicular topography of the median nerve: a computer based study to identify branching patterns.

This study was undertaken to definitively describe the internal anatomy of the median nerve. Thirty median nerves were dissected in the distal forearm and hand. Sixteen nerves were sectioned every 250 to 1000 microns along their length. Computer programs were developed in our laboratory to digitize and store the data. Analysis of our data has shown the following consistent findings: (1) the number of fascicles remains relatively constant over the centimeter lengths of the nerve; (2) over 75% of the sections contain zero to one fascicular branching; (3) fascicular groups destined for the same endpoint remain localized within the nerve for long distances; and (4) calculation of Wilks' lambda demonstrates a high degree of group fascicular regionality.

Cytogenetics of human sperm: meiotic segregation in two translocation carriers.

Meiotic segregation products were studied in sperm from two men heterozygous for the reciprocal translocations t(8;15)(p22;q21) and t(3;16)(p23;q24). A total of 226 and 201 sperm complements, respectively, were analyzed. In each translocation, 63% of complements were unbalanced, and alternate and adjacent 1 percentages were similar. The 3:1 segregation frequencies produced by the two translocations were 3.5% and 5.0%.

Sperm as an indicator of reproductive risk among petroleum refinery workers.

A questionnaire study of men in a wastewater treatment plant of a petroleum refinery showed twice the rate of fetal loss in the period during employment in the plant compared with the periods before and after. Questions regarding the interpretation of that study and continuing concern about reproductive risk prompted us to perform a cross sectional evaluation of sperm concentration and morphology. After adjustment for an abstinence period, the mean sperm concentration of the 74 unexposed men did not differ significantly from that of the 34 exposed men (79.9 million/cm3 v 68.2 million/cm3, p(1) = 0.16). The two groups also had a similar proportion of sperm with abnormal morphology (49.1% v 44.5%, p(1) = 0.94). This lack of association remained when degree of exposure, age, use of alcohol and marijuana, past illness or fever, use of baths or sauna, and history of urological problems were considered. These results are most consistent with the absence of sperm mediated reproductive problems.

Chromosomes of human sperm: variability among normal individuals.

The chromosomal constitution of 2468 human sperm cells has been investigated by fusion of human sperm with hamster eggs. The overall frequency of cells with structural aberrations was 7.7%, ranging from 1.9% to 15.8%, and varying significantly among individuals. The highest frequency occurred in sperm from the oldest donor (49 years), who also had had a vasectomy reversal three years prior to sampling. The overall aneuploidy frequency was 1.7%, ranging from 0.6% to 3.1%. In nine out of ten donors from whom blood samples were available the frequency of sperm cells with structural aberrations was higher than that for lymphocytes. Two previously reported donors (Brandriff et al. 1984) were resampled after an interval of 14 and 16 months respectively, and were each found to have similar frequencies of sperm chromosome abnormalities at both sampling times. A father-son pair included in the study had several chromosome breakpoints in common, although no more frequently than unrelated individuals.

Chromosomal abnormalities in human sperm: comparisons among four healthy men.

We have used the human-sperm/hamster-egg system to compare the frequencies of structural and numerical chromosomal aberrations in 909 sperm karyotypes from four normal healthy men. The frequency of structural aberrations was 1.3, 4.8, 9.0, and 10.4% respectively in the four donors. Certain specific breakpoints were seen twice or even three times in three of the donors. The incidence of aneuploidy was 1.3, 1.4, 1.4, and 1.9%. In three donors the frequencies of structural aberrations were significantly higher in sperm than in lymphocytes from the same man. X-to-Y ratios did not differ significantly from the expected 50:50.

Active sperm production after cancer chemotherapy with doxorubicin.

The sperm production of 14 cancer patients who received doxorubicin was examined after cessation of therapy. Doxorubicin was used in several multiple-drug protocols for the treatment of various malignancies. Seven patients also received radiotherapy to different sites. Total cumulative doses of doxorubicin ranged from 145 to 625 mg./m.2. Sperm concentration, motility, morphology and the frequency of quinacrine-stained sperm with 2 fluorescent bodies (2F sperm) were measured 7 to 79 months after discontinuation of doxorubicin. Of the patients 6 remained azoospermic, 3 were oligospermic and 5 were normospermic. Sperm motility among the 8 patients with sperm ranged from 20 to 80 per cent. Morphology and 2F sperm distributions were not significantly different from controls. We conclude that, in contrast with the mechlorethamine, vincristine, procarbazine and prednisone protocol, active sperm production within relatively short recovery times is possible after treatment with protocols that include doxorubicin.

High resolution DNA content measurements of mammalian sperm.

The high condensation and flat shape of the mammalian sperm nucleus present unique difficulties to flow cytometric measurement of DNA content. Chromatin compactness makes quantitative fluorescent staining for DNA difficult and causes a high index of refraction. The refractive index makes optical measurements sensitive to sperm head orientation. We demonstrate that the optical problems can be overcome using the commercial ICP22 epiillumination flow cytometer (Ortho Instruments, Westwood, MA) or a specially built cell orientating flow cytometer (OFCM). The design and operation of the OFCM are described. Measurements of the angular dependence of fluorescence from acriflavine stained rabbit sperm show that it is capable of orienting flat sperm with a tolerance of +/- 7 degrees. Differences in the angular dependence for the similarly shaped bull and rabbit sperm allow discrimination of these cells. We show that DNA staining with 4-6 diamidino-2-phenylindole (DAPI) or an ethidium bromide mithramycin combination allows resolution of the X and Y populations in mouse sperm. They have also been successful with sperm from the bull, ram, rabbit, and boar. Reliable results with human sperm are not obtained. The accuracy of the staining and measurement techniques are verified by the correct determination of the relative DNA content of these two populations in sperm from normal mice and those with the Cattanach [7 to X] translocation. Among the potential uses of these techniques are measurement of DNA content errors induced in sperm due to mutagen exposure, and assessment of the fractions of X and Y sperm in semen that may have one population artifically enriched.

Sperm studies in anesthesiologists.

Semen samples were collected from 46 anesthesiologists each of whom had worked a minimum of one year in hospital operating rooms ventilated with modern gas-scavenging devices. Samples collected from 26 beginning residents in anesthesiology served as controls. Concentrations of sperm and percentages of sperm having abnormal head shapes were determined for each sample. No significant differences were found between anesthesiologists and beginning residents. Limiting the analyses to men having no confounding factors (varicocele, recent illness, medications, heavy smoking, frequent sauna use) did not change the results. The sperm concentration and morphology in 13 men did not change significantly after one year of exposure to anesthetic gases. However, the group of mean who had one or more confounding factors (excluding exposure to anesthetic gases) showed significantly higher percentages of sperm abnormalities than did the group of men without such factors. These results suggest that limited exposure to anesthetic gases does not significantly affect sperm production as judged by changes in sperm concentration and morphology. These data are reassuring, but since the hospitals surveyed used modern gas-scavenging devices, men who are occupationally exposed to anesthetic gases without this protection should be studied for fuller assessment of the possible human spermatotoxic effects.

Sperm shape abnormalities in carbaryl-exposed employees.

Semen was collected from 50 men occupationally exposed to carbaryl (1-naphthyl methyl carbamate) in a produciton plant for durations of 1 to 18 years and compared to semen from a control group of 34 unexposed, newly-hired workers. Employment, fertility, health, personal data, and blood samples were collected for each individual. Semen samples were analyzed for changes in sperm count, morphology, and frequency of sperm carrying double flourescent bodies (YFF). As a group, the exposed workers showed a significantly higher proportion of sperm with abnormal head shapes than did the control group (p < 0.005). Age, smoking habits, and medical problems did not appear to affect this result. This finding appears to be limited to men working in the carbaryl production area at the time of sampling. Sperm count and YFF did not show similar differences, which may be because they are known to be statistically less sensitive to small changes. Formerly exposed workers (away from carbaryl for an average of 6.3 years) showed a marginally significant elevation in sperm abnormalities compared to controls (p < .05, one-tailed statistical analyses) suggesting that the increase in abnormal morphology may not be reversible. However, the question of reversibility is sensitive to confounding factors and small sample sizes and, therefore, requires further study. With these data a definitive link between carbaryl exposure and human seminal defects cannot be established. Although a distinct effect on sperm morphology was seen in the exposed group, the increases in sperm shape abnormalities were not related to exposure dose (estimated by number of years on the job or job classification during the year prior to semen collection). Inexplicably, the increases in sperm abnormalities were seen primarily in currently exposed men who had worked with carbaryl for less than approximately 6 years. These findings suggest the need for further study since other workplace-related factor(s) may be responsible for the elevated sperm abnormalities seen in this study.