Internal auditory canal involvement of acoustic neuromas: surgical correlates to magnetic resonance imaging findings.

OBJECTIVE: Factors that play a role in the selection of surgical approach for acoustic neuromas include patient health and age, size of tumor, hearing status, and location of tumor in the internal auditory canal (IAC) and the cerebellopontine angle. Deep extension into the IAC makes hearing preservation extremely difficult when a retrosigmoid craniotomy is used, and the best approach is a middle fossa subtemporal route. Modern gadolinium-enhanced magnetic resonance imaging (MRI) can be inaccurate in identifying the presence of tumor laterally in the IAC. This may affect the selection of a surgical approach. STUDY DESIGN: This study was a retrospective case review. SETTING: Patients were accrued from a tertiary referral otologic practice. PATIENTS: From 1997 through 2000, the authors identified six patients who had undergone acoustic neuroma surgery, had adequate imaging and intraoperative data, and demonstrated a lack of correlation between MRI and intraoperative findings of the lateral IAC. INTERVENTION: The interventions were preoperative MRI of the IAC and surgical resection of an acoustic neuroma. MAIN OUTCOME MEASURE: Comparison of MRI and intraoperative findings of the lateral IAC were the main outcome measures. RESULTS: Six patients demonstrated a lack of correlation between MRI and intraoperative findings of the lateral IAC. CONCLUSIONS: Gadolinium-enhanced T1-weighted MRI findings of the depth of penetration into the lateral aspect of the IAC do not always correlate with intraoperative findings and thus may have implications in the selection of surgical approaches to acoustic neuromas.

Morphology and Development of Odostomia columbiana Dall and Bartsch (Pyramidellidae): Implications for the Evolution of Gastropod Development.

Although pyramidellid gastropods are a phylogenetically important group of diverse and abundant ectoparasites, little is known about their life histories. Herein, we describe the adult morphology and development of the pyramidellid Odostomia columbiana, which parasitizes the scallops Chlamys hastata and C. rubida in the Northeast Pacific. Anatomically, adult O. columbiana resemble other known pyramidellids although they lack the tentacular pads typical of other Odostomia species. Embryonic development is similar to that described for other pyramidellids: cleavage is unequal, gastrulation is partially by invagination, and considerable growth occurs before hatching. However, embryonic and larval development are much slower than for other described species. The planktotrophic larvae hatch after 19 days of intracapsular development and metamorphose about 2 months later. O. columbiana veligers have a large black pigmented mantle organ to the right of the midline, a distinct metapodial tentacle, and three or four long bristles that project over the operculum from behind the foot. Observations of newly metamorphosed juveniles suggest that previous disagreements regarding the development of heterostrophy are due to variation in the degree of heterostrophy among species. Our observations also generally corroborate certain scenarios explaining the evolution of gastropod cleavage type and larval heterochrony. Unequal cleavage and larvae that hatch without well-developed eyes and tentacles may be characteristic of the common ancestor of pyramidellids and opisthobranchs; however, late development of the larval heart is probably a derived condition of opisthobranchs.

Maxillary molar vertical control with the use of transpalatal arches.

Upper molar eruption and its clinical significance to vertical control were measured in a retrospective cephalometric study of 40 patients (20 with and 20 without transpalatal arches) treated in a private practice. Pretreatment and posttreatment cephalometric values were compared to determine how well the patients were matched. No statistically significant differences were noted between control and test groups for the following variables: maxillary and mandibular molar vertical eruption per year, maxillary complex vertical growth per year, effective horizontal condylar growth per year, ratio of effective horizontal pogonion movement to effective vertical pogonion movement, ratio of effective vertical condylar growth to the summation of maxillary, and mandibular vertical molar eruption plus maxillary complex vertical growth, beginning age, and ending age. The control group exhibited statistically greater forward positioning of pogonion and greater effective vertical condylar growth than did the treatment group.

Mitomycin-compatible suture technique for fornix-based conjunctival flaps in glaucoma filtration surgery.

An overlying vertical mattress suture of 9-0 nylon, running the length of the conjunctival edge and anchored to an intact limbus at each end, allows very leak-resistant closure of fornix-based conjunctival flaps. Use of a taper needle with a tiny cutting tip prevents leakage at suture holes. The distance between suture holes in the conjunctival flap must be less than the length of the corresponding limbal anchor bite to hold the conjunctival edge flat where the suture does not overlie the edge. In 153 operations using mitomycin C intraoperatively, one of 78 eyes that had undergone primary trabeculectomy or cataract-trabeculectomy surgery and 18 of 75 eyes that had undergone trabeculectomy after other surgeries had temporary leaks along the suture line, but only two of these leaks persisted and required surgical repair. This technique allows filtration surgery to be performed in areas of scarred or recessed conjunctiva that are not suitable for limbus-based flaps.

Treatment of chronic postfiltration hypotony by intrableb injection of autologous blood.

OBJECTIVE: To treat chronic hypotony with decreased vision after filtration surgery. DESIGN: After observation from 3 1/2 to 13 months with no spontaneous improvement, eyes were treated with the experimental therapy and followed up closely to determine the results. PATIENTS: Four eyes with chronic hypotony, selected from a series of 125 eyes receiving trabeculectomy augmented by intraoperative mitomycin. All eyes had posterior chamber pseudophakia. All eyes had postoperative laser cutting of sutures holding the scleral flap of the trabeculectomy. INTERVENTION: After administration of topical prophylactic 0.3% ciprofloxacin hydrochloride and topical anesthetic, the bleb was inflated with whole autologous blood through a 27-gauge needle passed subconjunctivally into the bleb. MAIN OUTCOME MEASURES: Change in intraocular pressure, change in vision, change in choroidal detachment, any type of complication. RESULTS: Average intraocular pressure increased from 5.5 to 8.2 mm Hg. Average vision improved from 20/148 to 20/33. In two eyes with choroidal detachment, the detachment absorbed in one eye and decreased in the other. No complications occurred. CONCLUSION: Intrableb injection of autologous blood deserves further study as a possible treatment for hypotony following filtration.

Low-energy linear-incision neodymium: YAG laser iridotomy versus linear-incision argon laser iridotomy. A prospective clinical investigation.

When the Q-switched neodymium: YAG (Nd: YAG) laser is focused through the Wise 103-diopter (D) iridotomy-sphincterotomy lens (103-D lens) at low energy levels, the peripheral iris fibers can be cut individually across the iris tension lines to produce large iridotomies of controllable size. Thirty patients had linear-incision Nd:YAG laser iridotomy in one eye and linear-incision argon laser iridotomy in the other. Two-hour post-laser IOP rises averaged 7.33 mmHg for the Nd:YAG laser and 8.64 mmHg for the argon laser. The argon laser produced lens burns in 9 of 30 eyes, including 7 of 9 blue eyes. No lens damage occurred with the Nd:YAG laser. No corneal or retinal damage was seen with either laser. Local oozing of blood inhibited optical breakdown and required a pause before completion in 5 of 30 eyes with Nd:YAG iridotomy, including 4 of 6 dark brown thick irides. Because the iris fibers must be cut by direct contact with the laser plasma, serial cutting of iris fibers by multiple low-energy plasmas is safer than a single-shot, high-power plasma occupying the full thickness of the iris. Because it is effective and because it avoids the hazards of argon laser iridotomy and of high-power Nd:YAG laser iridotomy, linear incision Nd:YAG laser iridotomy is recommended as the safest method of iridotomy.

Ten year results of laser trabeculoplasty. Does the laser avoid glaucoma surgery or merely defer it?

The first 150 consecutive phakic eyes from 113 patients aged 40 years or more treated with laser trabeculoplasty were evaluated. Twenty-four patients (37 eyes) have died, two eyes developed spontaneous rubeosis, and one patient (one eye) was not available, leaving 110 eyes with a 6 to 10 years follow-up. Of the 37 eyes of dead patients (average age 80 years), only one eye had filtering surgery, and 33 of the other 36 eyes had a last recorded intraocular pressure of less than 21 mm Hg. Of the 110 eyes of living patients followed for 6 years, 33 had filtering surgery and 62 eyes (56 per cent) had an intraocular pressure of less than 21 mm Hg. Of 10 eyes followed for 10 years, eight had intraocular pressures less than 23 mm Hg, seven had pressures less than 21 mm Hg, and two had had filtering surgery. Eyes with advanced disc damage at the time of trabeculoplasty had a 51 per cent rate of later glaucoma surgery, while eyes with a cup/disc ratio less than 0.9 at trabeculoplasty had a glaucoma surgery rate of 16 per cent. Eyes of non-white patients did as well as eyes of white patients. Computer analysis of over 1,700 eyes with two-year follow-up indicated better long-term control when 100 or more laser burns were used for trabeculoplasty. Laser trabeculoplasty can defer surgery for the remaining lifespan in elderly patients, and has controlled primary open-angle glaucoma for over 10 years, but later glaucoma surgery is often required in eyes with far advanced glaucoma damage.

Large iridotomies by the linear incision technique using the neodymium:YAG laser at low energy levels. A study using cynomolgus monkeys.

Multiple Q-switched neodymium:YAG (Nd:YAG) laser impacts at energy levels of 1.0 to 1.7 mJ, focused on the iris through the 103-diopter (D) iridotomy-sphincterotomy lens, were applied back and forth in a line across the radial fibers of the mid-peripheral iris in eyes of the cynomolgus monkey (Macaca fasicularis) to produce large iridotomies of controllable size. Oozing of blood was minimal and no lens capsule damage occurred. These iridotomies showed less iris concussion damage than did conventional Nd:YAG laser iridotomies made by directing high-energy laser shots through the Abraham lens upon a single iris spot.

A high-efficiency laser iridotomy-sphincterotomy lens.

A new laser iridotomy-sphincterotomy contact lens, bearing a 103-diopter optical button decentered 2.5 mm, gives the smallest iris focal spot and highest iris energy density practicably obtainable with a single optical glass refracting surface placed upon a thin Goldmann-type contact lens. By increasing iris energy density to a level 7.79 times greater than that from a plano contact lens and 2.92 times greater than that from the Abraham lens, the lens increases the iris burn temperature level above the threshold level for evaporative pyrolysis, even at exposures of 0.01 and 0.02 second, thus facilitating argon laser iridotomy and iris sphincterotomy by the linear incision method. Corneal and retinal energy exposures are greatly reduced. Used with the Nd-YAG laser, the lens increases efficiency for iridotomy and for division of vitreous bands in the anterior chamber.

Iris sphincterotomy, iridotomy, and synechiotomy by linear incision with the argon laser.

Linear cuts can be made across the iris fibers by multiple 0.01- to 0.05-second duration argon laser burns delivered through an Abraham iridectomy lens. Intrinsic iris tension will then cause the linear cuts to spread apart. This allows enlargement, reshaping, or repositioning of the pupil and large laser iridotomies with minimal burn energies and a very high percentage of success. The technique minimizes risk to the retina and eliminates the need for stretch burns in laser iridotomy. It requires the use of the Abraham lens and an argon laser, which generates a small spot of high power density. Posterior synechiae can be incised by using a line of low-power 0.01- or 0.02-second burns applied to the adherent pigment epithelium along the iris margin.

Errors in laser spot size in laser trabeculoplasty.

By microscopic examination of 50-micron laser burns made on orange paper at different eye-piece settings of the slit-lamp microscope, 27 commercial argon lasers were evaluated for accuracy of 50-micron spot size and for coincidence of the aerial focal points of the laser and the microscope. Only four lasers (14%) produced a spot less than 70 microns diameter (double the area of a 50-micron spot) with the eye-pieces set on zero. With the eye-pieces focussed for minimum spot size, 12 lasers (44%) still gave a minimum spot of 70 microns or more, and four of those gave a spot of 100 microns or more. Improperly focussed lasers and oversize laser spots are a major problem in laser trabeculoplasty.

Long-term control of adult open angle glaucoma by argon laser treatment.

Uncontrolled adult open angle glaucoma was treated with a new argon laser technique in which 100 spots are applied 360 degrees around the trabecular meshwork. The average pressure drop was 12.7 mm Hg in 105 eyes at one year, 11.5 mm Hg in 59 eyes at two years, 11.3 mm Hg in 25 eyes at three years, and 13.3 mm Hg in 11 eyes at four years. Only 6% of the eyes required additional surgery. The rate of control was equivalent to trabeculectomy, but with far fewer complications. Control in blacks and in patients over age 70 was better (91%) than with surgical procedures. Microscopic examination of two controlled eyes showed no trabecular punctures. The laser microscars reduce the diameter of the trabecular ring, tightening the meshwork, and restoring function to the normal outflow systems.