Resonant antidromic cortical circuit activation as a consequence of high-frequency subthalamic deep-brain stimulation.

Deep brain stimulation (DBS) is an effective treatment of Parkinson's disease (PD) for many patients. The most effective stimulation consists of high-frequency biphasic stimulation pulses around 130 Hz delivered between two active sites of an implanted depth electrode to the subthalamic nucleus (STN-DBS). Multiple studies have shown that a key effect of STN-DBS that correlates well with clinical outcome is the reduction of synchronous and oscillatory activity in cortical and basal ganglia networks. We hypothesized that antidromic cortical activation may provide an underlying mechanism responsible for this effect, because stimulation is usually performed in proximity to cortical efferent pathways. We show with intracellular cortical recordings in rats that STN-DBS did in fact lead to antidromic spiking of deep layer cortical neurons. Furthermore, antidromic spikes triggered a dampened oscillation of local field potentials in cortex with a resonant frequency around 120 Hz. The amplitude of antidromic activation was significantly correlated with an observed suppression of slow wave and beta band activity during STN-DBS. These findings were seen in ketamine-xylazine or isoflurane anesthesia in both normal and 6-hydroxydopamine (6-OHDA)-lesioned rats. Thus antidromic resonant activation of cortical microcircuits may make an important contribution toward counteracting the overly synchronous and oscillatory activity characteristic of cortical activity in PD.

Laparoscopic Pomeroy tubal ligation as a teaching model for residents.

We reviewed our preliminary experience with laparoscopically directed bilateral midtubal resection for tubal ligation (endoscopic Pomeroy) as a potential teaching tool for the acquisition of endoscopic skills during residency training. Thirty-five laparoscopic Pomeroy and 206 banding procedures were reviewed. Age, parity and weight were similar in the two groups. The operative time for banding was reduced slightly after experience with > 10 procedures. In contrast, the operative time for laparoscopic Pomeroy procedures decreased dramatically after individual experience with only a few (< or = 5) procedures. The mean operative time for the Pomeroy group approached that of the more traditional banding technique at five procedures. Our data indicate that laparoscopic Pomeroy sterilization can be an effective teaching tool for operative laparoscopy, allowing residents to repeatedly perform an easy and safe procedure that incorporates basic techniques. Advanced operative endoscopic procedures could then be taught more efficiently after the acquisition of basic skills.

PIP: 25 gynecology residents performed laparoscopic banding (tubal rings) sterilization on 206 women and laparoscopic Pomeroy sterilization on 35 women, all of whom underwent tubal sterilization at the University of Mississippi Medical Center between September 1988 and October 1990. Three faculty members and a fourth year resident retrospectively analyzed the data of both groups to determine the effect of the Pomeroy method on operative laparoscopic skills acquired by the residents during training. Both groups were similar in age, parity, and weight. Each of the 23 residents performed 1-22 laparoscopic banding procedures. As residents gained experience, the time to perform both banding and Pomeroy methods decreased significantly (p = 0.026). After a resident had conducted 5 Pomeroy procedures, the surgery time had approached that of laparoscopic banding. These findings show that gynecology faculty can use laparoscopic Pomeroy tubal ligation as an effective teaching tool for laparoscopy by providing residents an opportunity to repeatedly perform an easy and safe procedure that includes basic techniques. After developing the basic skills, the residents can then learn more efficiently advanced operative endoscopic techniques.

Synoviorthesis with colloidal 32P chromic phosphate for the treatment of hemophilic arthropathy.

Between 1977 and 1992, we performed ninety-two synoviortheses (destruction of synovial tissue by intra-articular injection of a radioactive agent) on forty-eight patients who had a severe congenital disorder of hemostasis and chronic hemophilic synovitis that was resistant to conventional treatment. Colloidal 32P chromic phosphate was injected intra-articularly: 1.0 millicurie for knees and 0.5 millicurie for other joints. The duration of follow-up ranged from one to fifteen years. The frequency and importance of bleeding decreased in most of the patients. The range of motion of half of the joints remained stable or improved and that of the other half continued to decrease. Radiographic scores worsened progressively despite the decreased frequency of hemarthrosis. In most patients, the extra-articular leakage of the radioactive agent was slight. Chromosome breakages were observed almost exclusively in patients who were seropositive for human immunodeficiency virus and in whom the CD4-lymphocyte count was decreased from normal. The patients' level of satisfaction with the results was high.

Acute hereditary coproporphyria induced by the androgenic/anabolic steroid methandrostenolone (Dianabol).

Acute attacks of porphyria can be induced by certain drugs. We report a case of acute coproporphyria induced by methandrostenolone. This is the first report of acute porphyria induced by an androgenic, anabolic steroid.

Abnormal bleeding in the climacteric.

In the perimenopausal years, we encounter a situation where the normal diminution in reproductive capacity, with its resulting disruption of the normal menstrual hormonal pattern, coincides with a very real risk of pelvic pathology. Limitation in the ability to diagnose and to treat these patients conservatively has in the past resulted in a high rate of hysterectomy. With increased understanding of the normal physiology of this stage of transition and with improved diagnostic tools, we are now able to come to a definitive diagnosis in most patients. This ability to assure the diagnosis has made it much easier to counsel the patient confidently about the appropriate course of action. We will continue to encounter the problem of hysterectomy for bleeding with no histologic lesion being found. Although reviewers' letters may be considered an unnecessary thorn in the side, the improved practice that has resulted from these efforts gives strong support to their continued activities. We can have confidence that our treatment plan evolved in a logical manner and offers our patients a high probability of benefit at justifiable risk.

Synoviorthesis with colloidal 32P chromic phosphate for hemophilic arthropathy: clinical follow-up.

Thirty-one synoviortheses were performed in 22 joints of 14 hemophilic patients (aged 12 to 28 years) with chronic synovitis and for whom "conventional treatments" were considered ineffective. Except for patients with inhibitors, conventional treatments included three to six months of adequate prophylactic therapy with the missing coagulation factors, intensive physiotherapy and, when indicated, antiinflammatory agents and orthosis. Colloidal 32P chromic phosphate was injected intraarticularly in doses of 1.0 mCi for knees and of 0.5 mCi for the other joints. Time of follow-up ranged from two to five years. Frequency and importance of bleeding decreased in all patients. Effect on range of motion was best in knees; six of the seven treated improved and one was unchanged. In elbows, flexion-extension was improved in four cases, unchanged in five and decreased in one; pronation-supination was decreased in four cases. Range of motion was not affected in shoulders and ankles except for internal-external rotation which was improved in two of three shoulders treated. The results of 13 synoviortheses in four hemophilic patients with high titer factor VIII inhibitors were comparable to those in hemophiliacs with no inhibitors. However, in three of the four patients synoviorthesis had to be repeated after two to four years for recurrence of synovitis. Extraarticular escape of radioactivity was monitored 62 times for 17 synoviortheses in 12 patients; extraarticular counts never exceeded 4% of the intraarticular counts. Chromosome aberrations were found not to be increased after treatment in the seven patients in whom adequate analysis could be done.