Joseph C. Milbrandt

Bilateral gluteal compartment syndrome following robotic-assisted prostatectomy.

Bilateral gluteal compartment syndrome is a rare condition. Only 6 previous cases have been reported in the literature. Two previous cases involved positioning for urological procedures, while the other cited causes of bilateral gluteal compartment syndrome include exercise-induced, trauma, and prolonged immobilization from substance abuse. The 2 previously published reports of bilateral gluteal compartment syndrome associated with urologic positioning were treated conservatively due to late presentation and onset of rhabdomyolysis. This article presents a case of a 61-year-old man who developed bilateral gluteal compartment syndrome following prolonged urologic surgery in a dorsal lithotomy position. Orthopedic evaluation revealed physical examination findings and intracompartment pressures consistent with bilateral gluteal compartment syndrome. He underwent bilateral gluteal compartment fasciotomies. An expansile-type Kocher Langenbach incision was made, extending from lateral to the posterior superior iliac spine inferior to the level of the greater trochanter. The 3 compartments were decompressed bilaterally. At completion, the compartments showed definite objective softening. He was treated with delayed closure of his fasciotomy wounds. He was discharged home on sixth postoperative day 6. His wounds healed without difficulty and he regained normal strength and sensation in his lower extremities. Gluteal compartment syndrome following surgery is a preventable condition. Prevention should center on intraoperative padding and positioning, intraoperative repositioning, and restricting the length of the procedure. Once it is identified, early diagnosis and treatment can prevent long term complications.

Central auditory aging: GABA changes in the inferior colliculus

Age-related hearing loss (presbycusis) is a complex state that reflects pathologic changes along the entire auditory neuraxis. Loss of speech understanding, decreased ability to localize sounds, and a decreased ability to detect and extract signals in noise are characteristic problems encountered by the elderly. Central (neural) presbycusis frequently results in a dramatic loss in speech understanding without a parallel change in pure-tone thresholds. In spite of evidence that suggests these deficits cannot be fully explained by peripheral changes alone, few studies have examined the neurochemical basis of central auditory dysfunction in aging. Age-related alterations in neural circuits involved in the processing of acoustic information could reflect changes in the synthesis, degradation, uptake, release, and receptor sensitivity of neurotransmitters, perhaps secondary to cell loss and/or progressive deafferentation. A series of studies designed to test this hypothesis has examined aging in the central auditory system of the F344 rate. Age-related changes associated with GABA neurotransmitter function in an important auditory midbrain structure, the inferior colliculus, have been investigated. These studies found: (1) decreased numbers of GABA immunoreactive neurons; (2) decreased basal levels (concentrations) of GABA; (3) decreased GABA release; (4) decreased glutamic acid decarboxylase activity; (5) decreased GABAB receptor binding; (6) decreased numbers of presynaptic terminals; and (7) subtle GABAA receptor binding changes. Collectively, these age-related changes suggest altered GABA neurotransmitter function in the IC. Identification of specific neurotransmitter changes in structures important in speech processing could eventually lead to the development of pharmacotherapy for selective types of age-related hearing loss.

GAD levels and muscimol binding in rat inferior colliculus following acoustic trauma

Pharmacological studies of the inferior colliculus (IC) suggest that the inhibitory amino acid neurotransmitter gamma-aminobutyric acid (GABA) plays an important role in shaping responses to simple and complex acoustic stimuli. Several models of auditory dysfunction, including age-related hearing loss, tinnitus, and peripheral deafferentation, suggest an alteration of normal GABA neurotransmission in central auditory pathways. The present study attempts to further characterize noise-induced changes in GABA markers in the IC. Four groups (unexposed control, 0 h post-exposure, 42 h post-exposure, and 30 days post-exposure) of 3-month-old male Fischer 344 rats were exposed to a high intensity sound (12 kHz, 106 dB) for 10 h. Observed hair cell damage was primarily confined to the basal half of the cochlea. There was a significant decrease in glutamic acid decarboxylase (GAD(65)) immunoreactivity in the IC membrane fraction compared to controls (P<0.05) at 0 h (-41%) and 42 h (-28%) post-exposure, with complete recovery by 30 days post-exposure (P>0.98). Observed decreases in cytosolic levels of GAD(65) were not significant. Quantitative muscimol receptor binding revealed a significant increase (+20%) in IC 30 days after sound exposure (P<0.05). These data suggest that changes in GABA neurotransmission occur in the IC of animals exposed to intense sound. Additional studies are needed to determine whether these changes are a result of protective/compensatory mechanisms or merely peripheral differentiation, as well as whether these changes preserve or diminish central auditory system function.

Age-related changes in brainstem auditory neurotransmitters: Measures of GABA and acetylcholine function

This study was designed to determine if there are age-related alterations in the bio-synthetic enzyme glutamic acid decarboxylase (GAD), the degradative enzyme GABA-transaminase (GABA-T), and the uptake system for GABA in the central nucleus of the inferior colliculus (CIC), the cochlear nucleus (CN), and/or nuclei of the lateral lemniscus (NLL) of Fischer-344 rats. For purposes of comparison, the cholinergic neuronal system was studied in parallel in young adult (3-7 months), mature (15-17 months) and aged (24-26 months) rats. In young adults GAD activity was highest in the CIC (219 nmol/mg protein/h; N = 5), intermediate in NLL (82 nmol/mg protein/h), and lowest in CN (34 nmol/mg protein/h). Choline acetyltransferase (ChAT) activity was highest in NLL and CN, and approximately 35-40% lower in CIC. A more uniform pattern was observed with GABA-T activity. Reductions in GAD activity were seen in the CIC of mature (-31%) and aged (-30%) rats that were not graded with age when compared to young adult, P < 0.05 (N = 5). This effect was regionally selective, since the CN did not show any loss of GAD or ChAT activity. The neurotransmitter selectivity of this deficit in CIC is supported by the non-parallel changes in ChAT activity (-22%, aged vs. mature, P < 0.05) that occurred after the changes in GAD activity. In contrast to the loss of GABAergic biosynthetic capacity in aged CIC, high affinity uptake processes (Kd and Vmax) for 14C-GABA and 3H-D-aspartate were not significantly altered (P > 0.05). Similar to the CIC, the NLL showed remarkable age-related deficits, but these deficits were more substantial for the cholinergic system (ChAT activity: -56% aged vs. young adult, P < 0.05; GAD activity: -35% aged vs. mature). None of the areas examined showed a significant loss of GABA-T activity with aging. These data suggest: 1) Age-related loss of GABA-mediated inhibition in the CIC of Fischer-344 rats is not attributable to changes in uptake or degradation of GABA, but may be related loss of biosynthetic capacity (i.e. activity or quantity) of the GAD present; 2) processing centers of the central auditory pathway (i.e. CIC and NLL), but not necessarily primary (i.e. CN) integrative nuclei, demonstrate selective, age-related neurochemical deficits; and 3) age-related neurochemical changes in central auditory structures may contribute substantially to the abnormal perception of signals in noise and loss of speech discrimination observed in neural presbycusis.

Multi-modal, pre-emptive analgesia decreases the length of hospital stay following total joint arthroplasty.

Traditional treatment of pain following total joint arthroplasty involves postoperative oral narcotic medications and intravenous patient-controlled analgesia, both of which can result in significant postoperative morbidity. Multi-modal analgesia involving >or=2 classes of drugs acting on different receptor types may be as effective as single-narcotic/patient-controlled analgesia with fewer analgesic-related side effects. In addition, administering analgesia prior to surgery (pre-emptive) may reduce postoperative pain intensity. The current study was designed to compare the impact of multi-modal pre-emptive analgesia versus patient-controlled analgesia on postoperative nausea, rehabilitation participation, and length of stay following total joint arthroplasty. A retrospective chart review and comparison was performed for patients undergoing total joint arthroplasty who received either postoperatively patient-controlled analgesia or pre-emptive analgesia (scheduled postoperative oxycodone and a COX-2 inhibitor). Length of hospital stay for the pre-emptive group averaged 2.74 vs 3.28 days for patient-controlled analgesia patients. The patient-controlled analgesia group consumed significantly more intravenous morphine (17.7 mg vs 7.2) and experienced a three-fold increase in nausea. In addition, the patient-controlled analgesia group was twice as likely to miss therapy and nearly 2 times more likely to be discharged to an extended care facility. The use of pre-emptive oxycodone and a selective COX-2 inhibitor decreased postoperative narcotic requirements and increased participation in rehabilitation. In addition, patients receiving pre-emptive analgesics had a decreased hospital length of stay and reduced likelihood of discharge to a skilled nursing facility. These data support the continued study and use of pre-emptive multi-modal analgesia paradigms in this population.

Alterations of GABAA receptor subunit mRNA levels in the aging Fischer 344 rat inferior colliculus

The inhibitory neurotransmitter, γ‐aminobutyric acid (GABA) is critically involved in shaping neuronal responses to simple and complex acoustic stimuli in the central auditory structure, the inferior colliculus (IC). Studies in rat and human suggest that age‐related changes in markers for GABA neurotransmission occur in the IC. In particular, these changes include findings indicative of an age‐related increase in the efficacy/potency of GABA to inhibit changes in GABAA receptor modulation suggest the potential for an alteration in GABAA receptor subunit composition in the old rat IC. To test this idea, the present study used in situ hybridization to quantify age‐related changes in GABAA receptor subunit mRNA levels in the three major subdivisions of the IC in the F344 rat: dorsal cortex (DCIC), external cortex (ECIC), and the central nucleus (CIC).

Glycine immunoreactivity and receptor binding in the cochlear nucleus of C57BL/6J and CBA/CaJ mice: Effects of cochlear impairment and aging

Glycinergic neurons in the cochlear nucleus (CN) of C57BL/6J (C57) and CBA/CaJ (CBA) mice were studied by using immunocytochemical and receptor‐binding techniques. Adult C57 mice exhibit progressive cochlear pathology as they age, whereas aging CBA mice retain good hearing. In the CN of old C57 mice (18 months) with severe hearing loss, the number of glycine‐immunoreactive neurons decreased significantly. The number (Bmax) of strychnine‐sensitive glycine receptors (GlyR) decreased significantly in the dorsal CN of old C57 mice. Significant effects were not observed in the CN of middle‐aged C57 mice (with less‐severe hearing loss) or in very old CBA mice (which do not exhibit severe hearing loss). The data suggest that the combination of severe hearing loss and old age results in deficits in one or more inhibitory glycinergic circuits in the CN. J. Comp. Neurol. 385:405–414, 1997.

Impact of the 80-hour workweek on surgical exposure and national in-training examination scores in an orthopedic residency program.

OBJECTIVES This study examines the impact of the 80-hour workweek on the number of surgical cases performed by PGY-2 through PGY-5 orthopedic residents. We also evaluated orthopedic in-training examination (OITE) scores during the same time period. METHODS Data were collected from the Accreditation Council for Graduate Medical Education (ACGME) national database for 3 academic years before and 5 years after July 1, 2003. CPT surgical procedure codes logged by all residents 3 years before and 5 years after implementation of the 80-hour workweek were compared. The average raw OITE scores for each class obtained during the same time period were also evaluated. Data were reported as the mean +/- standard deviation (SD), and group means were compared using independent t-tests. RESULTS No statistical difference was noted in the number of surgical procedure codes logged before or after the institution of the 80-hour week during any single year of training. However, an increase in the number of CPT codes logged in the PGY-3 years after 2003 did approach significance (457.7 vs 551.9, p = 0.057). Overall, the average number of cases performed per resident increased each year after implementation of the work-hour restriction (464.4 vs 515.5 cases). No statistically significant difference was noted in the raw OITE scores before or after work-hour restrictions for our residents or nationally. CONCLUSIONS We found no statistical difference for each residency class in the average number of cases performed or OITE scores, although the total number of cases performed has increased after implementation of the work-hour restrictions. We also found no statistical difference in the national OITE scores. Our data suggest that the impact of the 80-hour workweek has not had a detrimental effect on these 2 resident training measurements.

Surgical Simulators and Hip Fractures: A Role in Residency Training?

BACKGROUND Orthopedic surgery residency training requires intellectual and motor skill development. In this study, we utilized a computer-based haptic simulator to examine a potential model for evaluation of resident proficiency and efficiency in the placement of a center guide wire during fixation of an intertrochanteric proximal femur fracture. We hypothesize the junior residents will utilize more fluoroscopy and require more time to complete the task. METHODS Postgraduate year (PGY) 1-5 residents completed the same task of placing a single central guide pin into a femoral head for a dynamic hip screw construct utilizing a haptic surgical simulator. Residents were divided into 2 groups (PGY 1-2 and PGY 3-5) and then evaluated based on final tip-apex distance (TAD), fluoroscopy time, time to complete the task, total number of distinct attempts at pin placement for each femur construct, as well as final 3-dimensional location of the pin from the isometric center of the femoral head. RESULTS No statistically significant differences were noted between the 2 groups in total time or for tip-apex distance, anterior/posterior medial/lateral position, anterior/posterior superior/inferior, and lateral x-ray medial/lateral positioning measurements. Significant differences between Groups I and II were observed in anterior/posterior final position on the lateral view (p = 0.01), unique attempts (0.77 and 1.5, p = 0.03), and total fluoroscopic time (18.4 seconds and 12.9 seconds, p = 0.05). CONCLUSIONS In this study, we displayed that based on our simulator model there was no statistical difference between Group I and II in time to completion, final placement on anterior/posterior (A/P) view, and tip-apex distance. There was a statistically significant difference in the anterior/posterior placement of the wire in lateral view between the 2 groups, fluoroscopy time, and number of attempts per trial. Our findings suggest a computer-based surgical simulator can identify measurable differences in surgical proficiency between junior and senior orthopedic surgery residents and may play an expanding role in resident education.

Age-related changes in [3H]strychnine binding in the vestibular nuclei of rats

Glycine plays an important role as a neurotransmitter in the four vestibular nuclei (VN). The objective of this study was to determine if the levels of glycine-receptor binding in the VN change as a function of age. Quantitative receptor autoradiography was performed on brainstem sections from three age groups (3, 18 and 26 months) of Fischer 344 rats to assess binding in the VN. Glycine receptors were localized using [3H]strychnine binding. Strychnine binding declined monotonically with increasing age, such that the level of strychnine binding in each of the VN in the 28-month-old animals was approximately one-half that in the 3-month-olds. The age-related decrease in levels of strychnine binding suggest altered glycinergic function in the VN, which may in turn contribute to disturbances in equilibrium observed in the elderly.