Faculty Bibliography

There are numerous methods cited in the literature on the treatment of painful neuroma. Nonsurgical methods range from injections with various materials into the nerve end to desensitization of nerve pain conduction pathways. Some surgical treatments aim to alter the environment of the amputated nerve end by transposing it into muscle or bone, others have designed various flaps to protect truncated nerve ends from scar tissue, and still others try to 'cap' the nerve with silicon, a nerve graft, or epineurium to prevent nerve regeneration. All of these methods have proved efficient. However, none of these methods work universally. The authors review the common treatments for painful neuromas. In addition, they review the preliminary results of the extended autologous venous nerve conduit as a novel technique of treating painful neuromas. They also report recent investigations into the pathophysiology of injured nerves

Angiogenesis is essential to both normal and pathological bone physiology. Vascular endothelial growth factor (VEGF) has been implicated in angiogenesis, whereas transforming growth factor-beta1 (TGF-beta1) modulates bone differentiation, matrix formation, and cytokine expression. The purpose of this study was to investigate the relationship between TGF-beta1 and VEGF expression in osteoblasts and osteoblast-like cells. Northern blot analysis revealed an early peak of VEGF mRNA (6-fold at 3 h) in fetal rat calvarial cells and MC3T3-E1 osteoblast-like cells after stimulation with TGF-beta1 (2.5 ng/ml). The stability of VEGF mRNA in MC3T3-E1 cells was not increased after TGF-beta1 treatment. Actinomycin D inhibited the TGF-beta1-induced peak in VEGF mRNA, whereas cycloheximide did not. Blockade of TGF-beta1 signal transduction via a dominant-negative receptor II adenovirus significantly decreased TGF-beta1 induction of VEGF mRNA. Additionally, TGF-beta1 induced a dose-dependent increase in VEGF protein expression by MC3T3-E1 cells (P < 0.01). Dexamethasone similarly inhibited VEGF protein expression. Both TGF-beta1 mRNA and VEGF mRNA were concurrently present in rat membranous bone, and both followed similar patterns of expression during rat mandibular fracture healing (mRNA and protein). In summary, TGF-beta1-induced VEGF expression by osteoblasts and osteoblast-like cells is a dose-dependent event that may be intimately related to bone development and fracture healing

In accessory neuropathy electrodiagnosis, upper trapezius compound muscle action potential (CMAP) latencies and amplitudes are commonly measured. The few prior reports describing middle and lower trapezius recording have traditionally emphasized latency value determination. The utility of amplitude measurement with middle and lower trapezius recording has not, to our knowledge, been previously described in individual patients with accessory neuropathy. We report three patients (A-C) who developed unilateral accessory neuropathy following surgical procedures. Accessory nerve conduction studies were performed with surface recording over the upper, middle, and lower trapezius muscles. Latency values were normal except for a prolonged lower trapezius latency value in patient B. Side-side trapezius amplitude comparisons revealed striking asymmetries from all three recording sites in patients A and B (71-95% CMAP amplitude decrements) and in the lower trapezius recording of patient C. Middle and lower trapezius side-side CMAP amplitude comparisons may increase the sensitivity of accessory neuropathy electrodiagnosis

OBJECTIVES: Routine carpal tunnel electrodiagnosis frequently includes median (MPW) and ulnar (UPW) palm-wrist mixed nerve conduction latency determinations over 8 cm. Despite widespread use, normative palmar latency difference (PLD) and UPW values, and the relative utility of onset latency (OL) or peak latency (PL) measurements are controversial. The current study was conducted to determine normative values for these parameters. METHODS: MPW and UPW studies were performed unilaterally in 33 normal controls. The PLD-OL and PLD-PL were calculated. The mean, range, standard deviation, and upper limits of normal were determined. 74 hands (50 patients) with both clinical and electrophysiologic median neuropathy were also studied. RESULTS: The abnormal MPW and UPW cut-offs were both 1.8 ms (OL), and 2.3 ms (PL). The abnormal PLD cut-offs were 0.5 ms (OL and PL). Using either OL or PL, PLD parameters were similar within controls, and also within CTS patients. Using either OL or PL, UPW parameters were similar between controls and CTS patients. CONCLUSIONS: An abnormal PLD cut-off of 0.5 is recommended. This is slightly higher than some prior recommendations, however it should minimize the likelihood of false positive studies. Onset and peak latency measurements are likely to have similar clinical utility

The causes of prolonged requirement for mechanical ventilation in the intensive care unit (ICU) are currently a subject of investigation. Critical illness polyneuropathy (CIP), an axonal polyneuropathy that frequently occurs with prolonged sepsis and multi-organ failure, has been cited as a frequent cause of difficulty with weaning from a ventilator. The relative contribution of diaphragmatic denervation in ICU patients with and without CIP has not been definitively determined. We reviewed 102 ventilator dependent intensive care unit (ICU) patients. Critical illness polyneuropathy (CIP) was diagnosed based upon electrodiagnostic criteria. Electrodiagnostic studies included diaphragmatic needle electromyography (EMG) to evaluate for diaphragmatic denervation. The medical charts of the patients with diaphragmatic denervation were reviewed for etiologies other than CIP for the diaphragmatic denervation. Our results suggest: 1) Respiratory impairment in ICU patients may often be unrelated to either CIP or diaphragmatic denervation; 2) Only about half of ventilator dependent CIP patients have diaphragmatic denervation; 3) Diaphragmatic denervation in ICU patients frequently may be attributable to causes other than CIP

Among the pathological sequelae of facial paralysis is a paralytic eye. Apart from the psychological and aesthetic deficits, facial paralysis if left untreated can lead to dryness, ulceration and eventual blindness. Although numerous restorative microsurgical approaches have been introduced to address the sequelae of this problem, complete restoration of function to denervated facial muscles remains elusive.Utilizing the rat model of facial paralysis the present research has as an objective to examine a dual treatment approach. Specifically, this study combined the current microsurgical treatment of the cross-facial nerve graft with local administration of insulin-like growth factor I (IGF-I).The efficacy of this combined approach (cross-facial nerve graft + IGF-I) was assessed in the following ways: (a) behavior measurement of the blink response and (b) histomorphometry light and electron microscopy of the entire nerve graft. These data will help provide insight into the restoration of facial muscle function after trauma and assist in the future development of more potent treatment strategies.7he local adnunistration of IGF-I (50 micro g/ml) to the cross-facial nerve graft was found to restore the blink response faster and to strengthen the degree of eye closure. Light microscopy examination revealed that IGF-I significantly enhanced axonal regeneration within a nerve graft (a 22% increase in the mean number of axons), and increased the mean nerve fiber diameter and myelin thickness. Electron microscopy assessment of the nerve grafts demonstrated that the IGF-I treated grafts possessed a greater density of microtubules, which were evenly distributed within the axoplasm

The optimal period of time between peripheral-nerve repair and initiation of limb lengthening procedures has never been precisely determined. In the clinical setting, the surgeon must decide how long the repaired nerves should be allowed to heal before subjecting them to the forces created by the limb-lengthening process. The authors designed a study to quantify and qualify the effects of different recovery periods between initial nerve repair and subsequent limb-lengthening via distraction osteogenesis. Forty-two Sprague-Dawley male rats were randomized in two different categories of nerve repair: end-to-end and nerve grafts. At 4, 8 and 12 weeks after nerve reconstruction, the femur was submitted to limb-lengthening at a rate of 1 mm/day (0.25 mm every 6 hr). Sciatic Function Index (SFI) evaluation indicated that the impact of distraction was detrimental in the grafted nerves, although they maintained their electrical and morphologic properties at comparable levels to the non-distracted nerves. Nerves with direct coaptation presented an overall superior regeneration pattern. The findings in end-to-end repairs distracted at 8 weeks and those of grafted nerves at 12 weeks were comparable to those in distracted normal nerves. The morphology of the distracted nerves appeared to be more organized than that observed in the non-distracted nerves