The use of compound muscle action potentials (CMAP) for postoperative monitoring of free functioning gracilis muscle transfer: A preliminary report.

BACKGROUND AND PURPOSES: The use of skin flap as a monitoring tool cannot sensitively reflect the vascularity of a functioning free muscle transfer (FFMT), and it may result in delayed detection of vascular compromise. We report the use of compound muscle action potentials (CMAPs) as a supplemental method in the monitoring of free gracilis transfers. SUBJECTS AND METHODS: In 46 successful free gracilis transfers in 23 patients following total brachial plexus injury (BPI), CMAPs were measured every hour for 75 h postoperatively. We analyzed the amplitude, latency, and duration to understand the Wallerian degeneration effect and thresholds to warn vascular compromise clinically. After the primary study, we applied CMAP monitoring for 23 clinical cases. MAIN FINDINGS: Three basic wave patterns of the CMAPs with or without dispersion were recognized. Forty-two CMAPs were successfully traced and 27 CMAPs with one constant wave pattern showed two types of amplitude and latency changes; positive and negative Wallerian degeneration. The mean 1-h maximal decreases of amplitudes and elongation of latency were 36% and 77%, respectively; however, they returned to the original pattern within 1 h. There were no significant differences of reinnervation time and final strength of elbow flexion between these 46 muscle transfers. In the clinical series, we experienced two cases of vascular compromise that showed CMAP critical alterations without skin flap changes. CONCLUSIONS: Our preliminary results show that the measurement of CMAPs has great potential for the sensitive and reliable monitoring of muscle circulation after FFMT. The clinical critical values of CMAP amplitude changes for vascular compromise are >40% sudden decrease, and they continued to decrease further. This technique is most useful for postoperative vascular monitoring of a buried muscle flap, and it is proven to be of clinical significance in current vascular compromised cases. LEVEL OF EVIDENCE: Level Ⅳ, Case Series.

Reconstruction of shoulder and elbow function using multiple muscle transfers for cervical spondylotic amyotrophy.

STUDY DESIGN: This was a retrospective study of 8 patients with cervical spondylotic amyotrophy who underwent multiple muscle transfers. OBJECTIVE: The purpose of this study was to evaluate results of multiple muscle transfers about the shoulder and elbow in patients with cervical spondylotic amyotrophy. SUMMARY OF BACKGROUND DATA: Cervical spondylotic amyotrophy is characterized by severe muscle atrophy of the shoulder girdle and elbow. Even after cervical spine surgery, many patients have poor shoulder and elbow function. METHODS: Multiple muscle transfer procedures including the transfer of trapezius, pectoralis major, latissimus dorsi muscles, and the Steindler procedure for reconstruction of shoulder and elbow function were performed in 8 patients with cervical spondylotic amyotrophy. Patients were evaluated at a mean of 18.2 months (range, 5-75 mo). RESULTS: All 8 patients obtained satisfactory functional recovery with improvement of active range of motion without any systemic and local complications within 3 to 6 months postoperatively. Patients at the last follow-up had obtained a mean of 91° of shoulder abduction, 111° of shoulder flexion, 23° of external rotation and 110° of elbow flexion. Disability scores (Japanese version) of the arm, shoulder, and hand improved by a mean of 28 points. CONCLUSION: Multiple muscle transfers can improve shoulder and elbow function in cervical spondylotic amyotrophy, in cases of not only poor outcome after cervical surgery, but also in advanced paralysis. It is a useful set of procedures even in old patients, and provides definitive functional improvement of shoulder and elbow function from 3 to 6 months. LEVEL OF EVIDENCE: 4.

Postoperative monitoring in free muscle transfers for reconstruction in brachial plexus injuries.

Free gracilis transfers are done for reanimation of the upper limb in traumatic total brachial plexus palsy. Because of buried nature of the free muscle and monitoring skin flap in the axillary or infraclavicular region, it is always a tricky situation for continuous and repeated monitoring to assess vascular status. Critical ischemia times vary between the muscle and monitoring skin flap because of which signs of ischemic changes in the monitoring skin flap are always delayed with respect to the muscle. We describe a novel method that uses the principle of evoked potentials from the muscle to assess the vascular status of the free muscle and detects vascular compromise early before the skin changes are apparent.

Sequential immunization with V3 peptides from primary human immunodeficiency virus type 1 produces cross-neutralizing antibodies against primary isolates with a matching narrow-neutralization sequence motif.

An antibody response capable of neutralizing not only homologous but also heterologous forms of the CXCR4-tropic human immunodeficiency virus type 1 (HIV-1) MNp and CCR5-tropic primary isolate HIV-1 JR-CSF was achieved through sequential immunization with a combination of synthetic peptides representing HIV-1 Env V3 sequences from field and laboratory HIV-1 clade B isolates. In contrast, repeated immunization with a single V3 peptide generated antibodies that neutralized only type-specific laboratory-adapted homologous viruses. To determine whether the cross-neutralization response could be attributed to a cross-reactive antibody in the immunized animals, we isolated a monoclonal antibody, C25, which neutralized the heterologous primary viruses of HIV-1 clade B. Furthermore, we generated a humanized monoclonal antibody, KD-247, by transferring the genes of the complementary determining region of C25 into genes of the human V region of the antibody. KD-247 bound with high affinity to the "PGR" motif within the HIV-1 Env V3 tip region, and, among the established reference antibodies, it most effectively neutralized primary HIV-1 field isolates possessing the matching neutralization sequence motif, suggesting its promise for clinical applications involving passive immunizations. These results demonstrate that sequential immunization with B-cell epitope peptides may contribute to a humoral immune-based HIV vaccine strategy. Indeed, they help lay the groundwork for the development of HIV-1 vaccine strategies that use sequential immunization with biologically relevant peptides to overcome difficulties associated with otherwise poorly immunogenic epitopes.

Preparation of recombinant alpha-thrombin: high-level expression of recombinant human prethrombin-2 and its activation by recombinant ecarin.

We have established a large-scale manufacturing system to produce recombinant human alpha-thrombin. In this system, a high yield of alpha-thrombin is prepared from prethrombin-2 activated by recombinant ecarin. We produced human prethrombin-2 using mouse myeloma cells and an expression plasmid carrying the chicken beta-actin promoter and mutant dihydrofolate reductase gene for gene amplification. To increase prethrombin-2 expression further, we performed fed-batch cultivation with the addition of vegetable peptone in 50 liters of suspension culture. After five feedings of vegetable peptone, the expression level of the recombinant prethrombin-2 reached 200 micro g/ml. Subsequently, the recombinant prethrombin-2 could be activated to alpha-thrombin by recombinant ecarin expressed in a similar manner. Finally, recombinant alpha-thrombin was purified to homogeneity by affinity chromatography using a benzamidine-Sepharose gel. The yield from prethrombin-2 in culture medium was approximately 70%. The activity of the purified recombinant alpha-thrombin, including hydrolysis of a chromogenic substrate, release of fibrinopeptide A, and activation of protein C, was indistinguishable from that of plasma-derived alpha-thrombin. Our system is suitable for the large-scale production of recombinant alpha-thrombin, which can be used in place of clinically available alpha-thrombin derived from human or bovine plasma.

Nerve root distribution of deltoid and biceps brachii muscle in cervical spondylotic myelopathy: a potential risk factor for postoperative shoulder muscle weakness after posterior decompression.

To investigate the nerve root distribution of deltoid and biceps brachii muscle, compound muscle action potentials (CMAPs) were recorded intraoperatively following nerve root stimulation in cervical spondylotic myelopathy. A total of 19 upper limbs in 12 patients aged 55-72 years (mean, 65.5 years) with cervical spondylotic myelopathy were examined. CMAPs were recorded from deltoid and biceps brachii muscle following C5 and C6 root stimulation. Although both C5 and C6 roots were innervated for deltoid and biceps brachii muscle in all subjects, the amplitude ratio of CMAPs (C5/C6) differed individually depending on the symptomatic intervertebral levels of the spinal cord. The C5 root predominantly innervated both deltoid and biceps brachii in patients with symptomatic cord lesions at the C4-C5 intervertebral level compared to patients with symptomatic cord lesions at the C5-C6 intervertebral level. Although no patients sustained postoperative radiculopathy in our study, severe weakness and unfavorable recovery are expected when the C5 root in patients with C4-C5 myelopathy is damaged. From the electrophysiological aspect, C4-C5 cord lesions are likely to be a potential risk factor for postoperative shoulder muscle weakness in patients with compressive cervical myelopathy.

Does cortical motor neuron excitability change in peripheral nerve injury?

OBJECTIVE: To investigate changes in cortical motor neuron excitability after peripheral nerve injury, evoked spinal cord potentials (ESCPs) following hemispheric transcranial magnetic stimulation (TMS) were recorded in awake patients with unilateral brachial plexus injury. METHODS: ESCPs following hemispheric TMS were recorded in 6 patients with unilateral complete type brachial plexus injury. Studies were performed within 6 months from the time of injury. ESCPs were recorded from posterior epidural space using catheter electrodes. Hemispheric TMS was applied on the motor cortex using a figure-of-8 coil. The threshold of ESCPs following hemispheric TMS was measured. The number, latency, and amplitude of ESCPs following high stimulus hemispheric TMS were measured and compared. RESULTS: No significant change was observed in the threshold of ESCPs following TMS contra-lateral to the injured upper limb compared to that following TMS contra-lateral to the intact upper limb. Several ESCP components were recorded following high stimulus hemispheric TMS. No significant changes were observed in comparison with number, latency and amplitude of ESCPs following high stimulus TMS contra-lateral to the injured upper limb and those following TMS contra-lateral to the intact upper limb. CONCLUSIONS: From a study of ESCPs following single TMS, no evidence was obtained that cortical motor neuron excitability changes in patients with traumatic unilateral brachial plexus injury at relatively early stages. We investigated the changes of cortical motor neuron excitability in patients with brachial plexus injury from the ESCPs following TMS. In single TMS, our data gave no evidence for cortical excitability changes at relatively early stages.