Spectral Analysis of Ultrasound Radiofrequency Backscatter for the Detection of Intercostal Blood Vessels.

Spectral analysis of ultrasound radiofrequency backscatter has the potential to identify intercostal blood vessels during ultrasound-guided placement of paravertebral nerve blocks and intercostal nerve blocks. Autoregressive models were used for spectral estimation, and bandwidth, autoregressive order and region-of-interest size were evaluated. Eight spectral parameters were calculated and used to create random forests. An autoregressive order of 10, bandwidth of 6 dB and region-of-interest size of 1.0 mm resulted in the minimum out-of-bag error. An additional random forest, using these chosen values, was created from 70% of the data and evaluated independently from the remaining 30% of data. The random forest achieved a predictive accuracy of 92% and Youden's index of 0.85. These results suggest that spectral analysis of ultrasound radiofrequency backscatter has the potential to identify intercostal blood vessels. (jokling@siue.edu) © 2018 World Federation for Ultrasound in Medicine and Biology.

Restoration of stepping-forward and ambulatory function in patients with paraplegia: rerouting of vascularized intercostal nerves to lumbar nerve roots using selected interfascicular anastomosis.

The objective of this study is to restore stepping-forward and ambulatory function in paraplegic patients with chronic injuries. Two to four normal vascularized intercostal nerves above the spinal cord injury site were obtained by cutting in the distal end at the midclavicular line. The proximal ends were disconnected from the levatores costarum. Nerves were then transferred to the vertebral canal through a submuscle tunnel and sutured with the selected fascicula of lumbar nerve roots (L 1/2 or L 3/4) by epiperineurial neurorrhaphy in the subdura or extradura. If the selected intercostal nerve was not of sufficient length to reach the specific lumbar region, a sural nerve segment was isolated, sheared into two segments, and attached to the intercostal nerve for grafting. Twenty-three patients, whose injury sites were between the thoracic T9 and T12 levels, were followed postoperatively for a period ranging from 2 to 11 (average: 3.5) years. Of these patients, 18 (78%) regained the stepping-forward function and were able to walk with crutches or other ambulatory assistive devices. In addition, 21 (91%) patients had improved thigh sensation. This intercostals nerve rerouting procedure restores significant stepping-forward and, in turn, ambulatory function and thigh muscle sensation in paraplegic patients.

Neuronal structure of microvascular transplants with and without neuronal anastomosis.

OBJECTIVE: Latissimus dorsi transplants have little neuronal regenerative capacity without neuronal anastomosis. Histologic differences between transplants with and without neuronal anastomosis and 2 distinct types of neurosurgical reanastomosis are highlighted in this study. PATIENTS AND METHODS: Fifty-four patients with squamous cell carcinomas of the oral cavity (T4) were treated by tumor resection and homolateral neck dissection. The defect was covered with a microvascular latissimus dorsi transplant. In 15 patients, no neuronal anastomoses were performed. In 21 patients, the thoracodorsal nerves were used for microneurosurgical reanastomosis, whereas in 18 patients, the cutaneous branches of the intercostal nerves were used for microneurosurgical reanastomosis. The transplant was examined during surgery and 9 months after surgery by means of a histologic examination of a biopsy specimen. The number of fascicles, the degree of fibrosis, and the myelination were examined. Furthermore, a neurosensory examination was performed 9 months after surgery. RESULTS: Overall, our patients had an average of 12.1 fascicles during surgery. After surgery, patients without neuronal anastomosis showed an average of 4.9 fascicles, patients with nerve anastomosis to the cutaneous branches of the intercostal nerve showed an average of 6.2 fascicles, and patients with anastomosis to the thoracodorsal nerve showed an average of 9.6 fascicles. In cases of nerve anastomosis, a lesser degree of fibrosis was found, together with good myelinization. The clinical examination showed the best neurosensory function in the transplants with anastomosis to the thoracodorsal nerve and the worst function in those without neuronal anastomosis. CONCLUSION: Neuronal reanastomosis led to more surviving neuronal structures in the postoperative histologic specimen. The highest density of fascicles was found in the well vascularized thoracodorsal nerve. The neurosensory function agrees with the histologic result.

Can vascularization improve the surgical outcome of the intercostal nerve transfer for traumatic brachial plexus palsy? A clinical comparison of vascularized and non-vascularized methods.

It is very difficult to design a well-controlled comparative study for clarifying the value of vascularized nerve grafting in clinical cases. In order to understand whether or not the vascularizing procedure has any clinical value in nerve transfer and in nerve grafting, we compared non-vascularized with vascularized intercostal nerve transfer in patients with brachial plexus injury. Factors that were likely to affect the results were controlled. We found there was no significant difference in the functional outcome and no difference in the regenerating rate of the nerves between nonvascularized and vascularized intercostal nerve transfer. We concluded that the vascularizing procedure had little clinical value not only in intercostal nerve transfer, but also in nerve grafting irrespective of the length of the gap, when the recipient bed had normal vascularity.

Total intercostal artery reimplantation for descending thoracic aortic replacement.

Reimplantation of all intercostal arteries was performed with a T-shaped graft for spinal cord protection in a 64-year-old man who required long-segment replacement of the descending thoracic aorta. The T-shaped graft maintained blood flow to the intercostal arteries, and no neurologic deficits developed.

Serratus anterior intercostal nerve graft: a new vascularized nerve graft.

We present our investigative and clinical experience with a new vascularized nerve graft: the serratus anterior intercostal nerve graft. The serratus branch of the thoracodorsal arterial system was injected with silicone rubber injection compound in seven fresh cadavers (N = 11 injected specimens) after the composite serratus-intercostal structures were harvested. Microdissection of selected vascular territories was then performed. Our findings reconfirmed the previously described vascular connections between the thoracodorsal system and the intercostal vessels via periosteal vessels. We also newly discovered vascular anastomoses between the serratus anterior muscle and the intercostal artery running within a mesentery. This mesentery is lateral to and distinct from the serratus-periosteal-intercostal network. The nerve graft was applied clinically in the reconstruction of a complex soft-tissue, 13-cm ulnar nerve defect of the volar forearm after an electrical injury. The clinical application was successful with limb salvage and return of protective sensation at 4 months. Our clinical and investigative results support the feasibility of the serratus anterior intercostal nerve graft, a unique and versatile new vascularized nerve graft.

[Vascularized intercostal nerve transfer--an experimental study].

The influence of vascularized intercostal nerve detachment on axonal regeneration and skeletal muscle recovery was examined in two experiments using two mongrel dogs. Experiment 1: The influence of detachment of the vascularized intercostal nerve on axonal regeneration and interfascicular blood flow was examined. Detachment of the intercostal nerve without accompanying blood vessels resulted in a marked decrease in blood flow and axonal degeneration at the distal 60% of the total length of the intercostal nerve. In contrast, no significant axonal degeneration was observed in the intercostal nerve that remained vascularized. Experiment 2: The condition of the biceps brachii muscles was continuously studied up to 9 months after intercostal nerve transfer. 1) Nine months after the intercostal nerve transfer, the regeneration of the biceps brachii as estimated by the wet weight was better at the vascularized side than at the unvascularized side. 2) Histochemical analysis on the biceps brachii revealed that type 1 fiber was predominant over type 2 fiber at six months post-transfer, whereas both type 1 and type 2 fiber were equally present at one month after transfer.

Intercostal blocks with etidocaine. Preliminary report.

Although the results are few and should be considered as preliminary, the following conclusions may be drawn: 1. Etidocaine 0.5% and bupivacaine 0.5%, both with adrenaline (5 mug/ml), are comparable with regard to duration of sensory block. 2. Etidocaine 0.5% without adrenaline did not give the same duration of complete sensory block as when adrenaline was present. 3. Etidocaine 0.5% acts as a vasodilator at the site of injection. Adrenaline added to the solution counteracts the dilating effect. 4. Blood level studies of etidocaine do not at present show differences when 0.5% solution with or without adrenaline is used.