Ultrasound-guided locoregional anaesthesia for carotid endarterectomy: a prospective observational study.

INTRODUCTION: Ultrasound guidance is increasingly used for invasive anaesthetic procedures to improve efficacy, facilitate performance and reduce risk of complications. Herein, we present a simple approach to ultrasound-guided locoregional anaesthesia for patients undergoing eversion carotid endarterectomy. METHODS: At the level of the base of the carotid bifurcation, the needle was inserted at the lateral border of the sternocleidomastoid muscle and, guided by ultrasound, advanced 0.5-1 cm posterolateral to the carotid artery, where ropivacaine (7.5 mg ml(-1)) was injected. During retraction of the needle, additional local anaesthetic was administered beneath the sternocleidomastoid muscle and, finally, subcutaneous infiltration along the surgical incision line was performed. The primary study end point was the amount of additional ropivacaine (7.5 mg ml(-1)) provided intra-operatively. Secondary measures included the occurrence of puncture-related complications and the adverse effects to locoregional anaesthesia. RESULTS: Sixty consecutive patients admitted for primary carotid endarterectomy were prospectively included. The volume of administered ropivacaine for locoregional anaesthesia and subsequent intra-operative supplementation was 31.7 ± 3.5 and 1.9 ± 2.5 ml, respectively. There were no conversions to general anaesthesia. Intravascular or subarachnoid injection of local anaesthetic did not occur, and symptoms of local anaesthetic systemic toxicity did not present. Related to the blockade, hoarseness (72%), Horner syndrome (37%), cough (20%), facial palsy (13%) and dysphagia (12%) were observed and resolved on the first postoperative day. CONCLUSIONS: This observational study demonstrates that the described ultrasound-guided locoregional anaesthesia is suitable for eversion carotid endarterectomy and the amount of supplemental anaesthetic during the surgery is low.

[Carotid-surgery in ultrasound-guided anesthesia of the regio colli lateralis]. / Ultraschallgestützte Blockade der Regio colli lateralis zur Karotis-Chirurgie -- eine Fallserie.

OBJECTIVE: Carotid endarterectomy significantly reduces the risk of stroke in patients with symptomatic and asymptomatic carotid artery stenosis. An increasing number of interventions in carotid surgery are performed under regional anesthesia in conscious patients. Carotid endarterectomy in local anesthesia requires block of the cervical nerves C2-C4, which may be accomplished in different ways. The most frequent method of regional anesthesia in carotid surgery is a combined block of profunda and superficial cervical plexus (by using a nerve stimulator). Ultrasound is frequently used in anesthesia for venous access and peripheral nerve block. By ultrasound, it is possible to visualize puncture needle and spread of local anesthetics at the correct position for block of cervical plexus in carotid surgery. The aim of the case reports was to demonstrate the effectiveness of using ultrasound for regional anesthesia in carotid surgery. METHOD: At the level of carotid bifurcation, scalene muscles were visualized by ultrasound (10-MHz-transducer). At this position, a puncture needle was inserted in the beam of ultrasound. Between the anterior scalene and the sternocleidomastoid muscles the local anesthetics were injected (10 ml prilocaine 1 %, 20 ropivacaine 0.375 %). In addition, superficial cervical plexus was performed by subcutaneous injection (10 ml prilocaine 1 %, 40 ropivacaine 0.375 %). Sedation was performed by application of remifentanil (max. 0.02 microg/kg/min), as needed. RESULTS: Ultrasound guided cervical block was performed in 29 patients. In all cases cervical plexus block was complete. A conversion to general anesthesia during operation was not necessary in any case. CONCLUSION: Ultrasound presents an alternative to cervical block using nerve stimulation, especially in patients with anatomical abnormalities. The method proves to be effective and may improve the approach to profundeal cervical plexus.

Monoamine storage sites in the rat superior cervical ganglion following synthesis inhibition.

Monoamine storage sites in paraganglionic (PG-) cells of the rat superior cervical ganglion were investigated by electron and fluorescence microscopy following treatment with p-chlorophenylalanine (pCPA), disulfiram or guanethidine respectively. Dense core vesicles in PG-cells are significantly decreased (p less than 0.001) in number following pCPA, and in the majority of these cells following disulfiram and guanethidine. However in a minor portion of PG-cells the latter agents cause an increase in number and in size of dense core vesicles, in parallel with structural alterations. In agreement with these electron microscopic findings fluorescence microscopic and cytophotometric evaluations reveal a general decrease in catecholamine content with few cells showing an increase. The findings provide a morphological basis for the assumption, that monoamine storage sites in PG-cells can be decreased by inhibition of monoamine synthesis, following administration of pCPA, disulfiram and guanethidine. However the two types of responses of PG-cells which occur after disulfiram and guanethidine demonstrate a functional heterogeneity of this cell system in the rat superior cervical ganglion which is discussed.

Detachment of structurally intact nerve endings from chromatolytic neurones of rat superior cervical ganglion during the depression of synaptic transmission induced by post-ganglionic axotomy.

1. Electrophysiological studies showed that injury of post-ganglionic nerve fibres leads to severe and prolonged depression of synaptic transmission through the rat superior cervical ganglion, beginning within 24 h. This is in line with the results of previous studies in other species and upon other neurones. 2. electron microscopy after post-ganglionic axotomy revealed nerve endings of presynaptic type with all the specialized membrane-related features of a synaptic zone, but which were not apposed to any post-synaptic nervous element. These umusual profiles were interpreted as detached presynaptic nerve endings. In normal and control ganglia, such profiles formed at most 0-5% of all vesicle-containing profiles of presynaptic type; in ganglia with all major post-ganglionic branches cut the proportion rose to approximately 7%, between 3 and 7 d post-operatively. Over this period, the mean incidence of chromatolytic neurones was 74-6%. 3. Concomitantly, the incidence of synapses within the ganglion fell by about 75%, reaching its lowest levels between 3 and 7 d post-operatively. There was strikingly little evidence of persistence of post-synaptic membrane specializations ('membrane thickenings') following detachment of synapses. 4. At longer survival intervals the incidence of synapses gradually increased, and that of detached nerve endings gradually decreased; recovery was well advanced by 42 d. 5. The fall in the incidence of synapses was closely paralleled by a fall in the incidence of desmosome-like attachments in the ganglion; the incidence of such attachments was found to be correlated to a significant degree with that of synapses. 6. It is concluded that most or all of the synapses upon sympathetic neurones become physically dissociated during the chromatolytic reaction of these neurones to axotomy. The failure to persist of ultrastructurally specialized post-synaptic sites, and the loss of desmosomes (particularly marked for those involving purely post-ganglionic nervous elements) suggest that the post-ganglionic neurone is losing all its specializations for attachment. 7. Some evidence suggests that the satellite cells may effect the final separation between pre- and post-synaptic structures.

Schwann cell internuclear distances in developing rat unmyelinated nerve fibers.

The interrelation of Schwann cells in developing rat cervical sympathetic trunk was studied by measuring distances between consecutive Schwann cell nuclei in teased unmyelinated nerve fiber bundles (Remak fibers). From 300 to 400 inter-nuclear Schwann cell distances (INDs) were measured at ten days and 2, 4, 5, 6, 8, 12, and 16 weeks after birth. Median INDs increased from 54mum at ten days to reach adult values (90mum to 100mum) at 16 weeks of age. Mean axonal diameters measured in the contralateral cervical sympathetic trunk increased from 0.57mum to 0.69mum during the same period. Developmental changes in median INDs of Schwann cells correlated significantly with age but did not parallel increases in axonal diameter.

The fine structure of the cervical spinal cord, ventral root and brachial nerves in the wobbler (wr) mouse.

Much indirect evidence supports the prevailing concept that the wobbler mouse represents an inherited form of lower motor neuron degeneration, with resultant neurogenic muscular atrophy, due to an autosomal recessive gene (wr). This report, which emphasizes the fine structural changes in the wobbler mouse cervical spinal cord, ventral root and brachial nerves, both extends and modifies previously published data concerning the ultrastructural changes in this disorder. In addition to the more obvious neuronal cytoplasmic vacuolization known to occur, studies extended to a broader age range of wobbler mice have revealed neuronal alterations such as nonvacuolar dissolution of granular endoplasmic reticulum, proliferation of cytoplasmic microtubules and neurofilaments, proliferation of branched tubules resembling smooth endoplasmic reticulum, development of lipid droplets, and increased numbers of pleomorphic dense and lamellar cytoplasmic bodies. The spectrum of pathological changes in this murine form of motor neuron disease thus appears more complex and varied than has hitherto been appreciated, and may be relevant to the formulation of pathogenetic hypotheses.