nerve blocks in the diagnosis and therapy of visceral disease

Transcription

1 Visceral Pain nerve blocks in the diagnosis and therapy of visceral disease Guy Hans, MD, PhD Dept. of Anesthesiology, Multidisciplinary Pain Center Visceral Pain? Type of nociceptive pain (although often mixed!) Pain arising from the viscera: Pain originating in an organ or hollow structure re e.g. stomach, gall bladder but not only abdominal Compared to the skin, density of nociceptive fibres very hard to localise, or may even be felt as referred pain Visceral pain may be described as gnawing or aching, possibly associated with feelings of nausea Not to be confused with parietal pain segmental nerve roots innervating the peritoneum 1

2 Visceral pain: specific anatomic features Sympathetic nerves Parasympathetic nerves Sensory nerves Visceral Pain: indications for nerve blocks Afferent nociceptive fibers from the viscera accompany sympathetic (and parasympathetic) nerves Sympathetic blocks interrupt these pathways But also the efferent viscero-visceral pathways Relief of ischaemia and spasm Clinical situations in which blocks can be considered: Abdominal cancer Chronic non-malignant pain Acute abdominal pain Cardiac pain Perioperative purposes (Neuropathic pain) 2 helsenet.info

3 Clinical indications (1) Diagnostic Define the precise source of pain Distinguish local from referred (visceral) pain, from somatic pain (abdominal wall) Distinguish peripheral pain from central pain To dermine if pain is maintained by sympathetic nervous system Assessment of contribution of pain to immobility or muscle spasm Clinical indications (2) Prognostic Assess benefits/risks of neurolytic or neurodestructive ti blocks Guidance as to whether pharmacotherapy, definitive neurolytic blocks or surgical management should be considered Therapeutic Provide prompt and effective analgesia Pre or post injury! Allow adequate examination, intervention or mobilisation of the injured area 3 helsenet.info

4 Full understanding of relevant anatomy, pathophysiology of underlying Requirements for sympathetic blocks condition and technical skills Proper patient selection Resuscitation equipment Secure venous access essential Sedation? Constant monitoring (blood pressure, pulse oximetry) Radiological control (+ contrast) Aseptic technique essential Informed consent? Thoracic sympathetic ganglion block Upper thoracic sympathetic ganglia Resting against the heads of the ribs Covered by the pleura Lower ganglia are on the side of the vertebral bodies Sympathetic trunk runs between the ganglia Just in front of the somatic nerves useful in evaluation and management of Sympathetically maintained pain of upper thorax and chest wall, thoracic and upper abdominal viscera Intractable cardiac and abdominal angina helsenet.info 4

5 Thoracic sympathetic ganglion block (2) Needle 4-5cm lateral to spinous process Midway between transverse processess Directed to side of vertebral body Checked in lateral view Needle cephalad to vertebral foramen Advanced d until tip beside vertebral body, anterior to vertebral foramen and next to anterior aspect of the neck of the rib Splanchnic nerves block Greater, lesser and least splanchnic nerves provide the major preganglion contribution to the celiac plexus Cross lateral side of body of T12 Penetrate diaphragm Pleura lies lateral Crura of the diaphragm anterior More selective analgesia Higher risk of complications! 5 helsenet.info

6 Lateral end of transverse process of L1 Needle (tunnel vision) to pass beneath 12 th rib on to the side of body of T11 or T12 Medial placement against body! Needle tip between middle and anterior 1/3 of vertebral body Injection of contrast 5ml volume injected (LA ± phenol) Radiofrequency: Impedance < 250 Ohm Stimulation 50Hz with paresthesia <1 Volt Stimulation 2Hz (intercostal motoric act.) 3 lesions at 80 C during 90 seconds Turn needle cranially, neutral and caudally Celiac plexus block 3 splanchnic nerves synapse at the celiac ganglia 1 to 5 with diameter from 0.5 to 4.5cm Anterior and anterolateral to the aorta (L1) Left more inferior than right-sided ganglia Ganglia and preganglionic and postganglionic fibers constitue the celiac plexus Preganglionic splanchnic nerves, vagal preganglionic parasympathetic fibers, sensory fibers from the phrenic nerve, and postganglionic g sympathetic fibers Upper abdominal pain also for distal third of esophagus to transverse colon, liver and biliary tract, the adrenals and mesentery 6

7 Transverse process of L1 is identified Needle is laterally placed and oriented 45 toward the midline and about 15 cephalad Contact t with L1 vertebral body Upon bony contact, redirect less mesiad, so to walk off lateral surface of L1 vertebral body Tip of the needle Posterior to aorta on the left Anterolateral aspect of aorta on the right Radiofrequency has been described Superior hypogastric plexus block (presacral nerve) Retroperitoneal structure located bilaterally at lower 1/3 of L5 Confluence of lumbar sympathetic chains and branches of the aortic plexus + parasympathetic fibers originating in ventral roots of S2-4 Malignant pain of GI tract from the descending colon, sigmoid, to rectum, as well as urogenital system vaginal fundus, bladder, prostate, prostatic urethra, testes, seminal vesicles, uterus and ovaries No evidence for non-malignant pelvic pain Adhesions, endometriosis, pelvic inflammatory diseases 7

8 Identify L4-L5 interspace Needle entry point 5-7 cm lateral to midline at this level (scopy!) Insert 25G needle and direct to lie anterolateral to L5/S1 interspace Aspiration of blood possible advance further 8 10ml volume injected Neurolytics or RF Be careful for complications! Ganglion impar (ganglion of Walther) Solitary retroperitoneal structure, located at the level of the sacrococcygeal junction Marks termination of paired paravertebral sympathetic chains Pain involving perineum, distal rectum and anus, distal urethra, vulva and distal third of vagina 8

9 Fluoroscopy: lateral fluoro view visualize the sacrococcygeal junction 20 or 22-gauge needle advanced through the sacrococcygeal ligament until needle tip is just barely anterior to the sacrum Contrast is then injected to visualize correct spread/placement. Finally, a local anesthetic (and sometimes corticosteroid ± clonidine) is injected RF reported, but uncertain results Pundendal nerve block A somatic nerve which is a large branch of the sacral plexus (L4-5, S1-4) innervates the external genitalia, and sphincters for bladder and rectum originating in Onuf's nucleus in the sacral region of the spinal cord Childbirth or bicycling can compress or stretch the pudendal nerve, causing temporary/permanent loss of function Entrapment of the nerve is very rare but can happen Tumor invasion can destroy nerve 9

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