Muhammad A. Munir

Decreasing sympathetic sprouting in pathologic sensory ganglia: a new mechanism for treating neuropathic pain using lidocaine

&NA; Lidocaine brings relief to those suffering from certain neuropathic pain syndromes in humans and in animal models. Evidence suggests that some neuropathic pain behaviors are closely associated with extensive sprouting of noradrenergic sympathetic fibers in the dorsal root ganglia (DRG). Using immunohistochemistry, we examined lidocaines effects on abnormal sprouting of sympathetic fibers in two animal models: rats with unilateral spinal nerve ligation (SNL) and rats with complete sciatic nerve transection (CSNT). For the first time, we have demonstrated that systemic lidocaine beginning at the time of surgery via an implanted osmotic pump remarkably reduces sympathetic sprouting (2–3 fold) (e.g. the density of sympathetic fibers and the number of DRG neurons surrounded by sympathetic fibers) in axotomized DRGs in SNL rats. The effects of systemic lidocaine lasted more than 7 days after the termination of lidocaine administration. Similar results were obtained after topical application of lidocaine to the nerve trunk to block abnormal discharges originating in the neuroma in CSNT rats. Results strongly suggest that sympathetic sprouting in pathologic DRG may be associated with abnormal spontaneous activity originating in the DRG or the injured axons (e.g. neuroma). This finding provides new insight into the mechanisms underlying sympathetic sprouting and increases our current understanding of the prolonged therapeutic effects of lidocaine on neuropathic pain syndromes.

A modified needle-inside-needle technique for the ganglion impar block.

PurposeThe ganglion impar is the fused terminus of the paired sympathetic chain located at the level of the sacrococcygeal junction. It has been blocked using a bent and a curved spinal needle via the anococcygeal ligament. It has also been approached through the sacrococcygeal disc using a straight spinal needle. We describe a neede-inside-needle modification of the latter approach.Technical featuresA 22-gauge (G), 1 1-inch (38 mm) needle is introduced through the sacrococcygeal ligament under fluoroscopy via the sacrococcygeal disc. A 25-G, 2-inch (50 mm) needle is introduced through the 22-G needle. Placement is confirmed with injection of iopamidol 300, 0.2 mL in the retroperitoneal space with the comma sign.ConclusionsThe bent and curved needle techniques are associated with significant discomfort, tissue trauma and risk of rectal perforation due to difficulty in obtaining a midline needle tip position. The straight spinal needle approach minimizes these problems, however there is increased risk of discitis and a longer spinal needle may help also raise incidence of needle breakage. The needleinside-needle technique may reduce these risks.RésuméObjectifLe ganglion coccygien est l’extrémité fusionnée de la chaîne sympathique pairée localisée à la jonction sacro-coccygienne. On a déjà utilisé une aiguille coudée ou courbée pour réaliser le bloc de ce ganglion en passant par le ligament ano-coccygien. On a aussi utilisé une aiguille rachidienne droite pour traverser le disque sacro-coccygien. Nous décrivons une modification «aiguille dans une aiguille» de cette dernière approche.Caractéristiques techniquesSous fuoroscopie, une aiguille de calibre 22 et de 38 mm est introduite dans le ligament sacro-coccy-gien en passant par le disque sacro-coccygien. Une aiguille de calibre 25, de 50 mm, est introduite dans l’aiguille 22. La mise en place est confrmée par le signe de la virgule avec l’injection de 300 mL d’iopamidol à 2 % dans l’espace rétropéritonéal.ConclusionL’utilisation d’une aiguille coudée ou courbée est associée à un inconfort important, un traumatisme tissulaire et un risque de perforation rectale dû à la difficulté d’obtenir une position médiane de la pointe de l’aiguille. L’aiguille rachidienne droite réduit ces problèmes, mais augmente le risque de discite; une aiguille rachidienne plus longue peut aussi élever l’incidence de cassure de l’aiguille. La technique «d’une aiguille dans une aiguille» peut réduire ces risques.

Are diagnostic lumbar facet injections influenced by pain of muscular origin

Introduction:  Nonradicular low back pain can be a difficult entity to accurately diagnose and treat. Facet joints, muscle, ligaments, and fascia have all been reported to be etiologies of acute and chronic low back pain. However, the facet joint as a source of low back pain is controversial. The diagnosis of facet joint pain is made by diagnostic facet joint or median nerve branch injections with a local anesthetic. The purpose of this study was to determine if the results of diagnostic facet joint injections are influenced by the technique used to perform these injections.

An in situ technique to retrieve an entrapped j-tip guidewire from an inferior vena cava filter.

IMPLICATIONS Entrapment of a guidewire in the vena cava filter during central venous catheter placement is a newly recognized complication. Complex techniques have been described to free the guidewire. We describe a simple in situ technique that may free the guidewire without the application of complex techniques.

Reduced duration of muscle relaxation with rocuronium in a normocalcemic hyperparathyroid patient

PurposeTo report a case of reduced duration of action of rocuronium in a patient with normocalcemic hyperparathyroid ism (HPT).Clinical featuresA 56-yr-old patient with primary HPT, who had had surgical resection of three and a half parathyroid glands nine months previously, was referred to our institution for further investigation of a persistent increase in parathyroid hormone. Preoperatively, the patient had a normal serum ionized and total calcium. The patient was diagnosed with a persistent parathyroid adenoma and was scheduled for an elective parathyroidectomy.General anesthesia was induced with iv propofol, fentanyl and succinylcholine. Intraoperatively, anesthesia was maintained with nitrous oxide in oxygen, and isoflurane. Neuromuscular blockade was attained using incremental doses of rocuronium. The average duration of 0.15 mg·kg−1 incremental doses of rocuronium was 5.9 min (expected: 13–18 min), and that of 0.2 mg·kg−1 was ten minutes (expected: 19–23 min).ConclusionPrimary HPT even in the absence of hypercalcemia may result in resistance to competitive blockade by rocuronium. It suggests that primary HPT may cause acetylcholine receptor upregulation resulting in hyposensitivity to non-depolarizing muscle relaxants.RésuméObjectifPrésenter un cas de réduction du temps d’action du rocuronium chez un patient atteint d’hyperparathyroïdie (HPT) normocalcémique.Éléments cliniquesUn patient de 56 ans, atteint d’HPT primaire, avait subi, neuf mois auparavant, la résection chirurgicale de trois glandes parathyroïdes et demie et avait été dirigé vers notre institution pour une investigation plus poussée de l’augmentation persistante de l’hormone parathyroïde. Avant l’opération, le patient avait un niveau de calcium total et ionisé normal. Le diagnostic d’adénome parathyroïde persistant a été établi et une parathyroïdectomie a été planifiée. L’anesthésie générale a été induite avec des agents iv, propofol, fentanyl et succinylcholine. Pendant l’opération, l’anesthésie a été maintenue avec du protoxyde d’azote dans de l’oxygène, et de l’isoflurane. Le blocage neuromusculaire a été obtenu par des doses progressives de rocuronium. La durée moyenne des doses progressives de 0,15 mg·kg−1 a été de 5,9 min (normale : 13–18 min), et celle des doses de 0,2 mg·kg−1 a été de 10 min (normale : 19–23 min).ConclusionL’HPT primaire, même sans hypercalcémie, peut provoquer une résistance au blocage compétitif du rocuronium. Ce qui suggère que l’HPT primaire puisse causer une régulation positive du récepteur d’acétylcholine menant à une hyposensibilité aux myorelaxants non dépolarisants.