Mahmood Ahmad

Preemptive analgesia I: physiological pathways and pharmacological modalities

PurposeThis two-part review summarizes the current knowledge of physiological mechanisms, pharmacological modalities and controversial issues surrounding preemptive analgesia.SourceArticles from 1966 to present were obtained from the MEDLINE databases. Search terms included: analgesia, preemptive; neurotransmitters; pain, postoperative; hyperalgesia; sensitization, central nervous system; pathways, nociception; anesthetic techniques; analgesics, agents.Principal findingsThe physiological basis of preemptive analgesia is complex and involves modification of the pain pathways. The pharmacological modalities available may modify the physiological responses at various levels. Effective preemptive analgesic techniques require multi-modal interception of nociceptive input, increasing threshold for nociception, and blocking or decreasing nociceptor receptor activation. Although the literature is controversial regarding the effectiveness of preemptive analgesia, some general recommendations can be helpful in guiding clinical care. Regional anesthesia induced prior to surgical trauma and continued well into the postoperative period is effective in attenuating peripheral and central sensitization. Pharmacologic agents such as NSAIDs (non-steroidal anti-inflammatory drugs) opioids, and NMDA (N-methyl-D-aspartate)- and alpha-2-receptor antagonists, especially when used in combination, act synergistically to decrease postoperative pain.ConclusionThe variable patient characteristics and timing of preemptive analgesia in relation to surgical noxious input requires individualization of the technique(s) chosen. Multi-modal analgesic techniques appear most effective.RésuméObjectifLa présente revue, en deux parties, résume les connaissances actuelles sur les mécanismes physiologiques et les modalités pharmacologiques de l’analgésie préventive ainsi que sur les questions controversées qui l’entourent.SourcesDes articles, de 1966 à aujourd’hui, obtenus à partir des bases de données MEDLINE. Les termes de la recherche comprennent: analgesia, preemptive; neurotransmitters; pain, postoperative; hyperalgesia; sensitization, central nervous system; pathways, nociception; anesthetic techniques; analgesics, agents.Constatations principalesLes fondements physiologiques de l’analgésie préventive sont complexes et impliquent une modification des mécanismes de la douleur. Les modalités pharmacologiques disponibles peuvent modifier les réponses physiologiques à différents niveaux. Les techniques efficaces d’analgésie préventive exigent l’interception multimodale du stimulus nociceptif la hausse du seuil de nociception et le blocage ou la baisse de l’activation des récepteurs de nociception. Même si la documentation est controversée concernant l’efficacité de l’analgésie préventive, certaines recommandations générales peuvent guider les soins cliniques. Lanesthésie régionale induite avant le trauma chirurgical et poursuivie après l’opération est efficace pour diminuer la sensibilisation centrale et périphérique. Les agents pharmacologiques comme les AINS (anti-inflammatoires non stéroïdiens), les opioïdes et les antagonistes des récepteurs alpha-2 et NMDA (N-méthyl-D-aspartate), surtout lorsqu’ils sont combinés, agissent en synergie pour réduire la douleur postopératoire.ConclusionLa diversité des patients et le moment choisi pour administrer l’analgésie préventive en relation avec le stimulus chirurgical nocif demandent l’individualisation de la, ou des, technique choisie. Des techniques analgésiques multimodales semblent plus efficaces.

The efficacy of lumbar epidural steroid injections in patients with lumbar disc herniations.

INTRODUCTION: Lumbar epidural steroid injection can be accomplished by one of three methods: caudal (C), interlaminar (IL), or transforaminal (TF). In this study we sought to determine the efficacy of these techniques for the management of radicular pain associated with lumbar disk herniations. METHODS: Ninety patients aged 18–60 years with L5-S1 disk herniations and radicular pain were randomly assigned to one of these groups to have epidural steroid injection therapy every 2 wk for a maximum of three injections. Pain relief, disability, and activity levels were assessed. RESULTS: Pain relief was significantly more effective with TF injections. At 24 wk from the initiation of this study, pain relief was as follows: C: complete pain relief: 1/30, partial pain relief: 16/30, and no relief: 13/30; IL: complete pain relief: 3/30, partial pain relief: 15/30, and no relief: 12/30; and TF: complete pain relief: 9/30, partial pain relief: 16/30, and no relief: 5/30. CONCLUSIONS: The TF route of epidural steroid placement is more effective than the C or IL routes. We attribute this observation to a higher incidence of steroid placement in the ventral epidural space when the TF method is used.

PREEMPTIVE ANALGESIA II: RECENT ADVANCES AND CURRENT TRENDS

PurposeThis two-part review summarizes the current knowledge of physiological mechanisms, pharmacological modalities and controversial issues surrounding preemptive analgesia.SourceArticles from 1966 to present were obtained from the MEDLINE databases. Search terms included analgesia, preemptive; neurotransmitters; pain, postoperative; hyperalgesia; sensitization, central nervous system; pathways, nociception; anesthetic techniques; analgesics, agents.Principal findingsIn Part I of this review article, techniques and agents that attenuate or prevent central and peripheral sensitization were reviewed. In Part II, the conditions required for effective preemptive techniques are evaluated. Specifically, preemptive analgesia may be defined as an antinociceptive treatment that prevents establishment of altered central processing of afferent input from sites of injury. The most important conditions for establishment of effective preemptive analgesia are the establishment of an effective level of antinociception before injury, and the continuation of this effective analgesic level well into the post-injury period to prevent central sensitization during the inflammatory phase. Although single-agent therapy may attenuate the central nociceptive processing, multimodal therapy is more effective, and may be associated with fewer side effects compared with the high-dose, single-agent therapy.ConclusionThe variable patient characteristics and timing of preemptive analgesia in relation to surgical noxious input require individualization of the technique(s) chosen. Multi-modal analgesic techniques appear more effective.RésuméObjectifLa présente revue, en deux parties, résume les connaissances actuelles sur les mécanismes physiologiques et les modalités pharmacologiques de l’analgésie préventive ainsi que sur les questions controversées qui l’entourent.SourceDes articles, de 1966 à aujourd’hui, obtenus à partir des bases de données MEDLINE. Les termes de la recherche comprennent: analgesia, preemptive; neurotransmitters; pain, postoperative; hyperalgesia; sensitization, central nervous system; pathways, nociception; anesthetic techniques; analgesics, agents.Constatations principalesDans la Partie I de cet exposé de synthèse, les techniques et les médicaments qui atténuent ou préviennent la sensibilisation centrale et périphérique ont été réexaminés. Dans la Partie II, les conditions nécessaires à l’efficacité des techniques préventives sont évaluées. Plus précisément, on peut définir l’analgésie préventive comme un traitement antinociceptif qui prévient la transmission centrale altérée du stimulus afférent provenant des sites de lésion. Les conditions les plus importantes de son efficacité sont l’établissement d’un niveau suffisant d’antinociception avant la lésion et l’entretien de ce niveau d’analgésie efficace après la lésion afin d’empêcher la sensibilisation centrale pendant la phase inflammatoire. Même si le traitement avec un médicament unique peut diminuer la sensibilisation nociceptive centrale, le traitement multimodal est plus efficace et peut comporter moins d’effets secondaires comparativement à la forte dose d’un médicament unique.ConclusionLa diversité des patients et le moment choisi pour administrer l’analgésie préventive en relation avec le stimulus chirurgical nocif exigent une individualisation des techniques choisies. Des techniques analgésiques multimodales semblent plus efficaces.

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.

Pain relief with intraarticular or medial branch nerve blocks in patients with positive lumbar facet joint SPECT imaging: a 12-week outcome study.

Background: Single-photon emission computed tomography (SPECT) is useful in identifying patients who may respond to lumbar facet injections. There are two methods for performing lumbar facet joint injections: intraarticular and medial branch nerve blocks. A consensus has yet to be reached among physicians as to which method is the most effective. The purpose of this study was to compare the effectiveness of intraarticular and medial branch nerve blocks in SPECT-positive lumbar facet joint patients with nonradicular lower back pain. Method: This study was a prospective, double-blinded outcome study of 12 weeks’ duration. Forty-six male (26) and female patients (20) between the ages of 18 and 55 (mean 39.3 years) with nonradicular lower back pain who were lumbar facet joint SPECT-positive were studied. No patient was included in this study if magnetic resonance imaging evidence of a lumbar disc herniation was present. Patients were randomly assigned by computer to have intraarticular (group I) or medial branch nerve blocks (group II) with lidocaine and triamcinolone, with 23 patients in each group. Outcome measurements assessed the Numeric Pain Intensity Scores (NPIS 0–10) and the Oswestry Disability Index scores (ODI 0–50). Results: There were no differences in demographics between the two groups. The percentage of pain relief (61%) and the percentage of disability (53%) reduction were significantly greater (P <0.05) in group I when compared to group II (26% and 31% respectively). Conclusions: Intraarticular lumbar facet joint injections are more effective than medial branch nerve blocks in SPECT-positive patients.

Recurrent Postoperative CRPS I in Patients With Abnormal Preoperative Sympathetic Function

PURPOSE A complex regional pain syndrome of an extremity that has previously resolved can recur after repeat surgery at the same anatomic site. Complex regional pain syndrome is described as a disease of the autonomic nervous system. The purpose of this study was to evaluate preoperative and postoperative sympathetic function and the recurrence of complex regional pain syndrome type I (CRPS I) in patients after repeat carpal tunnel surgery. METHODS Thirty-four patients who developed CRPS I after initial carpal tunnel releases and required repeat open carpal tunnel surgeries were studied. Laser Doppler imaging (LDI) was used to assess preoperative sympathetic function 5-7 days prior to surgery and to assess postoperative sympathetic function 19-22 days after surgery or 20-22 days after resolution of the CRPS I. Sympathetic nervous system function was prospectively examined by testing reflex-evoked vasoconstrictor responses to sympathetic stimuli recorded with LDI of both hands. Patients were assigned to 1 of 2 groups based on LDI responses to sympathetic provocation. Group I (11 of 34) patients had abnormal preoperative LDI studies in the hands that had prior surgeries, whereas group II (23 of 34) patients had normal LDI studies. Each patient in this study had open repeat carpal tunnel surgery. RESULTS In group I, 8 of 11 patients had recurrent CRPS I, whereas in group II, 3 of 23 patients had recurrent CRPS I. All of the recurrent CRPS I patients were successfully treated with sympathetic blockade, occupational therapy, and pharmacologic modalities. Repeat LDI after recurrent CRPS I resolution was abnormal in 8 of 8 group I patients and in 1 of 3 group II patients. CONCLUSIONS CRPS I can recur after repeat hand surgery. Our study results may, however, identify those individuals who may readily benefit from perioperative therapies. TYPE OF STUDY/LEVEL OF EVIDENCE Prognostic I.

Pain medicine and the injectionist: we need to preserve our specialty.

Ten days later, the patient presented himself in the emergency department. He complained of severe, progressive headache independent of position and had a temperature of 39.0°C, nuchal rigidity, and a positive Brudzinski’s sign. Although the immediate cerebrospinal fluid (CSF) culture revealed no bacteria, the CSF analysis indicated bacterial meningitis. Intravenous ceftriaxone, vancomycin, rifampicin, and dexamethasone were started, and the patient was admitted to the hospital. Two days later, the patient’s temperature had normalized, and clinical progression was favorable. On postoperative day 14, Streptococcus sanguis was isolated in the CSF cultures. The diagnosis of primary bacterial meningitis was made, and the former antibiotic regime was changed to 6 million units of penicillin. The patient was discharged home on postoperative day 18. One month after discharge, the patient worked half days, partly because of difficulty of concentration. Bacterial meningitis after spinal anesthesia is a very rare but serious complication. The incidence of postspinal bacterial meningitis is less than 4.5 per 100,000.1 Three explanations are possible for CSF infection after spinal anesthesia: (1) break in sterile technique with direct introduction of bacteria, (2) hematogenic spread, and, even less likely, (3) primary contamination of equipment and anesthetic drug. A causal relationship between dural puncture and meningitis should not be assumed for all cases, because coincident meningitis has been reported after general anesthesia and even after cancellation of anesthesia and surgery.2 The onset of postspinal meningitis can be delayed up to 30 days if patients are treated with antibiotics perioperatively.3 As in a delayed-onset meningitis case reported by Ezri et al.,4 our patient did not receive any perioperative antibiotics. Why the onset of meningitis was delayed is not clear. Coincident meningitis unrelated to the lumbar puncture cannot be excluded. However, a delayed infection by Streptococcus viridans, in which the patient did not have dental or respiratory tract problems perioperatively and all blood cultures were negative, is very rare. We conclude that bacterial meningitis may occur after spinal anesthesia even when all precautions have been taken and apparent risk factors are absent. Even 10 days after performing a spinal puncture, one should be alert for symptoms of meningitis.