Two patients underwent thoracotomy for resection of pulmonary or esophageal carcinoma. Postoperatively, epidural catheters were inserted for pain management. Complaints of severe injection pain over the abdomen or lower extremities were made during one administration of pain medication. Progressive weakness and numbness developed over the lower trunk and lower extremities, with subsequent respiratory difficulties. Potassium chloride (KCl) was suspected to have been mistaken for normal saline as the diluent for morphine. In addition to endotracheal intubation and ventilatory support, steroids were administered both intravenously and epidurally to suppress spinal cord irritation. The two patients regained motor and sensory functions 14 and 18 hours later, respectively, without sequelae.

Report of two cases

Phantom limbs and the concept of a neuromatrix

SUMMARY
Lumbar epidural blockade has been used in a series of 659 patients to compare the analgesic properties of lidocaine and prilocaine.

Solutions of both compounds were compared as hydrochloride salts in 2% and 3% concentration with and without adrenaline 1:200,000. Solutions of base, made soluble by equilibration with carbon dioxide at a pC02 of 700 mm Hg were also compared in concentrations of 1.75% for lidocaine and 1.71% for prilocaine.

Comparisons were based on measurements of latency, spread of analgesia, intensity of motor blockade and duration of analgesia.

The quality of blockade in all the test solutions was increased by the addition of 1:200,000 adrenaline. Prilocaine has a slow latency compared with lidocaine, but in plain solution its duration is longer than that of lidocaine.

The 3% hydrochloride solutions have no practical advantage over die 2% solutions for epidural blockade.

Analgesia resulting from the C02-base solutions is superior in every respect to the blockade produced by equivalent concentrations of the hydrochloride salts.

A Comparison of the Hydrochloride and Carbon Dioxide Salts of Lidocaine and Prilocaine in Epidural Analgesia

Background: The evidence-based practice guidelines for the management of chronic spinal pain with interventional techniques were developed to provide recommendations to clinicians in the United States. Objective: To develop evidence-based clinical practice guidelines for interventional techniques in the diagnosis and treatment of chronic spinal pain, utilizing all types of evidence and to apply an evidence-based approach, with broad representation by specialists from academic and clinical practices. Design: Study design consisted of formulation of essentials of guidelines and a series of potential evidence linkages representing conclusions and statements about relationships between clinical interventions and outcomes. Methods: The elements of the guideline preparation process included literature searches, literature synthesis, systematic review, consensus evaluation, open forum presentation, and blinded peer review. Methodologic quality evaluation criteria utilized included the Agency for Healthcare Research and Quality (AHRQ) criteria, Quality Assessment of Diagnostic Accuracy Studies (QUADAS) criteria, and Cochrane review criteria. The designation of levels of evidence was from Level I (conclusive), Level II (strong), Level III (moderate), Level IV (limited), to Level V (indeterminate). Results: Among the diagnostic interventions, the accuracy of facet joint nerve blocks is strong in the diagnosis of lumbar and cervical facet joint pain, whereas, it is moderate in the diagnosis of thoracic facet joint pain. The evidence is strong for lumbar discography, whereas, the evidence is limited for cervical and thoracic discography. The evidence for transforaminal epidural injections or selective nerve root blocks in the preoperative evaluation of patients with negative or inconclusive imaging studies is moderate. The evidence for diagnostic sacroiliac joint injections is moderate. The evidence for therapeutic lumbar intraarticular facet injections is moderate for short-term and long-term improvement, whereas, it is limited for cervical facet joint injections. The evidence for lumbar and cervical medial branch blocks is moderate. The evidence for medial branch neurotomy is moderate. The evidence for caudal epidural steroid injections is strong for short-term relief and moderate for long-term relief in managing chronic low back and radicular pain, and limited in managing pain of postlumbar laminectomy syndrome. The evidence for interlaminar epidural steroid injections is strong for short-term relief and limited for long-term relief in managing lumbar radiculopathy, whereas, for cervical radiculopathy the evidence is moderate. The evidence for transforaminal epidural steroid injections is strong for short-term and moderate for long-term improvement in managing lumbar nerve root pain, whereas, it is moderate for cervical nerve root pain and limited in managing pain secondary to lumbar post laminectomy syndrome and spinal stenosis.

Interventional Techniques: Evidence-based Practice Guidelines in the Management of Chronic Spinal Pain

Spinal opiate analgesia: characteristics and principles of action.

Lignocaine has been widely used for conduction and topical analgesia since 1948 and more recently for general analgesia1 2. Although arbitrary limits have been set to safe clinical dosage, these have been determined mainly by animal experimentation. Little information is available about absolute toxic thresholds in man, or about rates of absorption from any of the common sites of administration. Moreover, the successful use of lignocaine as a systemic analgesic has led to the suspicion that some of its apparent effectiveness in conduction analgesia may be explained by a general analgesic action after absorption into the blood stream. Theacute toxicity of lignocaine has been studied in man by Steinhaus and Howland3, and Kimmey and Steinhaus4, using the drug intravenously as an adjuvant to thiopentone and nitrous oxide anzsthesia. However, blood concentrations of lignocaine were not estimated in these patients and so these series provided no information regarding thresholds of toxicity. Foldes and his colleagues examined the acute toxicity of lignocaine in conscious human volunteers and measured the concentration of lignocaine in the blood when objective signs of overdosage occurred5. These workers used intravenous infusion rates of O.Smg/kg bodyweight per minute and they found that subjective signs of toxicity occurred after 1.5mg/kg body weight had been given. Objective signs

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2044.1961.tb13426.x

Concentrations of lignocaine in the blood after intravenous, intramuscular epidural and endotracheal administration

A number of variables determine how far neural blockade will spread after injection of an analgesic solution into the epidural space. Some of these are intrinsic to the patient, and some are extrinsic, depending on variations of technique and the drugs employed. The intrinsic variables governing the spread of solutions in the epidural space are best understood if we consider the space as a more or less cylindrical reservoir, the volume of the reservoir being determined by such factors as the length and breadth of the cylinder, and the size of the structures normally contained in it. Draining the reservoir are certain conduits and escape routes, through which seepage and absorption of injected materials can take place. The rate of disappearance of solutions from the area will depend on the patency and efficiency of the escape routes. The most notable of these are the intervertebral foramina and the extradural venous plexuses, and any study of the spread of analgesic solutions must take account of the factors which affect these structures, for the extent of neural blockade will be governed in part by the speed at which nerves are blocked, in relation to the rate with which the analgesic solution is removed from their vicinity. If the speed of the latter is fast compared to the former, solutions may be removed so rapidly that there is no chance for them to spread and produce widespread blockade. Whereas if absorption is slow there will be an opportunity for more prolonged and intimate contact between solution and nerves, so that the extent and intensity of spread is likely to be greater.

Spread of analgesic solutions in the epidural space and their site of action: a statistical study

https://rapm.bmj.com/content/rapm/23/1/104.full.pdf

Paraplegia following intracord injection during attempted epidural anesthesia under general anesthesia

SUMMARY Varying concentrations of lignocaine between 1 and 5 per cent with and without adrenaline 1/200,000 were used for epidural analgesia in 255 patients. Measurements were made of latency of onset, degree of segmental spread, intensity of motor blockade and duration. The segmental spread of analgesia depended on the mass of solute injected and not on the volume, and at any given age the relationship between dose and area of segmental blockade was constant for all concentrations between 2 per cent and 5 per cent. Lignocaine in 1 per cent concentration blocked more spinal segments than the stronger concentrations, but produced a blockade of weaker intensity and shorter duration. Adrenaline 1/200,000 did not appear to affect the area of segmental spread appreciably, but it doubled the duration and trebled the intensity of motor blockade in all concentrations tested. Latency of onset was irregularly affected by concentration and by addition of adrenaline. Analgesia developed fastest with 1 per cent and 5 per cent plain lignocaine, and with 3 per cent lignocaine with adrenaline, while 1 per cent and 5 per cent lignocaine with adrenaline gave the slowest onsets.

Philip R. Bromage

Papers

A Comparison of the Hydrochloride and Carbon Dioxide Salts of Lidocaine and Prilocaine in Epidural Analgesia

Concentrations of lignocaine in the blood after intravenous, intramuscular epidural and endotracheal administration

Spread of analgesic solutions in the epidural space and their site of action: a statistical study

Paraplegia following intracord injection during attempted epidural anesthesia under general anesthesia

Quality of epidural blockade i: influence of physical factors