Anatomy and pathophysiology of the sacroiliac joint.

The sacroiliac joint as a source of chronic pain has been a subject of debate for a long period of time. This controversy stems from the inherent anatomic location of the sacroiliac joint. Adjacent spinal structures may cause pain to be referred to the sacroiliac joint, thus making a precise diagnosis difficult. The most reliable method to establish the diagnosis of sacroiliac arthralgia is fluoroscopic-guided intra-articular injection of a local anesthetic preceded by a sacroiliac arthrogram. Although there are many therapeutic options for sacroiliac joint syndrome, the ideal treatment has not yet been discovered. There is evidence that intra-articular viscosupplementation of the sacroiliac joint with hylan can consistently and reliably induce a prolonged analgesic response in sacroiliac joint syndrome. Viscosupplementation restores joint homeostasis, allows increased joint motion, and induces analgesia. Hylan is highly viscoelastic hyaluronan (hyaluronic acid), and is capable of increasing the viscoelastic properties of synovial fluid.

Computed tomography-guided pudendal nerve block. A new diagnostic approach to long-term anoperineal pain: a report of two cases.

OBJECTIVE: To show the value of computed tomography (CT) in selectively blocking the pudendal nerve in patients with long-term anogenital pain of uncertain etiology. We report a technique to selectively block the pudendal nerve using CT guidance in 2 patients with long-term anogenital pain. CASE REPORT: In 1 patient, a competitive cyclist, the diagnosis of pudendal neuralgia was substantiated by blocking the nerve under CT. The procedure relieved the pain for approximately 24 hours. In the other patient, pudendal nerve block produced perineal analgesia but no pain relief. Superior hypogastric plexus block relieved the pain significantly for about 4 weeks on 2 separate occasions, suggesting sympathetically maintained pain. CONCLUSION: The use of CT to guide the procedure allowed precision in performing the procedure and in making a differential diagnosis.

Intravenous infusion of 4-AP in chronic spinal cord injured subjects.

STUDY DESIGN: A prospective double blind cross over trial of intravenous 4-Aminopyridine (4-AP). OBJECTIVE: To determine the efficacy of this drug in the treatment of spinal cord injured (SCI) patients for neurologic impairment, pain and spasticity. SETTING: The post anesthesia care unit (PACU) of a tertiary care acute hospital. METHODS: Twelve paraplegic patients were enrolled in a double blind cross over intravenous trial of 4-Aminopyridine (4-AP). Thirty milligrams of 4-AP or placebo were administered over a 2 h period. Patients were serially examined during and after the infusion clinically for pain, sensorimotor function, hypertonicity and motor control using electromyography (EMG). Samples of blood and cerebrospinal fluid (CSF) were also analyzed at similar intervals. RESULTS: Despite penetration of 4-AP into the CSF, no significant differences were noted in the clinical and EMG parameters at the times measured. Individual changes in sensory function were reported by some patients in both the placebo and 4-AP trials, however mean values were not robust. Frequently, patients complained of unpleasant symptoms during the 4-AP infusion. CONCLUSION: The intravenous route may not be the best way to administer this drug as no short term benefits were observed.

Intrathecal administration of 4-aminopyridine in chronic spinal injured patients.

STUDY DESIGN: Intrathecal administration of 4-aminopyridine (4-AP) in chronic spinal cord injured (SCI) patients. OBJECTIVE: To determine the safety and effects of intrathecal administration of 4-AP in a small population of chronic SCI patients. SETTING: The post anesthesia care unit of a tertiary care hospital. METHODS: Following animal mode studies to establish dosing safety, six subjects with chronic SCI were examined. In each subject, an intrathecal catheter was placed with the tip as close to the lesion level as possible. 4-AP was infused at 5 microg/h for a period of 4-5 h. Vital signs were recorded and sensory-motor physical examinations and pain questionnaires were administered for 24 h. In two patients, samples of cerebrospinal fluid for analysis were drawn from a second intrathecal catheter. RESULTS: No adverse systemic side effects were noted. One patient showed transient improvement in sensory function; two showed transient increases in spasticity; three showed transient increases in cutaneomuscular reflexes and two showed an apparent small increase in volitional motor control. The concentration of 4-aminopyridine in the cerebrospinal fluid reached a peak of 163 ng/ml at 4 h in one subject and 122 ng/ml at 5 h in the other subject examined. CONCLUSION: Intrathecal administration of 4-aminopyridine at a rate of 5 microg/h does not appear to cause adverse effects and may modify spinal cord function. This route of administration allows local cerebrospinal fluid concentrations equivalent to those produced by maximum tolerable systemic doses, which require 1000 times more drug substance to be delivered to the subject as a whole. Intrathecal administration offers the potential to focus therapeutic effects to the lesion site while minimizing systemic side effects.

Viscosupplementation: a new concept in the treatment of sacroiliac joint syndrome: a preliminary report of four cases.

BACKGROUND AND OBJECTIVES: We describe a new therapeutic modality for sacroiliac joint syndrome that represents an alternative to other treatment modalities. We report on four cases of sacroiliac joint syndrome with severe pain. METHODS: Three patients had undergone operative treatment of the lumbar spine and one patient suffered from severe osteoarthritis of the spine. All patients were diagnosed with sacroiliac joint syndrome by means of patient history, physical examination, and intra-articular local anesthetic injection preceded by sacroiliac arthrogram. All patients received three injections of Hylan GF 20 in the sacroiliac joints 2 weeks apart. RESULTS: Twelve to 16 weeks after the injections, the pain was reported to be 40-67% better when measured on the visual analog scale. The duration of the beneficial effect of Hylan on arthralgia and joint function was undetermined. CONCLUSIONS: Viscosupplementation of the sacroiliac joint induced a significant degree of analgesia in all four patients. This treatment modality could represent an option in the management of sacroiliac joint pain and dysfunction.

Neuroaugmentation in the treatment of complex regional pain syndrome of the upper extremity.

The authors report their results on 36 patients with advanced stages of complex regional pain syndrome. They were treated with either spinal cord stimulation, or peripheral nerve stimulation, and in some cases with both modalities. Thirty six months after implantation the reported pain measured on visual analogue scales was an average of 53% better, this change was statistically significant. Analgesic consumption decreased by about 50% or was reportedly more effective. The authors conclude that in late stages of complex regional pain syndrome, neuroaugmentation is a reasonable option when alternative therapies have failed.

Neuroaugmentation in the management of sacroiliac joint pain. Report of two cases.

STUDY DESIGN: A report of two cases of severe sacroiliac pain that were resistant to conventional management techniques. Both patients had undergone lumbar fusion. This appeared to be a predisposing factor. OBJECTIVE: To define the source of pain in these patients by performing a series of diagnostic blocks under fluoroscopic guidance to determine if these patients were candidates for neuroaugmentation. SUMMARY OF BACKGROUND DATA: Mild to moderate sacroiliac joint pain can be managed conservatively with analgesics, anti-inflammatory drugs, and physical therapy. Severe sacroiliac joint pain can be incapacitating and more challenging to manage. Fluoroscopically guided intra-articular local anesthetic-steroid injections, followed by joint manipulation, can be effective, intracapsular injections of glycerin, glucose, and phenol also may be beneficial in some patients. The use of neuroaugmentation to manage pain of synovial origin has not been reported previously. Sacral nerve root stimulation in particular has been used to manage urinary bladder dysfunction and pain, but not sacroiliac joint pain. METHODS: Two patients with severe sacroiliac joint pain were treated by implanting a neuroprosthesis at the third sacral nerve roots. The patients had undergone lumbar fusion for back pain that developed as a result of work-related injuries. Stimulation was tried for 1 week with bilateral, percutaneously implanted, cardiac pacing wires at the third sacral nerve roots. RESULTS: Both patients experienced relief of approximately 60% of their pain during the trial period. Therefore, a neuroprosthesis (Medtronics, MN) was implanted permanently bilaterally at the third sacral nerve root in both patients. The use of analgesics was reportedly the same after implantation, but significantly more effective, and the patients' daily living activities were more tolerable. CONCLUSIONS: Two cases of refractory sacroiliac joint pain are reported that were managed with permanently implanted neuroprostheses at the third sacral nerve roots. The authors suggest that neuroaugmentation can be a reasonable option in selected patients with refractory sacroiliac pain.

Thermal grill illusion and complex regional pain syndrome type I (reflex sympathetic dystrophy).

BACKGROUND AND OBJECTIVES: In normal humans, placing a hand on a thermal grill containing warm elements separated by cool ones produces a burning sensation. In this case report, responses to a thermal grill in a patient with neuropathic pain were examined. METHODS: The responses of a 31-year-old woman with complex regional pain syndrome type I (reflex sympathetic dystrophy) to a thermal grill were evaluated before and after stellate ganglion block. RESULTS: The patient experienced a burning sensation when the unaffected hand was placed on the grill and could distinguish which element was warm and which was cool. An intolerable burning sensation caused the patient to quickly (within 4 seconds) withdraw the affected hand when it was placed on the grill. Touching cool elements with the affected hand produced an intense burning sensation (cold allodynia), whereas touching warm elements produced a pleasant warm sensation. Stellate ganglion block with phenol, local anesthetic, and steroid resulted in long-lasting absence of cold allodynia. CONCLUSION: The thermal grill may be a useful a tool to help understand the pathophysiology of complex regional pain syndrome type I.

Complex regional pain syndrome type 2 (causalgia) after automated laser discectomy. A case report.

STUDY DESIGN: This report identifies a case of complex regional pain syndrome Type 2 (causalgia) with sympathetically maintained pain associated with automated laser discectomy. The syndrome's clinical features and its management with sympathectomy are described. OBJECTIVES: To report an unusual complication associated with automated laser discectomy, review the possible mechanism, and discuss the management of complex regional pain syndrome Type 2 with sympathetically maintained pain. SUMMARY OF BACKGROUND DATA: Automated laser discectomy represents a minimally invasive technique to treat herniated intervertebral discs. By using small, automated probes placed in the disc under local anesthesia and fluoroscopic guidance, disc material can be removed percutaneously, eliminating the need for lumbar laminectomy with its attendant morbidity. Some complications have been reported. This case report presents a complication not previously described. METHODS: A 39-year-old woman underwent L4-L5 automated laser discectomy; an attempt was made to lase the L5-S1 disc, but the procedure was aborted because of severe pain and discomfort. The patient had pain in the left lower extremity in the L5 and S1 distribution, including the foot. There was evidence of allodynia and hyperesthesia with some dystrophic changes in the foot. A diagnosis of complex regional pain syndrome Type 2 (causalgia) was made. RESULTS: A series of two diagnostic percutaneous chemical sympathectomies were undertaken, and the pain was relieved to a significant extent for up to 2 weeks. This suggested complex regional pain syndrome Type 2 with sympathetically maintained pain, and thereafter therapeutic chemical sympathectomy resulted in resolution of the pain syndrome. CONCLUSIONS: Complex regional pain syndrome Type 2 with sympathetically maintained pain is a condition that can result in serious disability and can be associated with a number of spinal procedures, including automated laser percutaneous discectomy. Early intervention is recommended to provide long-term resolution of the condition.

Anesthesia for ophthalmic surgery in the elderly: the effects of clonidine on intraocular pressure, perioperative hemodynamics, and anesthetic requirement.

The effects of clonidine on intraocular pressure and perioperative cardiovascular variables were studied by a randomized double blind design in 80 elderly patients (ASA physical status I-III) scheduled for elective ophthalmic surgery under general anesthesia (GA) and local anesthesia (LA). Group 1 (n = 40), the control group, received diazepam po (0.1 mg.kg-1) 90-120 min prior to arrival to the operating room. Group 2 (n = 40) received clonidine po approximately 5 micrograms.kg-1 po at the same time. Each group was divided into subgroups of 20 patients each to be managed with GA (GA subset) or LA (LA subset). Ninety to 120 minutes after the premedication, a large decrease in IOP from 20 +/- 3 to 12 +/- 3 mmHg (P less than 0.01) and a small but significant reduction of both systolic and diastolic BP and HR were observed in patients receiving clonidine, while no changes occurred in controls. In the patients managed with GA, clonidine effectively prevented IOP rise and attenuated the associated cardiovascular response (P less than 0.01) following laryngoscopy and tracheal intubation, and significantly reduced intraoperative cardiovascular lability and anesthetic requirement for isoflurane (P less than 0.05) and for fentanyl (P less than .001). In patients managed with LA, intraoperative systolic (P less than 0.01) and diastolic BP and HR variability (P less than 0.05) were significantly lower in patients receiving clonidine as compared to controls. Intraoperatively, a significantly higher incidence of hypertension (P less than 0.01) and tachycardia (P less than 0.05) were respectively observed in the LA subset and GA subset of the controls when contrasted with the corresponding subset of those receiving clonidine. Moreover, clonidine was more effective than diazepam as a premedication; in fact, satisfactory intraoperative sedation and cardiovascular stability were observed in 85% of the patients who received clonidine, and in 50% of those patients who did not receive clonidine (P less than 0.01). Thus, clonidine may represent a useful adjunct in the management of the aged patient in the setting of ophthalmic surgery.

Anesthesia and hypertension: the effect of clonidine on perioperative hemodynamics and isoflurane requirements.

Thirty patients (ASA physical status II-III) with a history of arterial hypertension, whose blood pressure (BP) control varied from normotension to moderate hypertension (diastolic BP less than 110 mmHg), scheduled for elective surgery under general anesthesia, were randomly assigned to two groups. Group 1 was premedicated 90-120 min prior to induction with diazepam 0.15 mg X kg-1 po; group 2, in addition, received clonidine 5 micrograms X kg-1 po. Anesthetic depth was assessed by on-line aperiodic analysis of the electroencephalogram. Following lidocaine 1 mg X kg-1 and fentanyl 2 micrograms X kg-1 (group 1 only), anesthesia was induced with thiopental 3-4 mg X kg-1 and vecuronium 0.1 mg X kg-1 was used to facilitate endotracheal intubation. Anesthesia was maintained with isoflurane in N2O/O2 and supplemented by fentanyl. In group 2, clonidine produced a rapid preoperative control of systolic and diastolic BP from 166 +/- 32/95 +/- 14 to 136 +/- 80 +/- 11 (P less than 0.01), was more effective in blunting the reflex tachycardia associated with laryngoscopy and endotracheal intubation than lidocaine-fentanyl pretreatment. It significantly reduced the intraoperative lability (coefficient of variation) of systolic (P less than 0.01) and diastolic BP and heart rate (HR) (P less than 0.05), and resulted in significantly slower HR during recovery (P less than 0.01). Anesthetic requirements for isoflurane were reduced 40% (P less than 0.01) in group 2; narcotic supplementation was also significantly reduced (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Haemodynamic effects of clonidine injected epidurally in halothane-anaesthetized dogs.

The haemodynamic effects of clonidine administered in the epidural space were studied in 16 halothane-anaesthetized dogs. The animals were randomly assigned to two groups: Group I received three doses of 3 ml of normal saline, Group II received three doses of 3 micrograms X kg-1 of clonidine, through an epidural catheter, whose tip was located between L2-T11. Control haemodynamic measurements were taken one hour after completion of the surgical preparation (period P1); they were repeated every 45 minutes after each incremental dose (periods P2, P3, P4) and 105 minutes after a total cumulative dose of 9 micrograms X kg-1 of clonidine or 9 ml of saline were given (period P5). No significant changes over time were observed in Group I. In Group II clonidine produced statistically significant reductions of systemic blood pressure (BP), mean left ventricular pressure (LV), heart rate (HR), cardiac output (CO) and peak LV dP/dt only after a total clonidine dose of 9 micrograms X kg-1 and these changes were sustained. BP fell 15 per cent, CO 21 per cent, HR 25 per cent, LV 20 per cent and peak LV dP/dt 30 per cent when P5 measurements were compared to control values within Group II (p less than 0.05). These haemodynamic effects of clonidine are likely due to minimal systemic absorption and/or cephalad spread of the drug towards its site of action in the brain stem. The reductions of HR, CO, BP, and isovolemic indices of contractility are likely explained by a reduction of sympathetic outflow at the spinal cord and medulla oblongata levels as well as increased parasympathetic tone.(ABSTRACT TRUNCATED AT 250 WORDS)

Presynaptic effect of clonidine on unmyelinated afferent fibers in the spinal cord of the cat.

The effects of clonidine (Clo) were investigated on the excitability of intraspinal primary afferent terminals of both A- and C-fibers of cutaneous origin. Primary afferent terminal excitability was tested by delivering constant current pulses to the dorsal horn of acutely spinalized cats anesthetized with pentobarbital. Clo given i.v. selectively increased the excitability of the C-fiber primary afferent terminals (mean 85%). Primary afferent terminal excitability of A-fibers was not affected. This effect of Clo was reversed by yohimbine or phentolamine, thus suggesting mediation by alpha2-adrenoceptors. These findings suggest a presynaptic inhibitory effect of Clo in spinal nociceptive pathways that might explain the mechanism of action of this drug.

Effects of clonidine on narcotic requirements and hemodynamic response during induction of fentanyl anesthesia and endotracheal intubation.

The effects of clonidine, a centrally acting alpha 2-adrenergic receptor agonist, on depth of fentanyl anesthesia and on cardiovascular response to laryngoscopy and intubation were studied. Twenty-four patients undergoing aortocoronary bypass surgery (ACBS) with a history of arterial hypertension, coronary artery disease (NYHA class 3-4), and well-preserved left ventricular function were assigned randomly to either Group 1 (n = 12), who received standard premedication, or Group 2 (n = 12), who received clonidine 5 micrograms X kg-1 po in addition to standard premedication 90 min before estimated induction time. Depth of anesthesia was assessed by on-line aperiodic computerized analysis of the electroencephalogram (Lifescan EEG Monitor). Fentanyl was administered in 250-micrograms increments to shift the EEG to the 0.5-3-Hz frequency range (delta activity) in all subjects. In both groups, the anesthetic regimen effectively prevented hyperdynamic cardiovascular responses to laryngoscopy and intubation. No significant differences in measured or derived hemodynamic variables were observed between the two groups during the awake control period, except for stroke volume index (SVI), which was significantly greater in Group 1, 44 +/- 9 ml X beat-1 X m-2 compared with Group 2, 35 +/- 3.3 ml X beat-1 X m-2 (P less than 0.05). By contrast, fentanyl requirements in Group 2 were significantly reduced by 45% when compared with Group 1, i.e., from 110 +/- 23 to 61 +/- 19 micrograms X kg-1 (P less than 0.001). The authors conclude that at a similar anesthetic depth, as assessed by the EEG shift into the lower frequency range (0.5-3 Hz), a markedly reduced fentanyl dose effectively prevented the hyperdynamic cardiovascular response to laryngoscopy and intubation in the group of patients premedicated with clonidine. This is likely explained by the known synergistic inhibitory action of opiates and alpha 2-adrenoceptor agonists on central sympathetic outflow.

Presynaptic depolarization of unmyelinated primary afferent fibers in the spinal cord of the cat.

Low intensity (1-20 micro A) intraspinal stimulation produces in the sural nerve of the anesthetized cat short latency responses (3-4 ms) due to antidromic activation of fibers conducting in the A range (43-65 m/s). With higher stimulus intensities (up to 400 micro A) late responses (120-250 ms latency) may also be recorded. Simultaneous recording from two sites in the sural nerve shows that the peripheral processes of the fibers generating the late responses have a conduction velocity between 0.8-1.3 m/s. Collision between antidromic and orthodromic responses further indicates that these fibers have a peripheral threshold 20-25 times that of the A fibers. The late responses were largest when the intraspinal stimulating electrode was located in the dorsal horn, in the region corresponding to Laminae II and III of Rexed. The above observations suggest that the late responses are due to population responses of C fibers which are antidromically activated in the dorsal horn. The excitability of the C fiber terminals is increased by conditioning stimuli applied to other cutaneous afferents with a time course resembling that of the excitability increase of the A fibers on the same nerve. It is suggested that the effectiveness of synaptic transmission from C fibers to second order cells may be modulated presynaptically. In the decerebrate cat the antidromic responses of C fibers are reduced, but not abolished, by reversible spinalization produced by cooling or by sectioning the thoracic spinal cord. This suggests in addition that in the decerebrate preparation the presynaptic effectiveness of the C fiber (presumably nociceptive) input may be tonically decreased by supraspinal influences.

Action of narcotic analgesics and antagonists on spinal units responding to natural stimulation in the cat.

Morphine and morphine-related agents were applied by microiontophoresis in the lumbar spinal cord of spinal cats to single units classified on the basis of their responses to natural cutaneous or proprioceptive stimulation. Opiate application had a current-dependent depressant effect on the ongoing activities of about one-third of the units tested. This effect was observed in laminae I and IV--VI, but only with units responding to noxious cutaneous stimuli: the nociceptive responses were themselves depressed. Excitatory and inhibitory responses to glutamate and gamma-aminobutyric acid, respectively, were also depressed. Intravenous administration of the opiates at doses reported to produce analgesia in the cat also depressed only units responding to noxious cutaneous stimuli, including their nociceptive responses. This depression could be reversed by either the iontophoretic application (100 nA) or the intravenous administration (0.1--0.8 mg/kg) of naloxone. These results are interpreted as further evidence that the analgesic effects of opiates are at least partly due to an action at the spinal level.

Primary afferent depolarization of C fibres in the spinal cord of the cat.

The excitability of primary afferent terminals of cutaneous C fibres was tested in the spinal cord of decerebrated cats. C fibre terminal excitability was decreased in the spinal state, and increased by conditioning volleys that activated only A fibres of another cutaneous nerve and by stimulating hair mechanically. It is suggested that C fibre input and therefore nociceptive information to the central nervous system is susceptible to presynaptic control by segmental and suprasegmental mechanisms.