Detection of osteomyelitis in the neuropathic foot: nuclear medicine, MRI and conventional radiography.

The diagnostic efficacy of (1) combined three-phase bone scintigraphy and In-111 labeled WBC scintigraphy (Bone/WBC), (2) MRI, and (3) conventional radiography in detecting osteomyelitis of the neuropathic foot was compared. Conventional radiography was comparable to MRI for detection of osteomyelitis. MRI best depicted the presence of osteomyelitis in the forefoot. Particularly in the setting of Charcot joints, Bone/WBC was more specific than conventional radiography or MRI.

Diminished cerebrospinal fluid beta-endorphin concentration in monkeys with arachnoiditis.

Altered concentrations of brain beta endorphin and spinal cord encephalin have been reported in mice with iatrogenic arachnoiditis. We measured beta-endorphin concentration in cerebrospinal fluid (CSF) in normal monkeys and in monkeys with various degrees of arachnoiditis resulting from myelography and spinal surgery and found a significant negative correlation between the arachnoiditis score and the lumbar CSF beta-endorphin concentration. This study suggests that an assay of CSF beta endorphin can be used to detect the alterations in neurotransmitters in arachnoiditis.

Effect of arachnoiditis on pain threshold.

A model for studying the relationship between chronic arachnoiditis and pain sensitivity was developed. Thirty male ICR mice were randomly divided into three groups and the tail-flick test was done using an EMDIE-TF6 apparatus (Emdie Instrument Co., Montpelier, VA). Ten mice were injected intrathecally with 5.0 microL of a kaolin-metrizamide mixture and ten control mice were injected intrathecally with 5.0 microL of an electrolyte solution resembling CSF. A third group, (naive controls) were given no treatment. Six weeks later tail-flick tests were repeated. The kaolin-treated mice had significantly decreased tail-flick latencies (P less than .05) compared with the baseline; the controls had no significant change in tail-flick latency. Histologic examination revealed moderate to severe arachnoiditis in the kaolin-treated animals and no evidence of arachnoid abnormalities in the controls. This study suggests that arachnoiditis may be associated with decreased pain thresholds.

Brain beta-endorphin and spinal-cord enkephalin concentrations in experimental arachnoiditis.

Arachnoiditis was produced experimentally in male albino ICR mice by intrathecal injection of meglumine iocarmate . A control group received intrathecal injection of an electrolyte solution resembling CSF. Eight weeks after injection, the brains and spinal cords were removed for brain beta-endorphin and spinal cord met-enkephalin measurement by radioimmunoassay, and the dural sacs were removed for histologic examination to confirm the presence or absence of arachnoiditis. Brain beta-endorphin content was significantly reduced and spinal-cord enkephalin concentration was significantly elevated in iocarmate-treated animals. The dura and arachnoid in the treated mice were thickened and infiltrated with lymphocytes. These studies indicate that arachnoiditis alters endogenous polypeptide concentrations.

Arachnoiditis from myelography and laminectomy in experimental animals.

Clinical reports have suggested that myelography and laminectomy may produce more arachnoiditis than myelography alone. The effect of experimental lumbar myelography and laminectomy on arachnoiditis in monkeys was studied. Arachnoiditis was as severe after myelography alone as after myelography and laminectomy. Minimal arachnoiditis was found myelographically and histologically after myelography with metrizamide 300 mg l/ml, and severe arachnoiditis was found after myelography with iophendylate whether or not laminectomy was performed. Laminectomy alone produced insignificant arachnoid changes. Experimental myelography preceding laminectomy did not increase the risk of arachnoiditis.

Experimental study of arachnoiditis from iohexol, an investigational nonionic aqueous contrast medium.

Myelography was performed in 16 monkeys using either metrizamide or iohexol, a new nonionic aqueous contrast medium. Eight of the animals received almost five times the recommended clinical dose of contrast medium per unit of body weight; the other eight received the equivalent of a high clinical dose. The severity of resultant arachnoiditis 12 weeks later was evaluated by repeat myelography and by histologic study of the arachnoid. No animals had severe arachnoiditis. Two of the four animals examined with the higher dose of metrizamide had moderate arachnoiditis and one had mild arachnoiditis; with the lower dose of metrizamide, two of four animals had mild arachnoiditis. No significant evidence of arachnoiditis was seen in any of the eight animals examined with iohexol.