Iatrogenic epidural spinal abscess.

We present four cases of iatrogenic epidural spinal abscess directly caused by externally introduced catheters or probes. In two patients the infection spread per continuum, in the other two patients due to haematogenous dissemination. Clinical presentation in each case included generalized malaise with fever, signs of meningeal inflammation and focal neurological signs at the spinal level. The diagnosis was made on the basis of inflammatory changes in the cerebral spinal fluid and localization of the abscess by means of computer and magnetic resonance tomography. A broad-spectrum antibiotic regimen included a penicillinase-resistant preparation because of the frequent involvement of Staphylococcus aureus. It is our experience that a good outcome is dependent on early and specific treatment.

Acid-base management during hypothermic cardiopulmonary bypass does not affect cerebral metabolism but does affect blood flow and neurological outcome.

In order to compare the effects of blood-gas management on cerebral blood flow, metabolism and neurological outcome after hypothermic cardiopulmonary bypass (CPB) we have studied 65 patients undergoing aorto-coronary bypass surgery allocated randomly to either a pH-stat (temperature-corrected blood-gas management) or an alpha-stat (temperature-uncorrected blood-gas management) group. All patients were examined neurologically on the day before and the 7th day after operation. In 20 patients of the pH-stat group and in 15 patients of the alpha-stat group we measured cerebral blood flow (CBF), using the argon washin technique, and also cerebral oxygen (CMRO2) and glucose (CMRg) uptake. Measurements were performed in awake patients, after induction of anaesthesia with fentanyl, midazolam and pancuronium under normothermic conditions, during CPB at a venous blood temperature of 26 degrees C and at the end of surgery. Compared with postinduction values, hypothermia was associated with an 18% reduction in CBF and decreases in CMRO2 and CMRg of 61% and 60%, respectively, in the alpha-stat group. In the pH-stat group, CMRO2 and CMRg decreased also, by 58% and 74%, respectively, whereas CBF increased by 191%, indicating uncoupling of flow and metabolism. As there were no statistically significant differences between the metabolic variables in both groups, we conclude that acid-base management did not affect cerebral metabolism, despite its influence on blood flow. After rewarming, CBF and cerebral metabolism normalized independently of acid-base management during hypothermia. Nevertheless, neurological dysfunction occurred more often in the pH-stat group (P = 0.036).

Penetration of rifampicin into the cerebrospinal fluid of adults with uninflamed meninges.

The penetration of rifampicin into CSF was studied in seven patients who had undergone external ventriculostomy for occlusive hydrocephalus without major disturbance of the blood-CSF barrier. After the first dose of rifampicin 600 mg i.v. over 3 h, blood and CSF concentrations were determined serially by HPLC. Peak CSF concentrations obtained 0-8 h (median = 1 h) after the end of the infusion ranged from 0.57 to 1.24 mg/L (median = 0.73 mg/L). Elimination from CSF was slower than from serum (T1/2 beta CSF: 9.1-21.0 h (median = 14.5 h, n = 5); T1/2 beta serum: 2.2-5.8 h (median = 3.6 h, n = 7)). Based on the ratios of the areas under the concentration-time curves in CSF and serum, the overall penetration of rifampicin into CSF was 0.13-0.42 (median = 0.22). These results demonstrate effective CSF penetration and favourable pharmacokinetics of rifampicin in the absence of meningeal inflammation. They support the use of rifampicin as part of a combination therapy not only for tuberculosis of the central nervous system (CNS), but also for staphylococcal and listerial infections of the CNS in which there may be little meningeal inflammation.

Passage of cefotaxime and ceftriaxone into cerebrospinal fluid of patients with uninflamed meninges.

Cefotaxime and ceftriaxone have proven to be effective in pyogenic infections of the central nervous system. Since in some bacterial central nervous system infections the blood-cerebrospinal fluid (CSF) barrier is either minimally impaired or recovers in the course of the illness, we studied the penetration of both antibiotics in the absence of inflamed meninges. Patients who had undergone external ventriculostomies for noninflammatory occlusive hydrocephalus received either cefotaxime (2 g/30 min) or ceftriaxone (2 g/30 min) to treat extracerebral infections. Serum and CSF were drawn repeatedly after the first dose. With ceftriaxone, they were also drawn after the last dose. The concentrations of cefotaxime, its metabolite desacetylcefotaxime, and ceftriaxone were determined by high-performance liquid chromatography with UV detection. Maximum concentrations of cefotaxime in CSF were reached 0.5 to 8 h (median = 3 h; n = 6) after the end of the infusion and ranged from 0.14 to 1.81 mg/liter (median = 0.44 mg/liter; n = 6). Maximum levels of ceftriaxone in CSF ranging from 0.18 to 1.04 mg/liter (median = 0.43 mg/liter; n = 5) were seen 1 to 16 h (median = 12 h; n = 5) after the infusion. The elimination half-life of cefotaxime in CSF was 5.0 to 26.9 h (median = 9.3 h; n = 5), and that of ceftriaxone was 15.7 to 18.4 h (median = 16.8 h; n = 3). It is concluded that after a single dose of 2 g, maximal concentrations of cefotaxime and ceftriaxone in CSF do not differ substantially. The long elimination half-lives guarantee uniform concentrations in CSF. These concentrations reliably inhibit highly susceptible bacteria but cannot be relied on to inhibit staphylococci and penicillin G-resistant Streptococcus pneumoniae.