First-ever acute ischemic strokes in HIV-infected persons: A case-control study from stroke units

OBJECTIVE

The stroke risk for persons living with human immunodeficiency virus (PLHIVs) doubled compared to uninfected individuals. Stroke-unit (SU)-access, acute reperfusion therapy-use and outcome data on PLHIVs admitted for acute ischemic stroke (AIS) are scarce.

METHODS

AIS patients admitted (01 January 2017 to 31 January 2021) to 10 representative Paris-area SUs were screened retrospectively from the National Hospitalization Database. PLHIVs were compared to age-, initial NIHSS- and sex-matched HIV-uninfected controls (HUCs). Outcome was the 90-day modified Rankin Scale score.

RESULTS

Among 126 PLHIVs with confirmed first-ever AIS, ~80% were admitted outside the thrombolysis-administration window. Despite antiretrovirals, uncontrolled plasma HIV loads exceeded 50 copies/mL (26% of all PLHIVs; 38% of those ≤55 years). PLHIVs' stroke causes by decreasing frequency were large artery atherosclerosis (LAA), undetermined, other cause, cerebral small-vessel disease (CSVD) or cardioembolism. No stroke etiology was associated with HIV duration or detectable HIVemia. MRI revealed previously unknown AIS in one in three PLHIVs, twice the HUC rate (p = 0.006). Neither group had optimally controlled modifiable cardiovascular risk factors (CVRFs): 20%-30% without specific hypertension, diabetes, and/or dyslipidemia treatments. Their stroke outcomes were comparable. Multivariable analyses retained good prognosis associated solely with initial NIHSS or reperfusion therapy. Older age and hypertension were associated with CSVD/LAA for all PLHIVs. Standard neurovascular care and reperfusion therapy were well-tolerated.

INTERPRETATION

The high uncontrolled HIV-infection rate and suboptimal CVRF treatment support heightened vigilance to counter suboptimal HIV suppression and antiretroviral adherence, and improve CVRF prevention, mainly for younger PLHIVs. Those preventive, routine measures could lower PLHIVs' AIS risk.

Persistent headaches one year after bacterial meningitis: prevalence, determinants and impact on quality of life

BACKGROUND

Little is known on headaches long-term persistence after bacterial meningitis and on their impact on patients' quality of life.

METHODS

In an ancillary study of the French national prospective cohort of community-acquired bacterial meningitis in adults (COMBAT) conducted between February 2013 and July 2015, we collected self-reported headaches before, at onset, and 12 months (M12) after meningitis. Determinants of persistent headache (PH) at M12, their association with M12 quality of life (SF 12), depression (Center for Epidemiologic Studies Depression Scale) and neuro-functional disability were analysed.

RESULTS

Among the 277 alive patients at M12 87/274 (31.8%), 213/271 (78.6%) and 86/277 (31.0%) reported headaches before, at the onset, and at M12, respectively. In multivariate analysis, female sex (OR: 2.75 [1.54-4.90]; p < 0.001), pre-existing headaches before meningitis (OR: 2.38 [1.32-4.30]; p < 0.01), higher neutrophilic polynuclei percentage in the CSF of the initial lumbar puncture (OR: 1.02 [1.00-1.04]; p < 0.05), and brain abscess during the initial hospitalisation (OR: 8.32 [1.97-35.16]; p < 0.01) were associated with M12 persistent headaches. Neither the responsible microorganism, nor the corticoids use were associated with M12 persistent headaches. M12 neuro-functional disability (altered Glasgow Outcome Scale; p < 0.01), M12 physical handicap (altered modified Rankin score; p < 0.001), M12 depressive symptoms (p < 0.0001), and M12 altered physical (p < 0.05) and mental (p < 0.0001) qualities of life were associated with M12 headaches.

CONCLUSION

Persistent headaches are frequent one year after meningitis and are associated with quality of life alteration.

CLINICAL TRIAL

NCT01730690.

Diagnosis and management of hepatic encephalopathy: The French recommendations

Hepatic encephalopathy (HE) is a frequent and severe complication of liver disease with poor patient outcomes. However, it is a poorly understood complication, with no consensus for diagnosis. Therefore, HE is often underdiagnosed. Differential diagnosis may be cumbersome because of non-specific symptoms, such as confusion, cognitive disorders, the aetiological factors of cirrhosis and comorbidities, which are often observed in cirrhotic patients. Therefore, an overt or covert form of HE should be systematically investigated. Advice is provided to drive patient work-up. Effective treatments are available to prevent or treat HE bouts, but the issue of single or combination therapy has not been resolved. Transjugular intrahepatic portosystemic shunt (TIPS) placement largely improved the prognosis of cirrhotic patients, but HE occurrence of HE is often a fear, even when post-TIPS HE can be avoided by a careful selection of patients and preventive treatment. HE is an indication of liver transplantation. However, its reversibility post-transplantation and the consequences of transplantation in patients with other causes of neurological disorders remain controversial, which supports the performance of an extensive work-up in expert centres for this subset of patients. The present guidelines assist clinicians in the diagnosis of the overt or covert form of HE to implement curative and preventive treatments and clarify which patients require referral to expert centres for consideration for liver transplantation. These guidelines are very clinically oriented and address different frequent clinical issues to help physicians make bedside decisions.

FIP1L1-PDGFRA-Associated Hypereosinophilic Syndrome as a Treatable Cause of Watershed Infarction

BACKGROUND AND PURPOSE

Ischemic stroke has been reported in various conditions associated with eosinophilia. FIP1L1-PDGFRA fusion ([Fip1-like 1-platelet-derived growth factor receptor alpha]; F/P) leads to the proliferation of the eosinophilic lineage and thus to a clonal hypereosinophilic syndrome that is highly responsive to imatinib.

METHODS

We previously reported on a nationwide retrospective study of 151 patients with F/P-associated clonal hypereosinophilic syndrome. Patients from this cohort with a clinical history of ischemic stroke (as well as 2 additional cases) were further analyzed to better define their clinical picture and outcomes.

RESULTS

Sixteen male patients (median age, 51 [43-59] years) with low-to-intermediate cardiovascular risk were included. Median National Institutes of Health Stroke Scale was 4 (range, 1-6). Most cerebral imaging disclosed multiple bilateral infarctions of watershed distribution (69%). Despite frequent cardiac involvement (50%), cardiac thrombus was evidenced in a single patient and, according to the TOAST classification (Trial of ORG 10172 in Acute Stroke Treatment), 62.5% of strokes were presumably of undetermined etiology. Among the 15 patients treated with imatinib, and after a median follow-up of 4.5 years, stroke recurred in only 3 patients (consisting of either cardio embolic or hemorrhagic events, unrelated to the first episode).

CONCLUSIONS

F/P+ clonal hypereosinophilic syndrome is a diagnosis to consider in patients with unexplained ischemic stroke and hypereosinophilia (especially in the setting of multiple cortical borderzone distribution) and warrants prompt initiation of imatinib.

Clinical Outcome of Acute Ischemic Strokes in Patients with COVID-19

INTRODUCTION

Acute ischemic stroke (AIS) and thrombotic events (TEs) were reported in patients with COVID-19. Clinical outcome of AIS in the course of COVID-19 remains unknown. We compared early clinical outcome and mortality of COVID-positive (+) patients admitted for AIS with COVID-negative (-) ones. We hypothesized that COVID+ patients would have poorer clinical outcomes and present a higher rate of TEs and mortality compared with COVID- ones.

METHODS

In this multicentric observational retrospective study, we enrolled patients over 18 years old admitted for AIS in 3 stroke units of the Parisian region during lockdown from March 17, 2020, to May 2, 2020. COVID-19 status as well as demographic, clinical, biological, and imaging data was collected retrospectively from medical records. Poor outcome was defined as modified Rankin score (mRS) 3-6 (3-6) at discharge. We also compared TE frequency and mortality rate through a composite criterion in both groups.

RESULTS

Two hundred and sixteen patients were enrolled; mean age was 68 years old, and 63% were male. Forty patients were CO-VID+ (18.5%) and 176 were COVID-. Obesity was statistically more frequent in the COVID+ group (36 vs. 13% p < 0.01). The percentage of patients with mRS (3-6) at discharge was higher in the COVID+ group compared with the COVID- group (60 vs. 41%, p = 0.034). The main predictor of presenting a mRS (3-6) at discharge was high NIHSS score at admission (OR, CI 95%: 1.325, 1.22-1.43). Mortality rate was higher in the COVID+ group (12 vs. 3.4%, p = 0.033) as well as TE frequency (15 vs. 2.8%, p < 0.01).

CONCLUSION

In this study, patients with AIS infected by SARS-CoV-2 showed a poorer early outcome than COVID- ones. However, when compared to other factors, COVID-19 was not a significant predictor of poor outcome. Vascular morbidity and mortality rates were significantly higher in the COVID+ group compared with the COVID- group.

Fever is a common onset feature of MOG-IgG associated disorders (MOGAD)

BACKGROUND

Fever is a deceptive feature of autoimmune disorders. Although cases of MOG-IgG associated disorders (MOGAD) were rarely associated with fever, this association was not specifically described.

METHODS

We report a case of MOGAD revealed by weeks of fever and meningitis. We reviewed the current literature to describe the association between fever and MOGAD.

RESULTS

We analyzed 146 cases from the literature including ours. Fever was associated with 39% of MOGAD attacks and lasted more than a week in 74%. Fever was strongly associated with brain and spinal cord attacks, and with meningitis.

CONCLUSION

Among the various features of MOGAD, fever is a highly prevalent associated symptom that should be kept in mind.

Post-Thrombolysis Recanalization in Stroke Referrals for Thrombectomy

Background and Purpose—

Whether all acute stroke patients with large vessel occlusion need to undergo intravenous thrombolysis before mechanical thrombectomy (MT) is debated as (1) the incidence of post-thrombolysis early recanalization (ER) is still unclear; (2) thrombolysis may be harmful in patients unlikely to recanalize; and, conversely, (3) transfer for MT may be unnecessary in patients highly likely to recanalize. Here, we determined the incidence and predictors of post-thrombolysis ER in patients referred for MT and derive ER prediction scores for trial design.

Methods—

Registries from 4 MT-capable centers gathering patients referred for MT and thrombolyzed either on site (mothership) or in a non MT-capable center (drip-and-ship) after magnetic resonance– or computed tomography–based imaging between 2015 and 2017. ER was identified on either first angiographic run or noninvasive imaging. In the magnetic resonance imaging subsample, thrombus length was determined on T2*-based susceptibility vessel sign. Independent predictors of no-ER were identified using multivariable logistic regression models, and scores were developed according to the magnitude of regression coefficients. Similar registries from 4 additional MT-capable centers were used as validation cohort.

Results—

In the derivation cohort (N=633), ER incidence was ≈20%. In patients with susceptibility vessel sign (n=498), no-ER was independently predicted by long thrombus, proximal occlusion, and mothership paradigm. A 6-point score derived from these variables showed strong discriminative power for no-ER (C statistic, 0.854) and was replicated in the validation cohort (n=353; C statistic, 0.888). A second score derived from the whole sample (including negative T2* or computed tomography–based imaging) also showed good discriminative power and was similarly validated. Highest grades on both scores predicted no-ER with >90% specificity, whereas low grades did not reliably predict ER.

Conclusions—

The substantial ER rate underlines the benefits derived from thrombolysis in bridging populations. Both prediction scores afforded high specificity for no-ER, but not for ER, which has implications for trial design.

328. National Expertise Group to Improve Management of Complex Encephalitis Cases

Background

Incidence of infectious encephalitis in France is evaluated to be 0.5 to 1/100,000 inhabitants. That means encephalitis are rare infections, and not all physicians do not have expertise about this disease. In case of complex presentations, they may benefit from advices and guidance from a multidisciplinary group. The French infectious diseases society implemented a group of expertise in 2016 to address clinicians’ difficulties with complex cases in a timely manner.

Methods

Experts were delegated by scientific societies (Infectious Disease, Microbiology, Neurology, Intensive care and Public Health) with regards to their expertise in brain infections. Any physician facing difficulties to manage a patient presenting as a complex case can ask for advice, using a specific e-mail address (encephalite.spilf@infectiologie.com). They have to provide a detailed summary of the clinical case, together with all available biological and etiological results and, when possible, an access to brain images. The case file is then or circulated by mail or discussed in a conference call, within 48 hours. At the end of the discussion, a written answer is produced (detailed recommendations and justification). The traceability of the advice is kept by the French infectious diseases society for both teaching purposes and legal matters.

Results

So far we had to examine 32 cases, providing from various hospital in mainland France, French West Indies, and Polynesia: 15 from university hospital and 17 from nonuniversity hospitals. Questions (overlapping in some cases) were related to diagnosis procedure (12), to treatment (4), to interpretation of imaging (5), to management of failure (6), and interpretation of test results (10). Our answers were: investigation for autoimmune or inflammatory disease (15); investigation for tuberculosis and/or treatment (14); investigation for tumour (3); complementary tests for an unusual pathogen (10). Pertinence of the advices was adapted in 20 cases (30 evaluated).

Conclusion

Such a group seems to be useful, and the organization at a national-level works. It is also the opportunity to extend our network in the field of neurological infections, and to use the submitted cases as education material for young ID fellows.

Disclosures

All authors: No reported disclosures.

Neurological Presentation of Zika Virus Infection Beyond the Perinatal Period

PURPOSE OF REVIEW

Our purpose was to summarize the current knowledge about the neurological presentation of Zika virus infection after the perinatal period. Other Flaviviruses infections, such as West Nile virus (WNV) or Japanese encephalitis virus (JEV), can result in neuro-invasive disease such as myelitis, encephalitis, or meningitis. We aimed at describing the specificities of ZV neurological infection.

RECENT FINDINGS

The recent outbreaks demonstrated clearly the neurotropism of ZV. However, by contrast with other Flaviviruses, the most frequent neurological presentation of ZV infection beyond the perinatal period was Guillain-Barré syndrome, especially the demyelination form of GBS. Encephalitis and myelitis seem to occur less frequently after ZV infection than after WNV or JEV infection. The pathophysiology of neurological ZV infections is still poorly understood and no specific treatment is available. Moreover, no data is available about long-term persisting symptoms and possible impairment of patients after the acute clinical episode.

JC virus granule cell neuronopathy: A cause of infectious cerebellar degeneration

JC virus (JCV) infection of glial cells can lead to progressive multifocal leukoencephalopathy (PML) in immunocompromised patients. A newly described phenotype of the infection is infection of neurons. This distinct clinical and radiological syndrome is named JCV granule cell neuronopathy, characterized by exclusive or predominant cerebellar atrophy. We report the clinical and radiological longitudinal findings of 5 HIV-infected patients referred to us between September 2004 and November 2011 who exhibited JCV granule cell neuronopathy (4 probable cases and 1 possible). The association of immunocompromised status, progressive cerebellar syndrome, MRI abnormalities with cortical cerebellar atrophy and cerebrospinal fluid positive for JCV on PCR allowed for a highly probable diagnosis. The reversal of the immunocompromised status is the only way to stop the disease evolution. Motor functioning can remain impaired, but the illness itself, unlike progressive multifocal leukoencephalopathy, does not seem to threaten life.

The spectrum of renal involvement in patients with inflammatory myopathies

Data regarding the incidence and outcome of renal involvement in patients with inflammatory myopathies (IM) remain scarce. We assessed the incidence and causes of acute kidney injury (AKI) and chronic kidney disease (CKD) in 150 patients with dermatomyositis, polymyositis, and antisynthetase syndrome followed in 3 French referral centers. Renal involvement occurred in 35 (23.3%) patients: AKI in 16 (10.7%), and CKD in 31 (20.7%) patients. The main cause of AKI was drug or myoglobinuria-induced acute tubular necrosis. Male sex, cardiovascular risk factors, cardiac involvement, and initial proteinuria >0.3 g/d were associated with the occurrence of AKI. The outcome of patients with AKI was poor: 13 (81%) progressed to CKD and 2 (12.5%) reached end-stage renal disease. In multivariate survival analysis, age at IM onset, male sex, a history of cardiovascular events, and a previous episode of AKI were associated with the risk of CKD. We also identified 14 IM patients who underwent a kidney biopsy in 10 nephrology centers. Renal pathology disclosed a wide range of renal disorders, mainly immune-complex glomerulonephritis. We identified in 5 patients a peculiar pattern of severe acute renal vascular damage consisting mainly of edematous thickening of the intima of arterioles. We found that AKI and CKD are frequent in patients with IM. Prevention of AKI is crucial in these patients, as AKI is a major contributor to their relatively high risk of CKD. A peculiar pattern of acute vascular damage is part of the spectrum of renal diseases associated with IM.

Central nervous system involvement in Whipple disease: clinical study of 18 patients and long-term follow-up

Whipple disease (WD) is a rare multisystemic infection with a protean clinical presentation. The central nervous system (CNS) is involved in 3 situations: CNS involvement in classic WD, CNS relapse in previously treated WD, and isolated CNS infection. We retrospectively analyzed clinical features, diagnostic workup, brain imaging, cerebrospinal fluid (CSF) study, treatment, and follow-up data in 18 patients with WD and CNS infection. Ten men and 8 women were included with a median age at diagnosis of 47 years (range, 30-56 yr). The median follow-up duration was 6 years (range, 1-19 yr). As categorized in the 3 subgroups, 11 patients had classic WD with CNS involvement, 4 had an isolated CNS infection, and 3 had a neurologic relapse of previously treated WD. CNS involvement occurred during prolonged trimethoprim-sulfamethoxazole (TMP-SMX) treatment in 1 patient with classic WD. The neurologic symptoms were various and always intermingled, as follows: confusion or coma (17%) related to meningo-encephalitis or status epilepticus; delirium (17%); cognitive impairment (61%) including memory loss and attention defects or typical frontal lobe syndrome; hypersomnia (17%); abnormal movements (myoclonus, choreiform movements, oculomasticatory myorhythmia) (39%); cerebellar ataxia (11%); upper motor neuron (44%) or extrapyramidal symptoms (33%); and ophthalmoplegia (17%) in conjunction or not with progressive supranuclear palsy. No specific pattern was correlated with any subgroup. Brain magnetic resonance imaging (MRI) revealed a unique focal lesion (35%), mostly as a tumorlike brain lesion, or multifocal lesions (23%) involving the medial temporal lobe, midbrain, hypothalamus, and thalamus. Periventricular diffuse leukopathy (6%), diffuse cortical atrophy (18%), and pachymeningitis (12%) were observed. The spinal cord was involved in 2 cases. MRI showed ischemic sequelae at diagnosis or during follow-up in 4 patients. Brain MRI was normal despite neurologic symptoms in 3 cases. CSF cytology was normal in 62% of patients, whereas Tropheryma whipplei polymerase chain reaction (PCR) analysis was positive in 92% of cases with tested CSF. Periodic acid-Schiff (PAS)-positive cells were identified in cerebral biopsies of 4 patients. All patients were treated with antimicrobial therapy for a mean duration of 2 years (range, 1-7 yr) with either oral monotherapy (TMP-SMX, doxycycline, third-generation cephalosporins) or a combination of antibiotics that sometimes followed parenteral treatment with beta-lactams and aminoglycosides. Eight patients also received hydroxychloroquine. At the end of follow-up, the clinical outcome was favorable in 14 patients (78%), with mild to moderate sequelae in 9. Thirteen patients (72%) had stopped treatment for an average time of 4 years (range, 0.7-14 yr). Four patients had clinical worsening despite antimicrobial therapy; 2 of those died following diffuse encephalitis (n = 1) and lung infection (n = 1). In conclusion, the neurologic manifestations of WD are diverse and may mimic almost any neurologic condition. Brain involvement may occur during or after TMP-SMX treatment. CSF T. whipplei PCR analysis is a major tool for diagnosis and may be positive in the absence of meningitis. Immune reconstitution syndrome may occur in the early months of treatment. Late prognosis may be better than previously reported, as a consequence of earlier diagnosis and a better use of antimicrobial therapy, including hydroxychloroquine and doxycycline combination.

FXTAS: new insights and the need for revised diagnostic criteria

OBJECTIVE

Fragile X-associated tremor ataxia syndrome (FXTAS) is defined by FMR1 premutation, cerebellar ataxia, intentional tremor, and middle cerebellar peduncle (MCP) hyperintensities. We delineate the clinical, neurophysiologic, and morphologic characteristics of FXTAS.

METHODS

Clinical, morphologic (brain MRI, (123)I-ioflupane SPECT), and neurophysiologic (tremor recording, nerve conduction studies) study in 22 patients with FXTAS, including 4 women.

RESULTS

A total of 43% of patients had no family history of fragile X syndrome (FXS), which contrasts with previous FXTAS series. A total of 86% of patients had tremor and 81% peripheral neuropathy. We identified 3 electroclinical tremor patterns: essential-like (35%), cerebellar (29%), and parkinsonian (12%). Two electrophysiologic patterns evocative of non-length-dependent (56%) and length-dependent sensory neuropathy (25%) were identified. Corpus callosum splenium (CCS) hyperintensity was as frequent (68%) as MCP hyperintensities (64%). Sixty percent of patients had parkinsonism and 47% abnormal (123)I-ioflupane SPECT. Unified Parkinson's Disease Rating Scale motor score was correlated to abnormal (123)I-ioflupane SPECT (p = 0.02) and to CGG repeat number (p = 0.0004). Scale for the assessment and rating of ataxia correlated with dentate nuclei hyperintensities (p = 0.03) and CCS hyperintensity was a marker of severe disease progression (p = 0.04).

CONCLUSIONS

We recommend to include in the FXTAS testing guidelines both CCS hyperintensity and peripheral neuropathy and to consider them as new major radiologic and minor clinical criterion, respectively, for the diagnosis of FXTAS. FXTAS should also be considered in women or when tremor, MCP hyperintensities, or family history of FXS are lacking. Our study broadens the spectrum of tremor, peripheral neuropathy, and MRI abnormalities in FXTAS, hence revealing the need for revised criteria.

Outcome of and prognostic factors for herpes simplex encephalitis in adult patients: results of a multicenter study

Management of herpes simplex encephalitis (HSE) has been considerably improved by the availability of acyclovir therapy and rapid polymerase chain reaction (PCR)-based diagnostic assays. Prognostic factors for this rare affliction are, however, misestimated. We conducted a large retrospective multicenter study that included 93 adult patients in whom HSE was diagnosed by PCR from 1991 through 1998 and who were treated with intravenous acyclovir. Among the 85 patients assessed at 6 months, 30 (35%) had a poor outcome, which led to death in 13 patients (15%) and severe disability in 17 (20%). The outcome was favorable for 55 patients (65%). A multivariate analysis identified 2 factors that were found to be independently associated with poor outcome: a Simplified Acute Physiology Score II >/=27 at admission and a delay of >2 days between admission to the hospital and initiation of acyclovir therapy. Early administration of antiviral therapy is the only parameter that can be modified to improve the prognosis of patients with HSE.

Different strategies of modulation can be operative during hypnotic analgesia: a neurophysiological study

Nociceptive electrical stimuli were applied to the sural nerve during hypnotically-suggested analgesia in the left lower limb of 18 highly susceptible subjects. During this procedure, the verbally reported pain threshold, the nociceptive flexion (RIII) reflex and late somatosensory evoked potentials were investigated in parallel with autonomic responses and the spontaneous electroencephalogram (EEG). The hypnotic suggestion of analgesia induced a significant increase in pain threshold in all the selected subjects. All the subjects showed large changes (i.e., by 20% or more) in the amplitudes of their RIII reflexes during hypnotic analgesia by comparison with control conditions. Although the extent of the increase in pain threshold was similar in all the subjects, two distinct patterns of modulation of the RIII reflex were observed during the hypnotic analgesia: in 11 subjects (subgroup 1), a strong inhibition of the reflex was observed whereas in the other seven subjects (subgroup 2) there was a strong facilitation of the reflex. All the subjects in both subgroups displayed similar decreases in the amplitude of late somatosensory evoked cerebral potentials during the hypnotic analgesia. No modification in the autonomic parameters or the EEG was observed. These data suggest that different strategies of modulation can be operative during effective hypnotic analgesia and that these are subject-dependent. Although all subjects may shift their attention away from the painful stimulus (which could explain the decrease of the late somatosensory evoked potentials), some of them inhibit their motor reaction to the stimulus at the spinal level, while in others, in contrast, this reaction is facilitated.

Morphine blocks descending pain inhibitory controls in humans

In man, heterotopic painful thermal conditioning stimuli induce parallel decreases in the spinal nociceptive flexion (RIII) reflex and the concurrent sensation of pain elicited by electrical stimulation of the sural nerve at the ankle. Such phenomena may be related to the diffuse noxious inhibitory controls (DNIC) which were initially described in the rat and subsequently documented in humans. In 9 subjects in the present study, a 2 min application of a moderately noxious temperature (46 degrees C) to the contralateral hand strongly depressed the RIII reflex elicited in the biceps femoris muscle by electrical stimulation of the sural nerve at 1.2 times the reflex threshold. These depressive effects were maximal during the second min of the conditioning period, showing a 80% inhibition of the RIII reflex which gradually recovered to its baseline value 7 min after the end of the conditioning period. Such inhibitory effects were completely blocked 15-26 min after administration of a low dose of morphine hydrochloride (0.05 mg/kg, i.v.). The lifting of the inhibitions was compatible with an action at the opioid receptors since the inhibitions were re-observed 5-16 min after naloxone injection (0.006 mg/kg, i.v.). During all the experimental sessions, heart and respiratory rates remained stable at their control levels. Since it has been shown previously that such a dose of morphine could not have a direct effect within the spinal cord (Willer 1985), it is concluded that this opiate blocks, in a naloxone-reversible fashion, those bulbo-spinal controls which are triggered by heterotopic nociceptive events. Possible implications for hypoalgesia based on the principles of counter-irritation are discussed.

Central analgesic effect of ketoprofen in humans: electrophysiological evidence for a supraspinal mechanism in a double-blind and cross-over study

The aims of this study were: (1) to test the hypothesis of a central analgesic effect of the aspirin-like drug ketoprofen and (2) to attempt to differentiate between a spinal and a supraspinal mechanism in this possible central action. The threshold of the nociceptive flexion reflex from the biceps femoris muscle elicited by sural nerve stimulation was studied before and after a double-blind, cross-over and randomized intravenous injection of ketoprofen (100 mg in 5 ml saline) and saline (5 ml) in 2 groups of volunteers. The first one was composed of 10 normal subjects while the second consisted of 8 paraplegic patients with complete spinal section of traumatic origin. In normal subjects, ketoprofen injection resulted in a rapid and significant increase (+68%) of the threshold of the nociceptive reflex, while saline injection produced a slow increase of only 17% of this threshold. In contrast, in paraplegic patients, neither ketoprofen nor saline produced any significant change in the nociceptive reflex threshold. A supraspinal involvement in the central analgesic effect of this drug is discussed.

Low dose epidural morphine does not affect non-nociceptive spinal reflexes in patients with postoperative pain

In order to determine the selectivity of the antinociceptive effect of epidural morphine, the electrophysiological features of a monosynaptic reflex were investigated before and after epidural morphine (2-3 mg) required for pain relief, in 4 patients suffering from postoperative pain. The reflex tested was the H reflex from the soleus muscle. Not only the classical Hmax/Mmax ratio, but also the threshold and the slope of the rising phase of the recruitment curve of H and M responses were analyzed. It was found that epidural morphine did not change significantly any of these parameters, at least during the 60 min post-injection period. By contrast, as usually observed clinically, epidural morphine produced an onset of pain relief by the 25th-30th min following injection. These data support the hypothesis that epidural morphine produced a 'selective spinal analgesia in man.'

Brain evoked potentials to noxious sural nerve stimulation in sciatalgic patients

In sciatalgic patients and before any treatment, the goal of this work was to compare the amplitude of the late component (N150-P220) of the brain evoked potential (BEP) between resting pain-free conditions and a neurological induced pain produced by the Lasègue manoeuvre. The study was carried out with 8 inpatients affected with a unilateral sciatica resulting from an X-ray identified dorsal root compression from discal origin. The sural nerve was electrically stimulated at the ankle level while BEPs were recorded monopolarly from the vertex. The stimulus intensity eliciting a liminal nociceptive reflex response in a knee-flexor muscle associated with a liminal pain was selected for this study. Both normal and affected side were alternatively stimulated during several conditions of controls and of Lasègue's manoeuvres performed on the normal and on the affected side. Results show that the Lasègue manoeuvre performed on the affected side induced a significant increase in the amplitude of N150-P220; performed on the normal side, this same manoeuvre resulted in a significant decrease of the N150-P220 amplitude. These variations were observed whatever was the side (normal or affected) under sural nerve stimulation. The possible neural mechanisms of these changes and clinical implications of these data are then discussed.