Changes in electrophysiological findings suggestive of demyelination following Guillain-Barré syndrome: A retrospective study.

INTRODUCTION/AIMS: Acute inflammatory demyelinating polyradiculoneuropathy (AIDP) is the most common form of Guillain-Barré syndrome (GBS) in Western countries. However, electrophysiological descriptions of changes in abnormalities suggestive of demyelination after an AIDP episode are rare. We aimed to describe the clinical and electrophysiological features of AIDP patients after the acute episode, to investigate changes in abnormalities suggestive of demyelination and to compare with electrophysiological features of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS: We reviewed the clinical and electrophysiological characteristics of 61 patients followed at regular intervals after the AIDP episode. RESULTS: We detected early electrophysiological abnormalities from the first nerve conduction studies (NCS) performed before 3 wk. Abnormalities suggestive of demyelination worsened on subsequent examinations. This worsening continued after more than 3 mo of follow-up for some parameters. We also found the persistence of abnormalities suggestive of demyelination for long periods after the acute episode, beyond 18 mo of follow-up, despite clinical improvement in most patients. DISCUSSION: In AIDP, NCS findings continue to worsen several weeks or even months after the onset of symptoms, and "CIDP-like" abnormalities suggestive of demyelination may persist for a long period of time, in contrast to the existing literature and the usually favorable clinical course. Thus, the discovery of conduction abnormalities on NCS performed long after an AIDP should always be interpreted according to the clinical context and not systematically lead to a diagnosis of CIDP.

Phrenic nerve conduction study to diagnose unilateral diaphragmatic paralysis.

BACKGROUND: Unilateral diaphragmatic paralysis (UDP) has major clinical and etiological implications and, therefore, is important to diagnose. Lung function tests and invasive transdiaphragmatic pressure (Pdi) measurements are widely used to this end but, contrary to phrenic nerve conduction study (NCS), they require volitional maneuvers and/or may be poorly tolerated by patients. The purpose of this study was to compare the diagnostic accuracy of Pdi and phrenic NCS for UDP. METHODS: We retrospectively reviewed 28 patients with suspected UDP. The diagnosis established during a multidisciplinary meeting was the reference standard. RESULTS: Phrenic NCS correlated well with Pdi (r = 0.82, P < .005), and the two tests showed good agreement (κ = 0.82, P < .005). Phrenic NCS and Pdi measurements both had 95% sensitivity, 87.5% specificity, 95% positive predictive, and 87.5% negative predictive values. CONCLUSIONS: Both tests were highly sensitive and specific. Phrenic NCS measurement is a simple, reproducible, noninvasive method whose results correlate well with Pdi and provide insight into the UDP mechanism. In the most difficult cases, combining lung function tests, respiratory muscle assessments, and phrenic NCS can help to establish the diagnosis.

Early Standard Electroencephalogram Abnormalities Predict Mortality in Septic Intensive Care Unit Patients.

INTRODUCTION: Sepsis is associated with increased mortality, delirium and long-term cognitive impairment in intensive care unit (ICU) patients. Electroencephalogram (EEG) abnormalities occurring at the acute stage of sepsis may correlate with severity of brain dysfunction. Predictive value of early standard EEG abnormalities for mortality in ICU septic patients remains to be assessed. METHODS: In this prospective, single center, observational study, standard EEG was performed, analyzed and classified according to both Synek and Young EEG scales, in consecutive patients acutely admitted in ICU for sepsis. Delirium, coma and the level of sedation were assessed at the time of EEG recording; and duration of sedation, occurrence of in-ICU delirium or death were assessed during follow-up. Adjusted analyses were carried out using multiple logistic regression. RESULTS: One hundred ten patients were included, mean age 63.8 (±18.1) years, median SAPS-II score 38 (29-55). At the time of EEG recording, 46 patients (42%) were sedated and 22 (20%) suffered from delirium. Overall, 54 patients (49%) developed delirium, of which 32 (29%) in the days after EEG recording. 23 (21%) patients died in the ICU. Absence of EEG reactivity was observed in 27 patients (25%), periodic discharges (PDs) in 21 (19%) and electrographic seizures (ESZ) in 17 (15%). ICU mortality was independently associated with a delta-predominant background (OR: 3.36; 95% CI [1.08 to 10.4]), absence of EEG reactivity (OR: 4.44; 95% CI [1.37-14.3], PDs (OR: 3.24; 95% CI [1.03 to 10.2]), Synek grade ≥ 3 (OR: 5.35; 95% CI [1.66-17.2]) and Young grade > 1 (OR: 3.44; 95% CI [1.09-10.8]) after adjustment to Simplified Acute Physiology Score (SAPS-II) at admission and level of sedation. Delirium at the time of EEG was associated with ESZ in non-sedated patients (32% vs 10%, p = 0.037); with Synek grade ≥ 3 (36% vs 7%, p< 0.05) and Young grade > 1 (36% vs 17%, p< 0.001). Occurrence of delirium in the days after EEG was associated with a delta-predominant background (48% vs 15%, p = 0.001); absence of reactivity (39% vs 10%, p = 0.003), Synek grade ≥ 3 (42% vs 17%, p = 0.001) and Young grade >1 (58% vs 17%, p = 0.0001). CONCLUSIONS: In this prospective cohort of 110 septic ICU patients, early standard EEG was significantly disturbed. Absence of EEG reactivity, a delta-predominant background, PDs, Synek grade ≥ 3 and Young grade > 1 at day 1 to 3 following admission were independent predictors of ICU mortality and were associated with occurence of delirium. ESZ and PDs, found in about 20% of our patients. Their prevalence could have been higher, with a still higher predictive value, if they had been diagnosed more thoroughly using continuous EEG.

Single-fiber electromyography analysis of botulinum toxin diffusion in patients with fatigue and pseudobotulism.

OBJECTIVE: To characterize electromyographic abnormalities according to symptoms (asymptomatic, fatigue, pseudobotulism) reported 1 month after botulinum toxin injection. DESIGN: Retrospective, single-center study comparing single-fiber electromyography (SFEMG) in the extensor digitorum communis (EDC) or orbicularis oculi (OO) muscles. SETTING: Hospital. PARTICIPANTS: Four groups of adults treated for spasticity or neurologic bladder hyperactivity (N=55): control group (asymptomatic patients: n=17), fatigue group (unusual fatigue with no weakness: n=15), pseudobotulism group (muscle weakness and/or visual disturbance: n=20), and botulism group (from intensive care unit of the same hospital: n=3). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Mean jitter, percentage of pathologic fibers, and percentage of blocked fibers were compared between groups. RESULTS: SFEMG was abnormal for 17.6% of control patients and 75% of patients in the pseudobotulism group. There were no differences between the control and fatigue groups. Mean jitter, percentage of pathologic fibers, and percentage of blocked fibers of the EDC muscle were significantly higher in the pseudobotulism group than in the fatigue and control groups. There were no differences between groups for the OO muscle. The SFEMG results in the botulism group were qualitatively similar to those of the pseudobotulism group. CONCLUSIONS: SFEMG of the EDC muscle confirmed diffusion of the toxin into muscles distant from the injection site in the pseudobotulism group. SFEMG in the OO muscle is not useful for the diagnosis of diffusion. No major signs of diffusion of botulinum toxin type A were found away from the injection site in patients with fatigue but no motor weakness. Such fatigue may be related to other mechanisms.

Sciatic nerve compression by neurogenic heterotopic ossification: use of CT to determine surgical indications.

OBJECTIVE: To describe the characteristics of neurogenic heterotopic ossification (NHO) based on clinical tests, electroneuromyography (ENMG) and CT in a database of patients with lesions of the central nervous system who required sciatic nerve neurolysis along with posterior hip NHO resection, and to determine the respective roles of ENMG and CT in the management of posterior hip NHOs in patients who are unable to communicate or express pain. METHODS: The consistency of the ENMG results with clinical findings, CT results and macroscopic signs of lesions was retrospectively assessed after sciatic nerve neurolysis and ablation of 55 posterior hip NHOs. RESULTS: Sciatic nerve neurolysis was necessary in 55 cases (47.4%; 55 out of 116). CT showed contact of the NHO with the nerve in all cases: 5 in contact with no deflection, 3 in contact with deflection, 21 moulded into a gutter and 26 entrapped in the NHO. There were clinical signs of sciatic nerve lesion in 21.8% of cases (12 out of 55). ENMG showed signs of sciatic nerve lesions in only 55.6% (10 out of 18), only 4 of whom presented with clinical signs of a nerve lesion. No significant relationship was found between clinical symptoms and ENMG findings of sciatic nerve compression (n = 13, p = 0.77). CONCLUSION: Nerve compression by NHO is likely an underdiagnosed condition, particularly in patients who are unable to communicate. Diagnosis of sciatic compression by NHO should be based on regular clinical examinations and CT. ENMG is not sufficiently sensitive to be used alone for surgical decision-making.

Electrophysiological diagnosis of Guillain-Barré syndrome subtype: could a single study suffice?

BACKGROUND: Serial electrophysiology has been suggested as essential for accurate diagnosis in Guillain-Barré syndrome (GBS). However, whether more adapted electrophysiological criteria may allow a single study to be sufficient is unknown. METHODS: We retrospectively reviewed records of 365 consecutive patients with GBS from Birmingham, U.K., and Garches, France, admitted between 1998 and 2013. Electrophysiology was analysed using existing criteria as well as a set of modified criteria, developed using sensitive and specific cut-off values for demyelination and incorporating new knowledge on electrophysiology of axonal GBS. We compared diagnostic rates and classification changes using modified criteria with published literature relating to serial studies. RESULTS: With existing criteria, we found similar proportions of acute inflammatory demyelinating polyradiculoneuropathy (AIDP) (71.5% vs. 72%; p=1), axonal GBS (17.5% vs. 14.7%; p=0.62) and equivocal forms (9.9% vs. 13.3%; p=0.41) to the previous studies considered. With modified criteria, we identified comparable rates of AIDP (56.2% vs. 58.7%; p=0.70), axonal GBS (35.1% vs. 36%; p=0.89) and equivocal forms (7.7% vs. 5.3%; p=0.63) with a single nerve conduction study as compared with when serial electrophysiology was used in previous analyses. We observed an identical diagnostic shift from AIDP to axonal GBS with modified criteria as that described with serial studies (21.5% vs. 18.5%; p=0.72). Classification changes with modified criteria correlated significantly with performing of electrophysiology ≤7 days after symptom onset (p=0.045), indicating their greater usefulness in earlier disease stages. CONCLUSIONS: A single electrophysiological study may suffice to establish the ultimate electrodiagnosis of GBS subtype if the proposed modified electrodiagnostic criteria are used.

Whole-body muscle MRI to detect myopathies in non-extrapyramidal bent spine syndrome.

OBJECTIVE: Bent spine syndrome (BSS), defined as an abnormal forward flexion of the trunk resolving in supine position, is usually related to parkinsonism, but can also be encountered in myopathies. This study evaluates whole-body muscle MRI (WB-mMRI) as a tool for detecting underlying myopathy in non-extrapyramidal BSS. MATERIALS AND METHODS: Forty-three patients (90 % women; 53-86 years old) with a non-extrapyramidal BSS were prospectively included. All underwent a 1.5-T WB-mMRI and a nerve conduction study. Muscle biopsy was performed if a myopathy could not be eliminated based on clinical examination and all tests. Systematic MRI interpretation focused on peripheral and axial muscle injury; spinal posture and incidental findings were also reported. RESULTS: WB-mMRI was completed for all patients, with 13 muscle biopsies ultimately needed and myopathy revealed as the final etiological diagnosis in five cases (12 %). All biopsy-proven myopathies were detected by the WB-mMRI. Relevant incidental MRI findings were made in seven patients. CONCLUSIONS: This study supports WB-mMRI as a sensitive and feasible tool for detecting myopathy in BSS patients. Associated with electroneuromyography, it can better indicate when a muscle biopsy is needed and guide it when required. Rigorous radiological interpretation is mandatory, so as not to miss incidental findings of clinical consequence.

Optoelectronic plethysmography as an alternative method for the diagnosis of unilateral diaphragmatic weakness.

BACKGROUND: The objective was to determine whether optoelectronic plethysmography (OEP) can detect asymmetric ventilation related to unilateral or asymmetric diaphragmatic weakness, suggesting usefulness as a diagnostic tool. METHODS: Thirteen patients with suspected asymmetric diaphragmatic weakness based on dyspnea and hemidiaphragm elevation on the chest radiograph were studied as well as three patients with maltase acid deficiency (a cause of symmetrical diaphragmatic weakness). The transdiaphragmatic pressure response to unilateral magnetic stimulation (lateral twitch transdiaphragmatic pressure [latPdiTw]) and the diaphragm compound muscle action potentials (CMAPs) elicited by transcutaneous electrical stimulation of each phrenic nerve as well as OEP were performed. RESULTS: The CMAPs and latPdiTw showed unilateral or predominantly unilateral diaphragmatic weakness in nine of the 13 patients. By OEP, the affected side of the thorax and abdomen contributed < 45% of the inspiratory capacity in each of these nine patients, whereas no asymmetry was noted in the other four patients or in the three patients with maltase acid deficiency. All patients preferred OEP over CMAP or latPdiTw. CONCLUSIONS: OEP detected asymmetric ventilation in all patients diagnosed with unilateral diaphragm weakness and in no patients without this diagnosis. Thus, OEP is an effective noninvasive alternative that is preferred by the patients over CMAP response and latPdiTw.

Relevance of anxiety in clinical practice of Guillain-Barre syndrome: a cohort study.

OBJECTIVES: Illness is often associated with anxiety, but few data exist about the prognostic significance of this phenomenon. To address this issue, we assessed whether patient anxiety is associated with subsequent need for intubation in Guillain-Barré syndrome (GBS). DESIGN: Incident case-cohort study. SETTING: Acute secondary care in a teaching hospital (France) from 2006 to 2010. PARTICIPANTS: 110 adult GBS patients. Either language barrier or cognitive decline that precluded understanding was considered as exclusion criteria. PRIMARY OUTCOME: Acute respiratory failure. INTERVENTIONS: At admission, anxiety and clinical factors (including known predictors of respiratory failure: delay between GBS onset and admission, inability to lift head, vital capacity (VC)) were assessed and related to subsequent need for mechanical ventilation (MV). Anxiety was assessed using a Visual Analogical Scale (VAS), the State Anxiety Inventory form Y1 (STAI-Y1) score and a novel-specific questionnaire, evaluating fears potentially triggered by GBS. Patients were asked to choose which they found most stressful from weakness, pain, breathlessness and uncertainty. RESULTS: 23 (22%) were subsequently ventilated. Mean STAI-Y1 was 47.2 (range 22-77) and anxiety VAS 5.2 (range 0-10). STAI was above 60/80 in 22 (21%) patients and anxiety VAS above 7/10 in 28 (27%) patients. Fear of remaining paralysed, uncertainty as to how the disease would progress and fear of intubation were the most stressful. Factors significantly associated with anxiety were weakness and bulbar dysfunction. STAI-Y1 was higher and uncertainty more frequent in subsequently ventilated patients, who had shorter onset-admission delay and greater weakness but not a lower VC. Uncertainty was independently associated with subsequent MV. CONCLUSIONS: Early management of patients with GBS should evaluate anxiety and assess its causes both to adjust psychological support and to anticipate subsequent deterioration.

Pilot study evaluating the safety of intradetrusor injections of botulinum toxin type A: investigation of generalized spread using single-fiber EMG.

AIMS: Intradetrusor botulinum toxin type-A injections are a novel therapy for treatment of neurogenic overactive bladder resistant to parasympatholytic treatment. In rare cases, however, it may be associated with generalized muscle weakness. Single-fiber electromyographic (SFEMG) analysis of neuromuscular jitter (NJ) was used to study OnabotulinumtoxinA (BOTOX®) migration to striated muscle. METHODS: This study comprised a prospective, single-center investigation of 21 spinal cord injured patients receiving intradetrusor OnabotulinumtoxinA. Clinical tolerance was assessed through muscle testing and para-clinical tolerance by systematic analysis of NJ in muscles distant from the bladder. RESULTS: Twenty-one patients (13 males, 8 females) received one intradetrusor injection of 300 U OnabotulinumtoxinA. Mean age was 42.1 ± 14.4 and mean number of injections prior to study inclusion was 2.6 ± 1.7. Clinical and para-clinical assessments were performed on average 26 days ± 8 days post-OnabotulinumtoxinA injection. Seven patients had abnormal NJ results on SFEMG, but no patient had evidence of blocking. Four patients complained of tiredness (one with NJ abnormalities). CONCLUSIONS: Patients showed good tolerance to intradetrusor OnabotulinumtoxinA injections. Tiredness was not associated with generalized muscle weakness since testing remained unchanged and NMJ was normal in three of four patients. NJ analysis was abnormal in 7 of 21 patients, but this was not considered serious and there was no evidence of muscle fiber block. These results support the safety of bladder injections of OnabotulinumtoxinA and suggest that, although migration of OnabotulinumtoxinA to other muscle groups may impair NJ function in a minority of patients, this does not correlate with symptoms of tiredness or muscle weakness.

Guillain-Barré syndrome following primary cytomegalovirus infection: a prospective cohort study.

BACKGROUND: Little is known about the epidemiology and the prognostic factors of Guillain-Barré syndrome (GBS) following primary infection with cytomegalovirus (CMV-GBS). METHODS: We prospectively followed up 506 patients with cases of GBS who were admitted to our center from 1996 through 2006. We diagnosed 63 (12.4%) CMV-GBS cases by immunoglobulin (Ig) M detection and IgG avidity. Plasma CMV DNA was detected at hospital admission. Patient subgroups were compared using Fisher's exact test and the Wilcoxon rank-sum test. Temporal variations were analyzed with time series methods. RESULTS: Patients with CMV-GBS were mostly young (median age, 32 years; sex ratio, 0.85), but we also identified a subpopulation of patients consisting of women aged >50 years. Sensory defects (in 72% of cases) and facial palsy (49%) were frequent, and test results positive for CMV DNA in plasma at hospital admission (found in 62% of cases) tended to be associated with objective sensory defect (P=.052). The main factors associated with long-term neurological sequelae (21%) were older age (P<.001) and assisted ventilation during hospitalization (P=.005). The number of CMV-GBS cases decreased between 1996 and 2006 (P=.019) and displayed an annual periodicity between the months of July and October. The incidence of CMV-GBS was estimated to be between 0.6 and 2.2 cases per 1000 cases of primary CMV infection (versus 0.25 to 0.65 cases per 1000 cases of Campylobacter jejuni infection). CONCLUSIONS: This study provides new insights about the epidemiology of CMV-GBS and shows that the risk of developing GBS is similar following primary CMV infection or C. jejuni infection. Our results also suggest a direct or indirect involvement of viral replication in the neuropathological processes of CMV-GBS.

Acute urinary retention due to viral coinfections (HIV, HBV, VZV).

We report a case of acute urinary retention with meningoradiculoneuritis resulting from coinfection with varicella-zoster virus (VZV), HIV, and hepatitis B virus (HBV). The case is discussed in the context of other neurological syndromes associated with VZV and HIV infections, and of other viral causes of acute retention of urine.

Presence and severity of intensive care unit-acquired paresis at time of awakening are associated with increased intensive care unit and hospital mortality.

OBJECTIVES: To assess whether the presence and severity of intensive care unit-acquired paresis are associated with intensive care unit and in-hospital mortality. DESIGN: Prospective, observational study. SETTING: Two medical, one surgical, and one medico-surgical intensive care units in two university hospitals and one university-affiliated hospital. PATIENTS: A total of 115 consecutive patients were enrolled after > 7 days of mechanical ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The Medical Research Council score (from 0-60) was used to evaluate upper and lower limb strength at time of awakening, identified as the ability to follow five commands. Intensive care unit-acquired paresis was defined as a Medical Research Council score <48. Patients were followed-up until hospital discharge. The primary end point was hospital mortality. At awakening, median Medical Research Council score was 41 (interquartile range, 21-52), and 75 (65%) patients had intensive care unit-acquired paresis. Hospital non-survivors had a significantly lower Medical Research Council score at awakening (21 [11-43]) vs. 41 [28-53]; p = .008) and a significantly higher rate of intensive care unit-acquired paresis (85.1% vs. 58.4%; p = .02) compared to survivors. After multivariate risk adjustment, intensive care unit-acquired paresis was independently associated with higher hospital and intensive care unit mortality (odds ratio for hospital mortality, 2.02; 95% confidence interval, 1.03-8.03; p = .048). Each Medical Research Council point decrease was associated with a significantly higher hospital mortality (odds ratio, 1.03; 95% confidence interval, 1.01-1.05; p = .033). CONCLUSIONS: Both the presence and severity of intensive care unit-acquired paresis at the time of awakening are associated with increased intensive care unit and hospital mortality; the mechanisms underlying this association need further study.

Plasma cortisol levels in Guillain-Barré syndrome.

OBJECTIVE: To assess the relationship between plasma cortisol level and Guillain-Barré syndrome-related complications, notably respiratory failure. One third of patients with Guillain-Barré syndrome develop respiratory failure, which is predicted by few early indicators. Adrenal function has rarely been studied in Guillain-Barré syndrome. DESIGN: Prospective study. SETTING: Intensive care unit in a teaching hospital. PATIENTS: Patients with Guillain-Barré syndrome referred to our unit (n = 102). INTERVENTIONS: Plasma cortisol levels were measured before baseline and 60 mins after corticotrophin test in 93 patients with Guillain-Barré syndrome at admission, 16 (17%) of whom were ventilated within 24 hrs from admission, 17 (18%) ventilated after the 24th hr and 60 (65%) never ventilated. MEASUREMENTS AND MAIN RESULTS: Mean plasma cortisol levels at baseline and 60 mins after corticotrophin test were 22.9 +/- 11.3 ng/mL and 45.4 +/- 16.1 ng/mL. At baseline, the plasma cortisol levels were significantly higher in 17 (18%) patients, who developed respiratory failure at least 24 hrs later (28.5 +/- 12.1 ng/mL vs. 20.4 +/- 9.6 ng/mL; p = .003) and dysautonomia (33.1 +/- 14.3 ng/mL vs. 21.4 +/- 10.2 ng/mL, p = .003). When adjusting on only validated clinical predictors (i.e., delay between onset and admission <7 days, inability to lift head and vital capacity <60%), baseline cortisol level was the only independent risk factor for respiratory failure (odds ratio: 2.45 per 10 ng/mL [1.23-4.88 ng/mL], p = .01). Fifty-nine patients underwent electrophysiological testing. When adjusting on a validated electrophysiological model (i.e., peroneal proximal/distal compound muscle action potential ratio and vital capacity), baseline cortisol level remained an independent predictor (odds ratio: 2.50 per 10 ng/mL [1.14-5.51 ng/mL], p = .02). CONCLUSION: Measurement of baseline plasma cortisol levels can be helpful for early detection of patients with Guillain-Barré syndrome at risk for respiratory failure at least 24 hrs later.

Guillain-Barré syndrome and influenza virus infection.

BACKGROUND: In Western countries, the cause of 60% of all Guillain-Barré syndrome (GBS) cases remains unidentified. The number of cases of unidentified cause peaks in winter, and these cases are commonly preceded by respiratory tract infection or influenza-like illness. We investigated the triggering role of influenza virus infection. METHODS: Of 405 patients with GBS who were admitted to a French reference center during 1996-2004, 234 had cases caused by an unidentified agent. We used time-series methods to study the correlation between the monthly incidence of such cases and influenza-like illnesses reported by the Sentinelles surveillance network. We analyzed anti-influenza antibodies using complement fixation testing and hemagglutination-inhibition assays. We studied etiological subgroups using Wilcoxon and Fisher's exact tests. RESULTS: We found a positive association between the monthly incidence of GBS caused by an unidentified agent and reported influenza-like illnesses. Of 73 patients whose cases occurred during periods in which there was a possible link to influenza, 10 (13.7%) had serological evidence of recent influenza A, and 4 (5.5%) had serological evidence of influenza B. Eight of 10 influenza A-related cases occurred during "major" influenza seasons, and antibodies specific to the current epidemic strain were found in 9 cases. Most patients with influenza A-related cases were aged < 65 years, and none had antiganglioside antibodies. Influenza-related cases differed both from Campylobacter jejuni-related cases, with regard to the lack of need for mechanical ventilation (P = .014), and from the cases caused by an unidentified agent, with regard to the presence of preceding influenza-like illness or respiratory tract infection (P = .015) and longer time from the infectious event to GBS onset (P = .04). CONCLUSIONS: Influenza viruses are infrequent triggering agents of GBS but may play a significant role during major influenza outbreaks. Influenza-related GBS displays specific features and is not associated with antiganglioside antibody response, which suggests the presence of underlying immune mechanisms.

Undesirable distant effects following botulinum toxin type a injection.

OBJECTIVES: To study the incidence of clinical signs linked to botulinum toxin type A (BoNTA) spread from the injection site. METHODS: Single-center, retrospective, cohort study. All patients who received BoNTA injections for spasticity treatment were assessed 1 month postinjection. Adverse effects indicative of BoNTA treatment were systematically sought. Any patient with adverse effects possibly due to BoNTA spread underwent further clinical examination and single-fiber electromyography. One patient underwent neuromuscular biopsy. RESULTS: Between January and September 2005, 266 BoNTA injection sessions (187 patients) were performed (233 BOTOX, 33 Dysport). Five patients presented with clinical signs of toxin spread. Four of these underwent single-fiber electromyography, which showed increased jitter. Neuromuscular biopsy detected signs of recent denervation without signs of reinnervation. CONCLUSIONS: Diffusion diagnosis of BoNTA from the injection site depends on clinical, temporal, and electromyographic factors. Clinical expression of spread varies widely, with mechanisms remaining largely unknown, and further prospective, randomized clinical trials are required.

Critical illness neuromuscular syndromes.

Critical illness neuromyopathy (CINM) is suggested by bilateral diffuse weakness predominant in the proximal part of the limbs after improvement of the acute phase of critical illness. Although muscle and peripheral nerve are often involved in combination, muscle involvement alone is increasingly identified on electrophysiologic investigation, including direct muscle stimulation. CINM frequently involves the respiratory muscles and may result in delayed weaning and prolonged mechanical ventilation. Besides muscle immobilization and prolonged sepsis-induced multiorgan failure, which are risk factors for CINM, hyperglycemia and use of corticosteroids might have a deleterious effect on the neuromuscular system in critically ill patients, suggesting opportunities for preventive interventions.

Respiratory weakness is associated with limb weakness and delayed weaning in critical illness.

OBJECTIVE: Although critical illness neuromyopathy might interfere with weaning from mechanical ventilation, its respiratory component has not been investigated. We designed a study to assess the level of respiratory muscle weakness emerging during the intensive care unit stay in mechanically ventilated patients and to examine the correlation between respiratory and limb muscle strength and the specific contribution of respiratory weakness to delayed weaning. DESIGN: Prospective observational study. SETTING: Two medical, one surgical, and one medicosurgical intensive care units in two university hospitals and one university- affiliated hospital. PATIENTS: A total of 116 consecutive patients were enrolled after >or=7 days of mechanical ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Maximal inspiratory and expiratory pressures and vital capacity were measured via the tracheal tube on the first day of return to normal consciousness. Muscle strength was measured using the Medical Research Council score. After standardized weaning, successful extubation was defined as the day from which mechanical ventilatory support was no longer required within the next 15 days. The median value (interquartile range) of maximal inspiratory pressure was 30 (20-40) cm H2O, maximal expiratory pressure was 30 (20-50) cm H2O, and vital capacity was 11.1 (6.3-19.8) mL/kg. Maximal inspiratory pressure, maximal expiratory pressure, and vital capacity were significantly correlated with the Medical Research Council score. The median time (interquartile range) from awakening to successful extubation was 6 (1-17) days. Low maximal inspiratory pressure (hazard ratio, 1.86; 95% confidence interval, 1.07-3.23), maximal expiratory pressure (hazard ratio, 2.18; 95% confidence interval, 1.44-3.84), and Medical Research Council score (hazard ratio, 1.96; 95% confidence interval, 1.27-3.02) were independent predictors of delayed extubation. Septic shock before awakening was significantly associated with respiratory weakness (odds ratio, 3.17; 95% confidence interval, 1.17-8.58). CONCLUSIONS: Respiratory and limb muscle strength are both altered after 1 wk of mechanical ventilation. Respiratory muscle weakness is associated with delayed extubation and prolonged ventilation. In our study, septic shock is a contributor to respiratory weakness.

Critical illness neuromuscular syndromes.

Critical illness neuromyopathy (CINM) is the most common peripheral neuromuscular disorder encountered in the ICU. Bilateral diffuse weakness predominant in the proximal part of the limbs after improvement of the acute phase of the critical illness is highly suggestive of CINM. Although muscle and peripheral nerve often are involved in combination, muscle involvement alone increasingly is identified on electrophysiological investigation, including direct muscle stimulation. Respiratory muscles also are involved, and CINM may cause delayed weaning and prolonged MV. Besides muscle immobilization and prolonged sepsis-induced multiple organ failure, which are both strong contributors to CINM, hyperglycemia and use of corticosteroids also might have a deleterious effect on the neuromuscular system in critically ill patients.

Clinical and electrophysiological predictors of respiratory failure in Guillain-Barré syndrome: a prospective study.

BACKGROUND: Respiratory failure is the most serious short-term complication of Guillain-Barré syndrome and can require invasive mechanical ventilation in 20-30% of patients. We sought to identify clinical and electrophysiological predictors of respiratory failure in the disease. METHODS: We prospectively assessed electrophysiological data and clinical factors, including identified predictors of delay between disease onset and admission, inability to lift head, and vital capacity, in patients admitted with Guillain-Barré syndrome. We related these factors to subsequent need for ventilatory support. Neurophysiological findings were classified as demyelinating, axonal, equivocal, unexcitable, or normal. Predictive values of clinical and electrophysiological data were tested using classification trees to build up a predictive model. This model was initially built up in a two-third (fitting set) then validated in a one-third (validation set) of the total sample. The fitting and validation sets were randomly selected. We also assessed the predictive value of this model for disability at 6 months. FINDINGS: From 1998, to 2006, 154 patients with Guillain-Barré syndrome were included in the study and 34 (22%) were subsequently ventilated. Demyelinating Guillain-Barré syndrome was more common in patients who went on to be ventilated than in those who were not (85%vs 51%, p=0.0003). Vital capacity and the proximal/distal compound muscular amplitude potential (p/dCMAP) ratio of the common peroneal nerve were retained in the tree model, with a probability of needing ventilation of less than 2.5% in patients with a ratio of greater than 55.6% and a vital capacity more than 81% of predicted. A p/dCMAP ratio of the peroneal nerve less than 55.6% and age older than 40 years were retained as independent predictors of disability at 6 months. INTERPRETATION: Neurophysiological testing is helpful for assessing risk of respiratory failure, which is highest in patients with evidence of demyelination and very low in those without both 55.6% conduction block of the common peroneal nerve and a 20% reduction in vital capacity.