The neurological complications of sepsis

Double-filtration plasmapheresis for resolution of corticosteroid resistant adult onset Still's disease

A 45-year-old Japanese male was diagnosed with adult onset Still's disease (AOSD). High-dose corticosteroid initially resolved the illness; however, high fever, maculopalpular rashes, arthralgia, and acute pericarditis rapidly recurred, and were followed by a somnolent state without focal signs. A diagnosis of corticosteroid resistant, severe, recurrent AOSD was made, and double-filtration plasmapheresis (DFPP) was performed immediately. The somnolent state began to resolve during the first plasmapheresis procedure, and the other symptoms resolved shortly thereafter. DFPP theoretically removes monocyte-activating cytokines, such as monocyte colony-stimulating factor (M-CSF) from the circulation, and therefore may prove to be an effective treatment for corticosteroid resistant, rapidly developing cases of AOSD.

Interleukin-1beta enhances GABAA receptor cell-surface expression by a phosphatidylinositol 3-kinase/Akt pathway: relevance to sepsis-associated encephalopathy

Sepsis-associated encephalopathy (SAE) is a frequent but poorly understood neurological complication in sepsis that negatively influences survival. Here we present clinical and experimental evidence that this brain dysfunction may be related to altered neurotransmission produced by inflammatory mediators. Compared with septic patients, SAE patients had higher interleukin-1beta (IL-1beta) plasma levels; interestingly, these levels decreased once the encephalopathy was resolved. A putative IL-1beta effect on type A gamma-aminobutyric acid receptors (GABA(A)Rs), which mediate fast synaptic transmission in most cerebral inhibitory synapses in mammals, was investigated in cultured hippocampal neurons and in Xenopus oocytes expressing native or foreign rat brain GABA(A)Rs, respectively. Confocal images in both cell types revealed that IL-1beta increases recruitment of GABA(A)Rs to the cell surface. Moreover, brief applications of IL-1beta to voltage-clamped oocytes yielded a delayed potentiation of the GABA-elicited chloride currents (I(GABA)); this effect was suppressed by IL-1ra, the natural IL-1 receptor (IL-1RI) antagonist. Western blot analysis combined with I(GABA) recording and confocal images of GABA(A) Rs in oocytes showed that IL-1beta stimulates the IL-1RI-dependent phosphatidylinositol 3-kinase activation and the consequent facilitation of phospho-Akt-mediated insertion of GABA(A)Rs into the cell surface. The interruption of this signaling pathway by specific phosphatidylinositol 3-kinase or Akt inhibitors suppresses the cytokine-mediated effects on GABA(A)R, whereas activation of the conditionally active form of Akt1 (myr-Akt1.ER*) with 4-hydroxytamoxifen reproduces the effects. These findings point to a previously unrecognized signaling pathway that connects IL-1beta with increased "GABAergic tone." We propose that through this mechanism IL-1beta might alter synaptic strength at central GABAergic synapses and so contribute to the cognitive dysfunction observed in SAE.

Sleep in acute care units

Patients in the acute care units (ACU) are usually critically ill, making them more susceptible to the unfavorable atmosphere in the hospital. One of these unfavorable factors is sleep disruption and deprivation. Many factors may affect sleep in the ACU, including therapeutic interventions, diagnostic procedures, medications, the underlying disease process, and noise generated in the ACU environment. Many detrimental physiological effects can occur secondary to noise and sleep deprivation, including cardiovascular stimulation, increased gastric secretion, pituitary and adrenal stimulation, suppression of the immune system and wound healing, and possible contribution to delirium. Over the past few years, many studies have endeavored to objectively assess sleep in the ACUs, as well as the effect of mechanical ventilation and circadian rhythm changes critically ill patients. At this time, therefore, it is important to review published data regarding sleep in ACUs, in order to improve the knowledge and recognition of this problem by health care professionals. We have therefore reviewed the methods used to assess sleep in ACUs, factors that may affect sleep in the ACU environment, and the clinical implications of sleep disruption in the ACU.

Chronic neurocognitive effects of critical illness

PURPOSE OF REVIEW

Until relatively recently critical care practitioners have focused on survival of their patients and not long-term outcomes. An increasing body of research has examined patient outcomes beyond discharge from the intensive care unit and hospital. One area of focus is neurobehavioral outcomes including neurocognitive sequelae and neuropsychiatric disorders such as depression and anxiety. Cognitive functions are brain-based or mental activities that involve acquiring, storing, retrieving, and using information and include domains such as memory, attention, executive function, mental processing speed, spatial abilities, and general intelligence. It is known from other medical specialties that impaired cognitive function can have a broad, substantial, and long-lasting impact on a patient's life. This paper examines the current evidence for neurocognitive impairments in survivors of critical illness.

RECENT FINDINGS

Recent studies support the hypothesis that critical illness can lead to significant impairments in neurocognitive function. Current work indicates that the neurocognitive impairments can last for months or years after a patient arrives home and may have important consequences for quality of individual and family life and for ability to return to work as well as substantial economic costs. The mechanisms of neurocognitive impairments are not fully understood, but in acute respiratory distress syndrome hypoxemic burden appears important.

SUMMARY

Among the potential consequences of critical illness are now included neurocognitive impairments. Future research should include the search for strategies for the early identification of neurocognitive impairments, mechanisms of brain injury, and therapeutic modalities designed to prevent or decrease neurocognitive morbidity.

Intestinal Ischemia-Reperfusion Injury Does Not Lead to Acute Central Nervous System Damage

BACKGROUND

The detrimental effects of intestinal ischemia reperfusion (IIR) injury on secondary organs including the liver, lungs, heart, and kidney have been widely investigated in animal models. However, the effect of IIR on the central nervous system (CNS) is largely unknown. We investigated the effect of IIR on the CNS as it may be of clinical relevance to patients at high risk of neurological injury.

MATERIALS AND METHODS

Adult male rats underwent IIR (60 min superior mesenteric artery occlusion followed by 120 min reperfusion, n = 7) or sham operation (n = 6) under anesthesia. Following the procedure, the cerebral hemispheres were removed for histological assessment and measurement of N-acetyl-aspartate (NAA), a marker of neuronal damage, by HPLC. Blood was taken for determination of plasma S100B concentration, a measure of glial cell damage by ELISA. Data are median (range).

RESULTS

Cerebral tissue from all animals from both groups was macroscopically and microscopically normal with no evidence of inflammation. NAA in brain homogenate was similar in the IIR group (0.2 [0.1-0.32] nmol/mg protein) and sham-operated group (0.19 [0.12-0.34], P = 0.83). Plasma S100B levels were higher in the IIR group compared to sham-operated animals but this difference was not statistically significant (1.13 [0.24-7.26] versus 0.55 [0.23-2.84] mug/l, P = 0.18).

CONCLUSIONS

In this model, IIR injury did not produce histological CNS changes nor biochemical changes suggestive of neuronal damage. Further work is required to elucidate any functional effect of IIR injury on the CNS.

Neuromuscular manifestations of critical illness

Critical illness, more precisely defined as the systemic inflammatory response syndrome (SIRS), occurs in 20%-50% of patients who have been on mechanical ventilation for more than 1 week in an intensive care unit. Critical illness polyneuropathy (CIP) and myopathy (CIM), singly or in combination, occur commonly in these patients and present as limb weakness and difficulty in weaning from the ventilator. Critical illness myopathy can be subdivided into thick-filament (myosin) loss, cachectic myopathy, acute rhabdomyolysis, and acute necrotizing myopathy of intensive care. SIRS is the predominant underlying factor in CIP and is likely a factor in CIM even though the effects of neuromuscular blocking agents and steroids predominate in CIM. Identification and characterization of the polyneuropathy and myopathy depend upon neurological examination, electrophysiological studies, measurement of serum creatine kinase, and, if features suggest a myopathy, muscle biopsy. The information is valuable in deciding treatment and prognosis.

Acute quadriplegia complicating critical illness polyneuropathy in a patient with infective endocarditis: a case report

A 75-year-old woman with infective endocarditis developed critical illness polyneuropathy (CIP) with quadriplegia after cardiac surgery. The quadriplegia resolved gradually after aggressive treatment of the underlying infection and with rehabilitation. However, a MEDLINE search of the English-language literature failed to yield results matching quadriplegia and infective endocarditis. CIP is a complication of septic syndrome and sepsis. This complication has been largely unrecognized in intensive care units owing to difficulties in performing a clinical examination or electrophysiologic studies. Difficulty in weaning from the ventilator is an important early manifestation of CIP. Electroneuromyography (ENMG) should be routinely performed to establish the diagnosis. We suggest that any septic patients with unexplained muscle weakness, paralysis, or difficulty in weaning from the ventilator should be evaluated for CIP.

Septic shock

Septic shock, the most severe complication of sepsis, is a deadly disease. In recent years, exciting advances have been made in the understanding of its pathophysiology and treatment. Pathogens, via their microbial-associated molecular patterns, trigger sequential intracellular events in immune cells, epithelium, endothelium, and the neuroendocrine system. Proinflammatory mediators that contribute to eradication of invading microorganisms are produced, and anti-inflammatory mediators control this response. The inflammatory response leads to damage to host tissue, and the anti-inflammatory response causes leucocyte reprogramming and changes in immune status. The time-window for interventions is short, and treatment must promptly control the source of infection and restore haemodynamic homoeostasis. Further research is needed to establish which fluids and vasopressors are best. Some patients with septic shock might benefit from drugs such as corticosteroids or activated protein C. Other therapeutic strategies are under investigation, including those that target late proinflammatory mediators, endothelium, or the neuroendocrine system.

Effect of stress doses of hydrocortisone on S-100B vs. interleukin-8 and polymorphonuclear elastase levels in human septic shock

Stress doses of hydrocortisone are known to have immunomodulatory effects in patients with hyperdynamic septic shock. The prognosis correlates with the presence and severity of septic encephalopathy. However, neurological evaluation is influenced by the use of analgesia sedation during artificial ventilation. The objective of this study was to demonstrate the effect of stress doses of hydrocortisone during the initial phase of human septic shock on the serum values of the neurospecific protein S-100B in comparison to the inflammation markers interleukin (IL)-8 in serum and polymorphonuclear (PMN) elastase in plasma. A total of 24 consecutive patients, who met the American College of Chest Physicians/Society of Critical Care Medicine criteria for septic shock, were enrolled in this prospective, randomized, double-blind, single-center trial. The severity of illness at recruitment was graded using the Acute Physiology and Chronic Health Evaluation II and the Simplified Acute Physiology Score II scoring systems. Multi-organ dysfunction syndrome was described by the Sepsis-related Organ Failure Assessment (SOFA) score. All patients were prospectively randomized to receive either stress doses of hydrocortisone or placebo. Hydrocortisone was started in 12 patients with a loading dose of 100mg and followed by a continuous infusion of 0.18mg/kg/h for 6days. Median S-100B serum levels of the hydrocortisone group decreased from 0.32ng/mL at study entry to 0.07ng/mL 6days later without significant differences compared to the placebo group. Initial IL-8 serum levels were significantly higher in the hydrocortisone group up to 12h after study entry, and significantly decreased from 715 to 17pg/mL at the end of the observation period. Median PMN elastase plasma levels were not affected by hydrocortisone infusion. Patients with initial S-100B serum levels >0.50ng/mL revealed significantly higher SOFA scores up to 30h, IL-8 serum levels up to 12h, and PMN elastase plasma levels up to 36h after study entry than those patients with ≤0.50ng/mL. These effects were independent of the amount of fluid correction for hemodilution. Starting S-100B, IL-8 and PMN elastase values of the hydrocortisone group were within the ranges already known in patients with out-of-hospital cardiac arrest or severe traumatic brain injury. Stress doses of hydrocortisone resulted in a significant reduction in IL-8 serum, but not in S-100B serum and PMN elastase plasma concentrations in patients with hyperdynamic septic shock. For the first time, a similar extent of S-100B increase in serum of septic patients at the time of diagnosis was shown as reported for cardiac arrest or severe traumatic brain injury.

Effect of magnesium sulfate administration on blood-brain barrier in a rat model of intraperitoneal sepsis: a randomized controlled experimental study

Introduction

Permeability changes in the blood–brain barrier (BBB) and their possible contribution to brain edema formation have a crucial role in the pathophysiology of septic encephalopathy. Magnesium sulfate has been shown to have a protective effect on BBB integrity in multiple experimental models. In this study we determine whether magnesium sulfate administration could have any protective effects on BBB derangement in a rat model of sepsis.

Methods

This randomized controlled experimental study was performed on adult male Sprague–Dawley rats. Intraperitoneal sepsis was induced by using the infected fibrin–thrombin clot model. To examine the effect of magnesium in septic and sham-operated rats, a dose of 750 μmol/kg magnesium sulfate was given intramuscularly immediately after surgery. Control groups for both infected and sham-operated rats were injected with equal volume of saline. Those rats surviving for 24 hours were anesthetized and decapitated for the investigation of brain tissue specific gravity and BBB integrity by the spectrophotometric assay of Evans blue dye extravasations. Another set of experiments was performed for hemodynamic measurements and plasma magnesium level analysis. Rats were allocated into four parallel groups undergoing identical procedures.

Results

Sepsis significantly increased BBB permeability to Evans blue. The dye content of each hemisphere was significantly lower in the magnesium-treated septic rats (left hemisphere, 0.00218 ± 0.0005; right hemisphere, 0.00199 ± 0.0007 [all results are means ± standard deviation]) than in control septic animals (left hemisphere, 0.00466 ± 0.0002; right hemisphere, 0.00641 ± 0.0003). In septic animals treated with magnesium sulfate, specific gravity was higher (left hemisphere, 1.0438 ± 0.0007; right hemisphere, 1.0439 ± 0.0004) than in the untreated septic animals (left hemisphere, 1.0429 ± 0.0009; right hemisphere, 1.0424 ± 0.0012), indicating less edema formation with the administration of magnesium. A significant decrease in plasma magnesium levels was observed 24 hours after the induction of sepsis. The dose of magnesium that we used maintained the baseline plasma magnesium levels in magnesium-treated septic rats.

Conclusions

Magnesium administration attenuated the increased BBB permeability defect and caused a reduction in brain edema formation in our rat model of intraperitoneal sepsis.

Time-dependent mitochondrial-mediated programmed neuronal cell death prolongs survival in sepsis*

OBJECTIVE

To investigate whether apoptosis is a possible mechanism of brain dysfunction occurring in septic syndrome.

DESIGN

Experimental prospective study.

SETTING

Laboratory of Surgical Research at the University of Athens.

SUBJECTS

Male pathogen-free Wistar rats.

INTERVENTIONS

Rats (n = 112) were subjected to sepsis by cecal ligation and puncture. Sham-operated animals (n = 40) underwent the same procedure but without ligation or puncture. Septic animals were either randomly divided (n = 62) in six groups and studied at 6, 12, 24, 36, 48, and 60 hrs after the operation or monitored (n = 50) for 48 hrs as a survival study group. Sham-operated animals were killed at 6, 12, 24, 36, 48, and 60 hrs after the procedure. Brain and cecum were then removed and postfixed in paraffin sections. Apoptosis was evaluated by light microscopy in hematoxylin and eosin-stained specimens and by transmission electron microscopy. In paraffin-embedded sections, immunostaining for bax, bcl-2, cytochrome c, and caspase-8 was done.

MEASUREMENTS AND MAIN RESULTS

In septic rats, increased apoptosis was detected in neurons of the CA1 region of the hippocampus, in choroid plexus, and in Purkinje cells of the cerebellum. Bax immunopositivity was found decreased after the septic insult (p =.03). Bax immunoreactivity was altered as the septic syndrome evolved; it was up-regulated in the early stages (6-12 hrs) and progressively decreased in the late phases (p =.001). Cytochrome c presented a similar regional pattern of expression and was found to be the sole gene marker carrying an independent prognostic role (p =.03). Both bcl-2 and caspase-8 expression remained at constant levels at all times evaluated.

CONCLUSIONS

There is evidence that more neurons undergo apoptosis during sepsis than in normal brain tissue in certain sites where the blood-brain barrier is compromised. In this phenomenon, mitochondrial gene regulators such as bax and products such as cytochrome c seem to play important regulating and prognostic roles, respectively.

Pathogenesis of malaria and clinically similar conditions

There is now wide acceptance of the concept that the similarity between many acute infectious diseases, be they viral, bacterial, or parasitic in origin, is caused by the overproduction of inflammatory cytokines initiated when the organism interacts with the innate immune system. This is also true of certain noninfectious states, such as the tissue injury syndromes. This review discusses the historical origins of these ideas, which began with tumor necrosis factor (TNF) and spread from their origins in malaria research to other fields. As well the more established proinflammatory mediators, such as TNF, interleukin-1, and lymphotoxin, the roles of nitric oxide and carbon monoxide, which are chiefly inhibitory, are discussed. The established and potential roles of two more recently recognized contributors, overactivity of the enzyme poly(ADP-ribose) polymerase 1 (PARP-1) and the escape of high-mobility-group box 1 (HMGB1) protein from its normal location into the circulation, are also put in context. The pathogenesis of the disease caused by falciparum malaria is then considered in the light of what has been learned about the roles of these mediators in these other diseases, as well as in malaria itself.

Encéphalopathie cataméniale récurrente secondaire à un syndrome de choc toxique

INTRODUCTION

Neurological clinical manifestations are often observed in toxic shock syndromes. However they unusually dominate the clinical picture.

OBSERVATION

We present a case of recurrent catamenial encephalopathy, with epileptic seizures, revealing a menses toxic shock syndrome.

Differentiating the pathologies of cerebral malaria by postmortem parasite counts

To study the pathogenesis of fatal cerebral malaria, we conducted autopsies in 31 children with this clinical diagnosis. We found that 23% of the children had actually died from other causes. The remaining patients had parasites sequestered in cerebral capillaries, and 75% of those had additional intra- and perivascular pathology. Retinopathy was the only clinical sign distinguishing malarial from nonmalarial coma. These data have implications for treating malaria patients, designing clinical trials and assessing malaria-specific disease associations.

The neuropathology of septic shock

The neuropathological correlates of encephalopathy and autonomic dysfunction in septic shock are unclear. We performed post mortem analysis of 5 brain areas susceptible to ischemia and 5 autonomic nuclei (AN) in 23 patients who had died in our intensive care unit (ICU) from septic shock and 8 dying from non-septic shock as well as 5 controls who had died suddenly from extracranial injury. Proinflammatory cytokine (IL1-beta and TNF-alpha) and inducible nitric oxide synthase (iNOS) expression was assessed by immunocytochemistry. Abnormalities in septic shock were: hemorrhages (26%), hypercoagulability syndrome (9%), micro-abscesses (9%), multifocal necrotizing leukoencephalopathy (9%) and ischemia (100%). The incidence of cerebral hemorrhage or hypercoagulability syndrome was not related to clotting disturbances. The intensity of ischemia within susceptible areas was the same in both ICU groups, but more pronounced in the autonomic centers of septic patients (P < 0.0001). Neuronal apoptosis assessed using anti-caspase 3 immunocytochemistry and in situ end labeling was more pronounced in the autonomic nuclei of septic patients. (P < 0.0001). TNF-alpha expression did not differ between groups but vascular iNOS expression assessed by immunocytochemistry was higher in sepsis (P<0.0001) and correlated with autonomic center neuronal apoptosis (P < 0.02). We conclude that septic shock is associated with diffuse cerebral damage and specific autonomic neuronal apoptosis which may be due to circulating factors particularly iNOS.

Apoptosis of neurons in cardiovascular autonomic centres triggered by inducible nitric oxide synthase after death from septic shock

BACKGROUND

Results of experimental and clinical studies have shown that septic shock is associated with cardiovascular autonomic failure. Thus, we aimed to investigate the existence of ischaemia and apoptosis within the cerebral autonomic centres that control the cardiovascular system in patients with septic shock.

METHODS

In a prospective cohort study, we did post-mortem examinations of supraoptic and paraventricular nuclei, cerebral amygdala, locus coeruleus, and medullary autonomic nuclei in 19 patients with septic shock, seven with non-septic shock and five who died suddenly from extracranial injury. Ischaemic and apoptotic neurons and microglial cells, and expression of tumour necrosis factor alpha (TNFalpha) and inducible nitric oxide synthase (iNOS) were scored.

FINDINGS

Ischaemic, neuronal, and microglial apoptosis scores differed between groups (p=0.0007, p<0.0001, and p=0.0037, respectively) and were higher in patients with septic shock than in those with non-septic shock (p=0.0033, p=0.0005, and p=0.0235, respectively), and extra-cranial injury related deaths (p=0.0027, p=0.0007, and p=0.0045, respectively). There was little microglial activation and glial expression of TNFalpha. The scores for endothelial iNOS expression were different between the three groups (p<0.0001), and were higher in septic shock than in non-septic shock (p=0.0009) and than in extracranial injury related deaths (p=0.0007). Vascular expression of iNOS also correlated (Spearman tau=0.57) with autonomic-centre neuronal apoptosis in the combined septic and non-septic shock group.

INTERPRETATION

Septic shock is associated with neuronal and glial apoptosis within the autonomic centres, which is strongly associated with endothelial iNOS expression.

Enhanced expression of E-selectin on the vascular endothelium of peripheral nerve in critically ill patients with neuromuscular disorders

Neuropathic complication often occurs in critically ill patients, and changes in the microcirculation of the peripheral nerve have been suggested to play a role in the pathogenesis of the nerve lesion. We report the results of a pathological and immunohistochemical study of superficial peroneal nerve biopsy specimens in a series of 22 critically ill patients with sepsis and neuromuscular disorders. Eight patients had histopathological features of axonal neuropathy compatible with critical illness polyneuropathy (CIP). The nerve lesions ranged in severity from mildly reduced myelin-fiber density with sporadic axonal degeneration to marked fiber loss with abundant degenerative changes. In no patient did we detect evidence of primary demyelinization or inflammatory infiltrates. We analyzed the immunohistochemical expression of E-selectin, vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor alpha (TNF-alpha) in nerve microvessels. Expression of E-selectin was significantly increased in endothelium of epineurial and endoneurial vessels, suggesting endothelial cell activation. These findings again confirm axonal degeneration as the major pathological feature of CIP. Our immunohistochemical data provide first evidence that activation of the endothelial cells of the microvessels in the endoneurium of human peripheral nerve does occur during sepsis. This specific activation might have implications with the mechanisms responsible for the axonopathy in critically ill patients.

Progress in clinical neurosciences: sepsis-associated encephalopathy: evolving concepts

Systemic sepsis commonly produces brain dysfunction, sepsis-associated encephalopathy, which can vary from a transient, reversible encephalopathy to irreversible brain damage. The encephalopathy in the acute phase clinically resembles many metabolic encephalopathies: a diffuse disturbance in cerebral function with sparing of the brain stem. The severity of the encephalopathy, as reflected in progressive EEG abnormalities, often precedes then parallels dysfunction in other organs. Recent research has revealed a number of potentially important, non-mutually exclusive, mechanisms that have therapeutic implications.

Somatosensory evoked potentials as predictor of systemic inflammatory response syndrome in pigs?

OBJECTIVE

Sepsis or systemic inflammatory response syndrome (SIRS) is often associated with encephalopathy (70%), which has been described as an early symptom resulting in several diseases. The present study investigated somatosensory evoked potentials (SEP) as an indicator or even a predictor of cerebral dysfunction evaluated in an experimental model of SIRS in pigs.

METHODS

Eight Göttinger minipigs were included in the study. SIRS was mediated by induction of pancreatitis due to injection (ductus pancreaticus) of 500 mg/kg sodium taurocholate and 2.5 IU/kg enterokinase. Monitored parameters were: arterial blood-central venous-pulmonary arterial pressure, and cardiac output, systemic vascular resistance, and body temperature. SEP were recorded from centroparietal vs. frontal areas after electrical stimulation of the right forepaw.

RESULTS

At least 33% loss of vascular resistance from baseline (SIRS criteria) occurred in all animals within 4-18 h. Baseline recordings in all anesthetized animals indicated primary cortical responses to electrical stimuli identified by peak latencies between 15-20 ms (SEP(P15-20)). Attenuations in the amplitudes with significant median decreases of 46% were observed at least 4 h before the defined hemodynamic SIRS criteria.

CONCLUSIONS

The present data show a trend for the attenuation in SEP amplitudes as an indicator of systemic inflammatory response. SEP monitoring may be a sensitive marker of developing early changes in cerebral function due to SIRS-related encephalopathy.

Protective effect of glial cells against lipopolysaccharide-mediated blood-brain barrier injury

Numerous infections of the central nervous system are characterized by altered blood-brain barrier (BBB) functions leading to brain damage. To study the mechanisms that cause BBB disruption in these pathologies, we used an in vitro BBB model consisting of a coculture of brain capillary endothelial cells and glial cells. When these endothelial cells were submitted alone to lipopolysaccharide (LPS), added in the luminal compartment, a huge increase in the paracellular permeability of the monolayer was observed. As glial cells surrounding the brain capillaries are of prime importance in specifying at least some cellular properties, we investigated whether glial cells would be able to modulate this endothelial cell response to LPS. When endothelial cells were incubated with LPS added luminally, in the presence of glial cells, LPS surprisingly had no effect on the endothelial cell monolayer permeability, suggesting a protective effect of glial cells on the LPS-mediated injury. As in our experiments, the endotoxin does not interact with the glial cell population. This protective effect suggests a close communication between cerebral endothelial cells and brain parenchymal cells. In our coculture model, the glial cell population is a mixture of astrocytes, oligodendrocytes, and microglial cells. Further experiments performed with purified astrocytes showed that microglial cells or oligodendrocytes, or both, are essential for the complete protection of the endothelial cell monolayer integrity. All these results are direct evidence for a modulatory effect of glial cells on brain capillary endothelial cell response in the pathogenesis of endotoxemia.

Clinical chorioamnionitis, elevated cytokines, and brain injury in term infants

OBJECTIVES

To determine the initial inflammatory cytokine response in term infants born to mothers with clinical chorioamnionitis and to assess whether the cytokine response is associated with birth depression, abnormal neurologic examination, and hypoxic-ischemic encephalopathy (HIE).

METHODS

Infants who were exposed to chorioamnionitis and admitted to the neonatal intensive care unit (n = 61) were studied prospectively. Cytokine concentrations were measured from umbilical cord blood and at 6 and 30 hours after birth. Control values (n = 50) were determined from cord blood of healthy term infants. Enzyme-linked immunosorbent assays were performed for interleukin (IL)-1beta; IL-6; IL-8; regulated on activation, normal T-cell expressed and secreted (RANTES); macrophage inflammatory protein-1alpha; and tumor necrosis factor-alpha. Serial blinded neurologic examinations using a modified Dubowitz score were performed simultaneously at 6 and 30 hours.

RESULTS

Cord IL-6 (1071 +/- 1517 vs 65 +/- 46 pg/mL), IL-8 (2580 +/- 9834 vs 66 +/- 57 pg/mL), and RANTES (95 917 +/- 16 518 vs 54 000 +/- 14 306 pg/mL) concentrations only were higher in infants with chorioamnionitis versus control infants. IL-6 increased at 6 hours to 1451 +/- 214 pg/mL, followed by a 5-fold decline at 30 hours in contrast to progressive decreases over time in IL-8 and RANTES. There was no relationship between cytokines and birth depression. Modified Dubowitz score correlated with IL-6 at 6 hours (r = 0.5). Infants with HIE/seizures (n = 5) had significantly higher cytokine concentrations at 6 hours versus infants without either (n = 56): IL-6 (3130 vs 1219 pg/mL), IL-8 (5433 vs 780 pg/mL), and RANTES (97 396 vs 46 914 pg/mL).

CONCLUSIONS

There was a significant association between abnormalities in the neurologic examination and cytokine concentrations, with the highest cytokines concentrations observed in infants who developed HIE/seizures.

Neuromuscular disorders in the intensive care unit

Neuromuscular disorders encountered in the ICU can be categorized as muscular diseases that lead to ICU admission and those that are acquired in the ICU. This article discusses three neuromuscular disorders can lead to ICU admission and have a putative immune-mediated pathogenesis: the Guillian-Barré syndrome, myasthenia gravis, and dermatomyositis/polymyositis. It also reviews critical care polyneuropathy and ICU acquired myopathy, two disorders that, alone or in combination, are responsible for nearly all cases of severe ICU acquired muscle weakness.

Cerebral blood flow and oxidative metabolism during human endotoxemia

The proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), has been suggested to mediate septic encephalopathy through an effect on cerebral blood flow (CBF) and metabolism. The effect of an intravenous bolus of endotoxin on global CBF, metabolism, and net flux of cytokines and catecholamines was investigated in eight healthy young volunteers. Cerebral blood flow was measured by the Kety-Schmidt technique at baseline (during normocapnia and voluntary hyperventilation for calculation of subject-specific cerebrovascular CO reactivity), and 90 minutes after an intravenous bolus of a reference endotoxin. Arterial TNF-alpha peaked at 90 minutes, coinciding with a peak in subjective symptoms. At this time, CBF and Paco were significantly reduced compared to baseline; the CBF decrease was readily explained by hypocapnia. The cerebral metabolic rate of oxygen remained unchanged, and the net cerebral flux of TNF-alpha, interleukin (IL)-1beta, and IL-6 did not differ significantly from zero. Thus, high circulating levels of TNF-alpha during human endotoxemia do not induce a direct reduction in cerebral oxidative metabolism.

Infection markers and early signs of neonatal encephalopathy in the term infant

Recent evidence points to an association between intrauterine infection and cerebral palsy (CP) in the preterm as well as the term infant. The mechanisms that link these two conditions are unclear. Chorioamnionitis is a common clinical problem complicating 5-10% of pregnancies, whereas the incidence of CP attributed to intrapartum asphyxia is rare. Chorioamnionitis may result in brain injury as a result of interruption of placental blood flow (asphyxia), or via fever and/ or the cytokine release associated with infection. This review will attempt to establish the link between perinatal infection and brain damage in term infants. The characteristics of the perinatal inflammatory response, the potential mechanisms of brain injury associated with infection, and the clinical characteristics of neonatal encephalopathy will be discussed.

[Febrile states and the encephalopathy syndrome]

<zakljucak> Sepsa, odnosno septicka encefalopatija predstavlja uobicajeni termin koji ukazuje na razvoj znakova mozdane disfunkcije u toku i u vezi sa prisustvom mikroorganizama i njihovih toksina u krvi. Septicka encefalopatija po pravilu nije izolovana, vec je pracena razvojem ostecenja mnogih organskih sistema. Razlikovanje septicke encefalopatije i encefalopatskih sindroma kao posljedice drugih oboljenja - poremecaja, a koja su pracena febrilnim stanjem predstavlja imperativ radi planiranja i sprovodjenja adekvatnog i pravovremenog dijagnostickog, terapijskog i preventivnog programa, sto daje najvece izglede oboljelim.

Neurologic complications of transplantation

BACKGROUND

Organ transplantation is one of the most dynamic fields in medicine and has evolved into a life-saving option for thousands of patients with previously fatal conditions. The posttransplantation clinical course is frequently associated with neurologic complications that are usually related to pretransplant morbidity, the surgical procedure of transplantation, immunosuppression, and opportunistic infection.

REVIEW SUMMARY

Neurologic complications of organ transplantation may be divided into complications common to all types of allografts and complications that are specific for a particular type of organ transplantation. The most common complications include seizures, opportunistic central nervous system (CNS) infection, metabolic encephalopathy, stroke, intracranial hemorrhage, and drug-related adverse events. Opportunistic CNS infection may have a subtle presentation and should not be overlooked, as the consequences of delayed treatment may be grave. Neurotoxicity of immunosuppressive agents is also a frequent cause of neurologic complications and may occur in the setting of normal serum drug levels. The clinical course of transplant patients is frequently complex, requiring close cooperation between the transplant team and specialty consultants. Prolonged survival of transplant patients will shift the focus of neurologic complications from acute, perioperative to chronic complications of immunosuppression.

CONCLUSIONS

Neurologic complications of organ transplantation are commonly related to opportunistic infection or neurotoxicity of immunosuppressive agents, requiring careful titration of immunosuppression. Timely diagnosis of CNS infection or other causes of neurologic dysfunction may significantly improve recovery and outcome in these patients.

From farm to table to brain: foodborne pathogen infection and the potential role of the neuro-immune-endocrine system in neurotoxic sequelae

The American diet is among the safest in the world; however, diseases transmitted by foodborne pathogens (FBPs) still pose a public health hazard. FBPs are the second most frequent cause of all infectious illnesses in the United States. Numerous anecdotal and clinical reports have demonstrated that central nervous system inflammation, infection, and adverse neurological effects occur as complications of foodborne gastroenteritis. Only a few well-controlled clinical or experimental studies, however, have investigated the neuropathogenesis. The full nature and extent of neurological involvement in foodborne illness is therefore unclear. To our knowledge, this review and commentary is the first effort to comprehensively discuss the issue of FBP induced neurotoxicity. We suggest that much of this information supports the role of a theoretical model, the neuro-immune-endocrine system, in organizing and helping to explain the complex pathogenesis of FBP neurotoxicity.

Critical illness neuromuscular disease: clinical, electrophysiological, and prognostic aspects

BACKGROUND

Critical illness neuromuscular disease, which has been recognised as a distinct clinical entity in adults, remains poorly described in children.

AIMS

To assess retrospectively the clinical, electrophysiological, and prognostic features of the disease.

METHODS

Retrospective study in a children's university hospital.

RESULTS

Five critically ill patients presented with generalised paralysis, associated with long lasting failure to breathe in three. The cause of the generalised paralysis was critical illness neuropathy in two, acute myopathy in two, and mixed neuromyopathy in one.

CONCLUSIONS

Neuromuscular disease should be suspected in critically ill children with muscle weakness. Because corticosteroids and muscle relaxants appear to trigger some types of intensive care unit neuromuscular disease in children, their use should be restricted or administered at the lowest doses possible.

Critical illness polyneuropathy

Critical illness polyneuropathy is a self-limited acute axonal neuropathy that develops during treatment of severely ill patients and remits spontaneously once the critical condition is under control. Clinical manifestations include muscle weakness and atrophy, delayed weaning from the respirator, and prolongation of the mobilization phase. The pathogenesis is not understood in detail but most authors assume that the inflammatory cascade that mediates the systemic inflammatory response and multiple organ failure play a pivotal role. This review summarizes current knowledge of this common neuropathic complication during intensive care treatment.

Electrophysiologic studies in critical illness associated weakness: myopathy or neuropathy--a reappraisal

OBJECTIVE

Unexplained weakness in critically ill patients is recognized with increasing frequency. However, it is debated whether the condition is a peripheral neuropathy or a myopathy. Diagnostic difficulties can arise from multiple sources that are not generally a factor in other neuromuscular conditions. Conventional electrodiagnostic techniques may provide only non-specific data, clinical examination is often hampered, and muscle biopsy is not a practical screening tool.

METHOD

To improve diagnostic yield, we studied 22 consecutive patients with critical illness associated weakness with additional electrodiagnostic techniques, including direct muscle stimulation, quantitative electromyography, and motor unit number estimation.

RESULTS

The applied techniques supported an underlying myopathy in all the patients examined. The diagnosis was confirmed by muscle biopsy in 9 patients. Additional lesser features of neuropathy were concomitantly present in one patient who also underwent sural nerve biopsy.

CONCLUSIONS

The study suggests that myopathy is much more common than polyneuropathy in critical illness. Suspicion of this entity should be high in this setting even without exposure to corticosteroids or non-depolarizing blocking agents.

Rehabilitation following bone marrow transplantation

Bone marrow transplantation and stem cell transplantation are increasingly used to treat hematologic malignancies and some solid tumors. The treatment entails bone marrow-ablative therapies and intensive medical support to sustain the patient through pancytopenia and other complications of the disease, transplantation process, or drug side effects. Patients who develop graft-versus-host disease are the most difficult subset of transplant recipients to manage. Most transplant recipients perform at normal or near-normal functional levels at the inception of the transplantation process but are at high risk for developing functional deficits as a result of cumulative impairments. These impairments arise from their disease, their prior cancer treatment, transplant induction, graft-versus-host disease, immobility, infection, steroid-related side effects, and other sequelae of transplantation. Preventive and preemptive rehabilitation interventions can minimize functional loss and facilitate recovery, but the transplantation team must be sensitive to and regularly assess for early functional declines in these patients. The physiatrist and the other members of the rehabilitation team must be thoroughly acquainted with the unique needs and challenges of the bone marrow transplantation population in order to design and modify treatment programs effectively and safely. Outcome research has shown that some patients have continued limitations in function despite successful transplantation. Few evidence-based data are available that addresses factors correlating with poor functional outcomes other than graft-versus-host disease. However, this disease has not been investigated utilizing objective functional instruments. Future research should more clearly elucidate the functional impact of allogeneic and autologous transplants by using standardized physical performance measures as well as thorough function-based symptomatology questionnaires.

Abnormal sleep/wake cycles and the effect of environmental noise on sleep disruption in the intensive care unit

Little is known about sleep/wake abnormalities in intensive care and less is known about the mechanisms responsible for these abnormalities. We studied 22 (20 mechanically ventilated) medical intensive care unit (ICU) patients with continuous polysomnography (PSG) and environmental noise measurements for 24-48 h to characterize sleep-wake patterns and objectively determine the effect of environmental noise on sleep disruption. All 22 patients demonstrated sleep-wake cycle abnormalities. There were large variations in total sleep time (TST) with the mean total sleep time per 24-h study period of 8.8 +/- 5.0 h. Sleep-wake cycles were fragmented and nonconsolidated with a mean of 57 +/- 18% and 43 +/- 18% of the TST occurring during the day and night, respectively. Environmental noise was responsible for 11.5 and 17% of the overall arousals and awakenings from sleep, respectively. The mean noise arousal index was 1.9 +/- 2.1 arousals/h sleep.

CONCLUSIONS

(1) ICU patients are qualitatively, but not necessarily quantitatively, sleep deprived; and (2) although environmental noise is in part responsible for sleep-wake abnormalities, it is not responsible for the majority of the sleep fragmentation and may therefore not be as disruptive to sleep as the previous literature suggests.

Pathophysiology of septic encephalopathy: a review

OBJECTIVES

Encephalopathy is a common complication of sepsis. This review describes the different pathologic mechanisms that may be involved in its etiology.

DATA SOURCES

The studies described here were derived from the database PubMed (http:¿¿www.nlm.nih.gov) and from references identified in the bibliographies of pertinent articles and books. The citations are largely confined to English language articles between 1966 and 1998. Older publications were used if they were of historical significance.

STUDY SELECTION

All investigations in which any aspect of septic encephalopathy was reported were included. This selection encompasses clinical, animal, and in vitro cell culture work.

DATA EXTRACTION

The literature cited was published in peer-reviewed clinical or basic science journals or in books.

DATA SYNTHESIS

Contradictions between the results of published studies are discussed.

CONCLUSIONS

The most immediate and serious complication of septic encephalopathy is impaired consciousness, for which the patient may require ventilation. The etiology of septic encephalopathy involves reduced cerebral blood flow and oxygen extraction by the brain, cerebral edema, and disruption of the blood-brain barrier that may arise from the action of inflammatory mediators on the cerebrovascular endothelium, abnormal neurotransmitter composition of the reticular activating system, impaired astrocyte function, and neuronal degeneration. Currently, there is no treatment.

Critical illness polyneuropathy and myopathy (CIPNM): evidence for local immune activation by cytokine-expression in the muscle tissue

In a longitudinal prospective study a muscle biopsy was taken from 30/32 (33%) of the 98 patients who developed critical illness polyneuropathy and myopathy (CIPNM). Neuropathic changes were found in 37%, myopathic in 40%, and a combination in 23% of the biopsies. The immunohistopathology showed macrophages and Th-cells in 40% and 60% of the muscle biopsies respectively. Small mainly perivascular infiltrates contained macrophages and Th-cells. ICAM-1, VCAM and MAC were found on the vascular endothelium in 58%, 53% and 79% respectively. In all biopsies there was an upregulation of both HLA-I and HLA-DR. Proinflammatory cytokines and TNFalphaR75 were also produced locally (IL-1beta in 71%, IFN-gamma in 40%, IL-12 in 73%, TNFalphaR75 in 90%). The anti-inflammatory cytokine IL-10 was simultaneously expressed in 96% of the biopsies. HLA-DR, TNFalphaR75 and IL-10 differed significantly when compared with control muscle biopsies. Our data provide evidence that small numbers of activated leukocytes producing both pro- and anti-inflammatory cytokines infiltrate skeletal muscle of CIPNM patients. We propose that the local balance of leukocyte activities is of importance in the pathophysiology of muscle weakness in CIPNM.

Acute weakness syndromes in the critically ill patient

Over the past three decades there has been increasing interest in acute weakness syndromes in critically ill mechanically ventilated patients. Many of these patients require rehabilitation, and some understanding of potential etiologies and functional outcomes for these syndromes is useful to rehabilitation practitioners. A clearer understanding of these syndromes has evolved over time, as has the terminology to describe these conditions. This article will review commonly encountered causes of acute weakness in critically ill patients, including disorders of the peripheral nerves, the neuromuscular junction, and muscle.

[Critical illness polyneuropathy: case report]

The critical illness polyneuropathy has an acute onset and an axonal predominantly motor nature. It occurs in sepsis or in multiple organ failure usually requiring mechanical ventilation in critical care units. Electroneuromyography corroborates the diagnosis. Usually it courses satisfactorily. We report on a 35-year-old female patient who, after a permanence in a critical care unit due to sepsis and removal of a dead phetus, developed tetraparesis. She had an important improvement in four months. Electromyography showed reduction of amplitude of motor and sensory action potentials, positive waves and fibrillations. The sural nerve biopsy showed axonmyelinic neuropathy. These findings are consistent with those in literature and we believe they support the diagnosis of critical illness neuropathy.

Neurologic complications in the intensive care unit

Neurologic complications resulting from critical illness and intensive care unit therapies are common, but frequently unrecognized because these patients are often intubated, sedated, and, occasionally, receiving neuromuscular blocking agents. Neurologic complications are associated with an increased intensive care unit mortality. This article discusses central nervous system complications that are secondary to critical illness or to therapeutic interventions in the critically ill patient.

[The use of curare-like agents in resuscitation]

OBJECTIVE

To analyse current data on use of neuromuscular blocking agents (NBA) in the intensive therapy unit (ITU) patients and to propose practice guidelines.

DATA SOURCES

We did a Medline search of French and English language articles on NBA administration in ITU patients from 1960 to 1998. Data were also selected from our own collection of articles and books.

STUDY SELECTION

Original articles, clinical cases, letters to the editor and review articles were considered.

DATA EXTRACTION

Data on pharmacology of NBA in the ITU patient were extracted, as well as data on administration patterns and cost.

DATA SYNTHESIS

The indications for myorelaxation in ITU patients include either short term use, as in anaesthesia, or long term administration for facilitation of mechanical ventilation, control of increased intracranial pressure, status epilepticus, tetanus and oxygen demand in case of muscular hyperactivity, diagnostic and therapeutic procedures facilitation. A beneficial effect of NBA on the prognosis of the disease for which these agents have been used is not yet proven. Suxamethonium, because for its short onset time and duration of action, is the agent of choice for endotracheal intubation if myorelaxation is required. Among the benzylisoquinolines, atracurium and besilate of cisatracurium are convenient agents in ITU patients, whereas mivacurium is of no special interest. Among the aminosteroids, pancuronium and vecuronium are the most often used agents in the ITU. Rocuronium has not yet been extensively assessed. Myorelaxants carry risks for morbidity and mortality. The difficulty to assess the neurological status and the level of sedation is a recognised adverse effect. An accidental disconnection from the circuit and the resulting asphyxia is nowadays recognised without delay by the ventilator. NBAs increase the rate of bronchopulmonary infections. Cardiovascular complications include extreme bradycardia or sinus arrest following vecuronium administration, and cardiac arrest after suxamethonium injection mainly in burned or traumatised patients. Conversely to anaesthesia, NBAs do not carry a significant risk for anaphylactic or anaphylactoid complications in the ITU. Tachyphylaxis occurs mainly in burns and other pathologies modifying acetylcholine receptors. Neuromuscular complications include myopathy from steroids, postparalytic syndrome, deconditioning syndrome and intensive care polyneuropathy. Prolonged curarisation after discontinuation of NBA administration has a multifactorial origin and must be differentiated from neuromuscular complications. For prolonged neuromuscular blockade, pancuronium, vecuronium and atracurium are the agents of choice. The association with an adequate sedation is essential. Assessment of depth of neuromuscular blockade is not based on clinical symptoms but on train-of-four (TOF) twitch monitoring. A convenient basic relaxation is usually obtained with the suppression of the two last responses to TOF.

CONCLUSION

The use of NBA in ITU patient should result from a rational decision making procedure, the blockade titrated with a TOF monitor and maintained as superficially and shortly as possible.

Muscle fibre atrophy in critically ill patients is associated with the loss of myosin filaments and the presence of lysosomal enzymes and ubiquitin

Muscle wasting and weakness are common features of patients with critical illnesses, and may impair their recovery. This study examines whether cytoskeletal and contractile proteins are damaged, and which proteolytic mechanisms might be involved, in the muscle fibre atrophy or necrosis associated with the acute myopathy of critically ill patients. Ninety-eight muscle biopsies were obtained by the conchotome method from 57 critically ill patients and examined morphometrically and by immunohistochemical labelling. Sequential biopsies showed a mean reduction in fibre cross-sectional areas of 3-4% per day. More intense immunolabelling for desmin was seen in the smaller fibres of 52% of the biopsies, while immunolabelling for dystrophin, actin and myosin heavy chains was maintained. Myosin ATPase activity was weak in the smaller fibres in some biopsies, and electron microscopy showed the loss of myosin filaments in atrophic fibres. These changes suggest that loss of the filamentous structure of myosin, without degradation of the immunolabelled epitopes, leads to the collapse of the intermyofibrillar desmin network. Fibres with abnormal desmin labelling showed increased cathepsin B, lysozyme and ubiquitin immunolabelling. Nine cases showed increased immunolabelling for heat shock protein 72. The changes in desmin immunolabelling were more prevalent in patients with higher APACHE II scores on admission, but were not related to other clinical features. The results indicate that fibre atrophy is associated with myosin filament depolymerization and the presence of several proteolytic enzymes. In our study, these changes occurred in patients who were critically ill but who did not receive large doses of steroids or neuromuscular blocking agents.

Cerebral blood flow is proportional to cardiac index in patients with septic shock

PURPOSE

In patients with septic shock, the cardiac index is often increased. Maldistribution of blood flow and regional hypoperfusion has been implicated as a key factor in the pathogenesis of organ dysfunction in these patients. We have investigated the relationship between cerebral blood flow and cardiac index in patients with septic shock.

MATERIALS AND METHODS

We used Doppler ultrasound techniques to investigate limb and carotid blood flow in 15 patients with septic shock and 9 nonseptic controls.

RESULTS

In the nonseptic control patients, common femoral and brachial blood flow were proportional to cardiac index (r=0.73 and 0.76; P=.038 and .017, respectively) reflecting a protective redistribution of flow to more vital organs. However, this relationship was absent in patients with septic shock (r=0.23 and 0.21). Furthermore, in the septic patients but not the nonseptic controls, cerebral blood flow was correlated with the cardiac index (r=0.66, P < .05 vs r=-0.36, NS in nonseptic controls). Carotid flow was independent of mean arterial pressure, PaCO2 and PaO2 in patients with septic shock.

CONCLUSIONS

These data are consistent with a loss of autoregulation of cerebral blood flow and a change in the control of limb blood flow in humans with septic shock.

Stroke in the medical intensive-care unit

OBJECTIVE

To analyze the occurrence and outcome of new-onset stroke in critically ill patients admitted to a medical intensive-care unit.

MATERIAL AND METHODS

We reviewed the medical records of patients admitted to the medical intensive-care units of two hospitals between 1985 and 1995. In addition, computed tomographic scans or scan reports were assessed.

RESULTS

We identified 19 patients with a critical medical illness and a new-onset stroke. Of this study group, ischemic stroke developed in 10 patients, 8 of whom were found to have bihemispheric infarction. A single territory infarct (the middle cerebral artery territory) was noted in two patients. The presumed mechanisms for ischemic stroke were disseminated intravascular coagulation (N = 6), cholesterol embolization (N = 1), discontinuation of warfarin therapy before an invasive procedure (N = 1), septic emboli (N = 1), and cardioversion (N = 1). In nine patients, an intracranial hemorrhage developed. Seven patients had a single lobar hematoma, whereas multiple intracerebral hematomas were found in two patients. Disseminated intravascular coagulation and rupture of a mycotic aneurysm in proven infective endocarditis were the most common mechanisms for hemorrhagic stroke. In all patients with an ischemic stroke, sudden hemiparesis rapidly progressed to coma. In patients with an intracranial hematoma and sudden onset of coma, unilateral fixed pupil was the most common initial manifestation. Of the 19 patients, 17 died and 2 remained severely disabled.

CONCLUSION

Coma is a common initial manifestation of stroke in patients with a critical medical illness, and disseminated intravascular coagulation has a major etiologic role. New-onset stroke in the setting of critical medical illness generally is a complication in a terminally ill patient.

Causes of neuromuscular weakness in the intensive care unit: a study of ninety-two patients

The spectrum of neuromuscular disorders among intensive care unit (ICU) patients has shifted toward disorders acquired within the ICU and away from "traditional" neuromuscular disorders that lead to ICU admission. We sought to assess this spectrum by determining the causes and relative frequencies of neuromuscular disorders that led to electromyography (EMG) examinations in our ICU population. Ninety-two patients were studied over a 4 1/2-year period. Twenty-six (28%) had neuromuscular disorders (mainly Guillain-Barré syndrome, myopathy, and motor neuron disease) that led to ICU admission. Among patients who developed weakness in the ICU, there was a predominance of organ transplant patients and patients with the systemic inflammatory response syndrome and multiorgan dysfunction. Thirty-nine (42%) developed acute myopathy (consistent with critical illness myopathy in most), and 13% developed acute axonal sensorimotor polyneuropathy (mainly critical illness polyneuropathy). Patients with acute myopathy and acute axonal sensorimotor polyneuropathy had similar functional outcomes. We conclude that among patients who underwent EMG in our ICU population, acute myopathy is three times as common as acute axonal polyneuropathy, and the outcomes from acute myopathy and acute axonal polyneuropathy may be similar.