Neurological manifestation of carbon monoxide poisoning

Treatment with normobaric or hyperbaric oxygen and its effect on neuropsychometric dysfunction after carbon monoxide poisoning: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Carbon monoxide (CO) poisoning may result in acute neurological sequelae, cognitive sequelae, and delay neurological sequelae. The administration of hyperbaric oxygen (HBO) to prevent the development of delayed neurological sequelae in CO poisoning have extensively investigated but conflicting results have been reported. We performed a systematic literature review and meta-analysis of randomized controlled trials (RCTs) evaluating HBO treatment and its effect on neuropsychometric dysfunction after CO poisoning.

METHODS

We searched Medline, Embase, Pubmed, and the Cochrane Register of Controlled Trials from inception to December 2017. Eligible studies compared HBO therapy with normobaric oxygen (NBO) in patients with CO poisoning.

RESULTS

Six studies compared HBO with NBO in CO poisoning patients. Compared with patients treated with NBO, a lower percentage of patients treated with HBO reported headache (16.2% vs 16.5%, relative risk [RR] = 0.83, 95% CI = 0.38-1.80), memory impairment (18.2% vs 23.8%, RR = 0.80, 95% CI = 0.43-1.49), difficulty concentrating (15.0% vs 18.4%, RR = 0.86, 95% CI = 0.55-1.34), and disturbed sleep (14.7% vs 16.2%, RR = 0.91, 95% CI = 0.59-1.39). Two sessions of HBO treatment exhibited no advantage over one session.

CONCLUSIONS

The meta-analysis indicated that compared with CO poisoning patients treated with NBO, HBO treated patients have a lower incidence of neuropsychological sequelae, including headache, memory impairment, difficulty concentrating, disturbed sleep, and delayed neurological sequelae. Taking into consideration the cost-effectiveness of one session of HBO, one session of HBO treatment could be an economical option for patients with CO poisoning with high severity.

The usefulness of diffusion-weighted magnetic resonance imaging performed in the acute phase as an early predictor of delayed neuropsychiatric sequelae in acute carbon monoxide poisoning

Delayed onset of neuropsychiatric symptoms after apparent recovery from acute carbon monoxide (CO) poisoning has been described as delayed neuropsychiatric sequelae (DNS). No previous study has determined whether early use of diffusion-weighted magnetic resonance imaging (DWI) can predict which patients will develop DNS in the acute CO poisoning. This retrospective observational study was performed on adult patients with acute CO poisoning consecutively treated over a 17-month period. All included patients with acute CO poisoning underwent DWI to evaluate brain injury within 72 h after CO exposure. DWI was evaluated as follows: (1) presence of pathology, (2) number of pathologies, (3) asymmetry, and (4) location of pathology. Patients were divided into two groups. The DNS group was composed of patients with delayed sequelae, while the non-DNS group included patients with no sequelae. A total of 102 patients with acute CO poisoning were finally enrolled in this study. DNS developed in 10 patients (9.8%). Between the DNS group and the non-DNS group, presence of pathology on DWI and initial Glasgow Coma Scale (GCS) showed significant difference. There was also a statistical difference between the non-DNS group and DNS group in terms of CO exposure time, troponin I, rhabdomyolysis, acute kidney injury, and pneumonia. The presence of pathology in DWI and initial GCS (cutoff: <12) at the emergency department served as an early predictors of DNS.

Initial diffusion-weighted MRI and long-term neurologic outcomes in charcoal-burning carbon monoxide poisoning

CONTEXT

This study assessed the results of diffusion-weighted imaging (DWI) at presentation for acute charcoal-burning carbon monoxide (CO) poisoning and investigated whether the initial DWI results can predict long-term neurologic outcomes.

METHODS

The study included 128 patients who suffered from CO poisoning after burning charcoal and underwent DWI. These patients were divided into two groups based on imaging results: a normal DWI group and an abnormal DWI group. Data regarding clinical courses and long-term neurologic outcomes (persistent severe neurologic sequelae) were collected and compared.

RESULTS

The rate of abnormal DWI findings at presentation was 23.4%, and the most common site of abnormalities was the globus pallidus. All lesions in abnormal DWI had decreased apparent diffusion coefficient (ADC) values. The long-term neurologic state was assessed at a median follow-up of 19.5 months, and the frequency of poor long-term neurologic outcome was significantly higher in the abnormal DWI group (40.0% in the abnormal DWI group vs. 1.0% in the normal DWI group; p < .001). Abnormal DWI (odds ratio [OR]): 31.3, 95% confidence interval [CI]: 2.5-397) and old age (OR 1.1, 95% CI: 1.001-1.13) were independent factors for poor long-term neurologic outcomes, whereas the Glasgow Coma Scale score at presentation (OR: 0.7, 95% CI: 0.6-0.9) was negatively associated with the risk of poor long-term neurologic outcome.

CONCLUSIONS

In cases involving CO poisoning due to charcoal burning, DWI at presentation may help predict the long-term neurological outcome after discharge.

Serum neuron-specific enolase as an early predictor of delayed neuropsychiatric sequelae in patients with acute carbon monoxide poisoning

Delayed onset of neuropsychiatric symptoms after apparent recovery from acute carbon monoxide (CO) poisoning has been described as delayed neuropsychiatric sequelae (DNS). To date, there have been no studies on the utility of serum neuron-specific enolase (NSE), a marker of neuronal cell damage, as a predictive marker of DNS in acute CO poisoning. This retrospective observational study was performed on adult patients with acute CO poisoning consecutively treated over a 9-month period. Serum NSE was measured after emergency department arrival, and patients were divided into two groups. The DNS group comprised patients with delayed sequelae, while the non-DNS group included patients with none of these sequelae. A total of 98 patients with acute CO poisoning were enrolled in this study. DNS developed in eight patients. The median NSE value was significantly higher in the DNS group than in the non-DNS group. There was a statistical difference between the non-DNS group and the DNS group in terms of CO exposure time, Glasgow Coma Scale (GCS), loss of consciousness, creatinine kinase, and troponin I. GCS and NSE were the early predictors of development of DNS. The area under the curve according to the receiver operating characteristic curves of GCS, serum NSE, and GCS combined with serum NSE were 0.922, 0.836, and 0.969, respectively. In conclusion, initial GCS and NSE served as early predictors of development of DNS. Also, NSE might be a useful additional parameter that could improve the prediction accuracy of initial GCS.

Transient degradation of myelin basic protein in the rat hippocampus following acute carbon monoxide poisoning

The neurotoxicity of carbon monoxide (CO) poisoning is a significant clinical problem, but its mechanisms remain unclear. Previous studies of CO-exposed rats showed spatial memory disturbances and degradation of myelin basic protein (MBP) in the brain; however, regional localization of the degradation was not analyzed. In the present study, we histologically determined the foci of CO effects in the hippocampus. Wistar rats were exposed to CO for 60min (1000ppm for 40min+3000ppm for 20min) and returned into room air. For histological evaluation, the animals were sacrificed 90min, 1, 7 and 14 days after CO exposure and the brain tissue was analyzed with hematoxylin-eosin (HE), Nissl and Gallyas myelin staining as well as immunohistochemistry for MBP and phosphorylated or nonphosphorylated neurofilament. No histological changes were observed on HE, Nissl or Gallyas staining. In contrast, we detected MBP reduction at 90min after CO exposure in the dentate gyrus and CA3, and the recovery of MBP was observed after 14 days. The immunoreactivity of neurofilament also changed after CO exposure. Nevertheless, water maze test showed no significant effects of CO exposure on spatial memory. Our findings demonstrate that CO poisoning causes transient degradation of MBP and axonal injury in the hippocampus even though the animals showed no neurological disturbances.

Basal ganglia lesions following carbon monoxide poisoning

PRIMARY OBJECTIVES

Carbon monoxide (CO) is the most common cause of poisoning and may result in basal ganglia lesions. This study reviewed the literature of carbon monoxide poisoning and basal ganglia lesions and prospectively assessed the prevalence of basal ganglia lesions in a cohort of patients with CO poisoning.

RESEARCH DESIGN

Literature review and prospective cohort study.

METHODS

This study conducted a comprehensive review of the literature and assessed 73 CO-poisoned patients for basal ganglia lesions on sequential MR scans. Magnetic resonance scans were obtained on day 1, 2 weeks and 6 months post-CO poisoning.

RESULTS

The literature review found basal ganglia lesions occur in 4-88% of subjects. Only one patient was found with globus pallidus lesions at 2 weeks and 6 months following CO poisoning, that were not present on the initial day 1 MR scan.

CONCLUSIONS

Basal ganglia lesions, including lesions of the globus pallidus, may be less common than previously reported.

Toxicity Associated with Carbon Monoxide

Carbon monoxide is an insidious poison that accounts for thousands of deaths each year in North America. Clinical effects maybe diverse and include headache, dizziness, nausea, vomiting,syn-cope, seizures, coma, dysrhythmias, and cardiac ischemia. Children, pregnant women, and patients who have underlying cardiovascular disease are particularly at risk for adverse out-comes. Treatment consists of oxygen therapy, supportive care, and, in selected cases, hyperbaric oxygen therapy.

Carbon monoxide poisoning

CO is an ubiquitous poison with many sources of exposure. CO poisoning produces diverse signs and symptoms that are often subtle and may be easily misdiagnosed. Failure to diagnose CO poisoning may result insignificant morbidity and mortality and permit continued exposure to a dangerous environment. Treatment of CO poisoning begins with inhalation of supplemental oxygen and aggressive supportive care. HBOT accelerates dissociation of CO from hemoglobin and may also prevent DNS. Absolute indications forHBOT for CO poisoning remain controversial, although most authors would agree that HBOT is indicated in patients who are comatose or neurologically abnormal, have a history of LOC with their exposure, or have cardiac dysfunction. Pregnancy with an elevated CO-Hgb level(>15%-20%) is also widely, considered an indication for treatment.HBOT may be considered in patients who have persistent symptoms despite NBO, metabolic acidosis, abnormalities on neuropsychometric testing, or significantly elevated levels. The ideal regimen of oxygen therapy has yet to be determined, and significant controversy exists regarding HBOTtreatment protocols. Often the local medical toxicologist, poison control center, or hyperbaric unit may assist the treating physician with decisions regarding therapy.

Carbon monoxide poisoning

CO is an insidious poison with many sources of exposure. CO poisoning produces diverse signs and symptoms, which often are subtle and can be misdiagnosed easily. Failure to diagnose CO poisoning may result insignificant morbidity and mortality and allow continued exposure to a dangerous environment. In the ED, a high index of suspicion must be maintained for occult CO exposure. Headache, particularly when associated with certain environments, and flulike illness in the wintertime with symptomatic cohabitants should raise the index of suspicion in the ED significantly for occult CO poisoning. Emergency treatment of CO poisoning begins with inhalation of supplemental oxygen and aggressive supportive care. HBOT accelerates dissociation of CO from hemoglobin and may prevent DNS. Absolute indications for HBOT for CO poisoning remain controversial, although most would agree that HBOT is indicated in patients who are comatose, are neurologically abnormal, have a history of loss of consciousness with their exposure, or have cardiac dysfunction. Pregnancy with an elevated CO-Hgb level (>15-20%) also is widely considered an indication for treatment. HBOT may be considered in patients who have persistent symptoms despite NBO, metabolic acidosis, abnormalities on neuropsychometric testing, or significantly elevated levels. The ideal regimen of oxygen therapy has yet to be determined, and significant controversy exists regarding HBOT protocols. The emergency physician may be confronted with the difficult decision regarding disposition and even transfer to a hyperbaric facility. Often the local medical toxicologist, poison control center, or hyperbaric unit can assist the emergency physician with the decision-making process.

Carbon-monoxide poisoning, behavioural changes and suicide: an unusual industrial accident

We report a case of CO intoxication caused by a motor vehicle's faulty heating-system. A truck driver experienced severe mental deterioration, behavioural changes and delirium after acute CO intoxication and committed suicide 15 months later. This report examines the pathogenetic mechanism of CO, the immediate and delayed consequences of CO intoxication, diagnostic difficulties and current treatment options. The medical-legal aspects of the case are discussed.

Toxicology in the critically ill patient

Intoxications present in many forms including: known drug overdose or toxic exposure, illicit drug use, suicide attempt, accidental exposure, and chemical or biological terrorism. A high index of suspicion and familiarity with toxidromes can lead to early diagnosis and intervention in critically ill, poisoned patients. Despite a paucity of evidence-based information on the management of intoxicated patients, a rational and systematic approach can be life saving.

Statistical parametric mapping in brain single photon computed emission tomography after carbon monoxide intoxication

The purpose of this retrospective study was to assess regional cerebral blood flow in patients after carbon monoxide intoxication by using brain single photon emission computed tomography and statistical parametric mapping. Eight patients with delayed neuropsychiatric sequelae and ten patients with no neuropsychiatric symptoms after carbon monoxide intoxication were studied with brain single photon emission tomography imaging with 99mTc-hexamethyl-propyleneamine oxime. Forty-four control subjects were also studied. We used the adjusted regional cerebral blood flow images in relative flow distribution (normalization of global cerebral blood flow for each subject to 50 ml x 100 g(-1) x min(-1) with proportional scaling) to compare these groups with statistical parametric mapping. Using this technique, significantly decreased regional cerebral blood flow was noted extensively in the bilateral frontal lobes as well as the bilateral insula and a part of the right temporal lobe in the patients with delayed neuropsychiatric sequelae as compared with normal volunteers (P< 0.005). In the patients with no neuropsychiatric symptoms, significantly decreased regional blood flow in the bilateral frontal lobes particularly on the left side was detected. There was a significantly decreased regional cerebral blood flow in the right frontal lobe and insula in the patients with delayed neuropsychiatric sequelae as compared to those with no neuropsychiatric sequelae. It is concluded that statistical parametric mapping is a useful technique for highlighting differences in regional cerebral blood flow in patients following carbon monoxide intoxication as compared with normal volunteers. The selectively reduced blood flow noted in this investigation supports the contention that the decrease following carbon monoxide intoxication may be prolonged and further worsen in the frontal lobe. In addition, the present study may help to clarify the characteristics of the pathophysiological alteration underlying delayed neuropsychiatric sequelae.

Characteristics and outcome of children with carbon monoxide poisoning with and without smoke exposure referred for hyperbaric oxygen therapy

OBJECTIVES

To describe the clinical characteristics and outcome of children with carbon monoxide (CO) poisoning with and without smoke exposure referred for hyperbaric oxygen therapy (HBOT), and to determine the association between any of these characteristics and death.

SETTING

Regional hyperbaric referral center.

PATIENTS

The medical records of 150 children with CO poisoning (COP) who were treated with HBOT between August 92 and September 95 were reviewed.

MEASUREMENTS/MAIN RESULTS

COP was defined as a history of probable exposure to CO, with either a carboxyhemoglobin level (COHb) > 25, or COHb < 25 with neurological, respiratory, or cardiac compromise. Major cutaneous burns were described as second degree burns over greater than 20% of the patient's total body surface area (TBSA), or third degree burns over greater than 10% of the patient's TBSA. Children extracted from a closed-space fire who had airway soot, singed facial hair/facial burns, or respiratory distress were defined as having smoke inhalation and carbon monoxide poisoning (CO/SI). CO/SI occurred in 40.1% of patients. Compared to children with COP alone, those with CO/SI were significantly more likely to have a depressed mental status upon arrival to an ED (76.3 % vs 13.6 %, P < 0.001), lower mean initial GCS (6.7 vs 14.7, P < 0.001), lower mean initial pH (7.2 vs 7.4, P < 0.001), respiratory arrest at the scene (68.5% vs 0%, P < 0.001), and cardiac arrest at the scene (25.9% vs 0%, P < 0.001). Children with CO/SI were significantly more likely to have a poor outcome (death) than children with COP alone (22.6% vs. 0%, P < 0.001). Comparing children with CO/SI who died versus survivors, there were significant differences in mean initial COHb (38.3 vs 24.3, P = 0.03), mean initial temperature upon arrival in an ED (94.9 degrees F vs 98.2 degrees, P < 0.006), respiratory arrest at the scene (92% vs 59.6%, P = 0.04), and cardiac arrest at the scene (66.7% vs 13.5%, P < 0.001). Sixty percent of children died who had a combination of risk factors of smoke inhalation, low temperature, high COHb level, and respiratory and cardiac arrest in the field.

CONCLUSIONS

These preliminary data suggest that children with COP alone who are treated with HBOT are at low risk for dying regardless of initial COHb level. Children with CO/SI have a significantly higher risk of dying than those children with COP alone. A combination of smoke inhalation, low temperature, high COHb level, respiratory arrest, and cardiac arrest is highly associated with death. Prospective studies are needed to confirm and further define these associations.

Use of liver allografts from carbon monoxide poisoned cadaveric donors

Carbon monoxide (CO) inhalation leads to cerebral, cardiac, and, more rarely, liver damage. The use of liver allografts from CO poisoned donors with evidence of liver damage has not previously been reported. In this report we describe two recipients, both in fulminant hepatic failure, who received liver grafts from such donors. One donor had markedly abnormal liver function tests (LFTS), and in the other LFTS were mildly abnormal. In both, the liver appeared normal at procurement. There was satisfactory early function of both allografts, although marked patchy necrosis was seen on the postreperfusion biopsy (case 1), and on a 10 day postoperative biopsy (case 2). In both cases the changes were considered to be related to damage sustained from CO inhalation. Both allografts soon achieved normal function and both recipients are well. We conclude that CO poisoning can cause liver damage that can recover completely following liver transplantation.

Carbon monoxide controversies: neuropsychologic testing, mechanism of toxicity, and hyperbaric oxygen

Recent animal and clinical data require a reevaluation of the traditional approach to the patient exposed to carbon monoxide. Unfortunately, these new data are inconclusive and generate controversies regarding the indications and value of neuropsychologic testing, cause of carbon monoxide toxicity, and indications (if any) for hyperbaric oxygen therapy. These controversies and their implications for the emergency physician are discussed.

Carbon monoxide poisoning and frontal lobe pathology: two case reports and a discussion of the literature

Two patients, a brother and a sister, experienced carbon monoxide (CO) poisoning simultaneously. Both showed deficits in frontal lobe/executive functioning along with mild disturbances in memory and visual-spatial information processing. A review of the literature indicates that frontal lobe deficits are commonly found following CO poisoning along with the 'better-known' deficits in memory and visual-spatial information processing. This type of deficit can affect the personality of the CO-exposed individual and lead to enduring changes in his or her ability to plan, organize and manage activities of daily living.

Benign relapsing meningo-encephalomyelitis

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Acute transient hydrocephalus in carbon monoxide poisoning: a case report

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