Encephaloapthy: a look at 1340 articles .
I did a MedLine search and found 1340 articles written on this diagnosis and I believe it is more common than you think. Our government wastes so much money on other countries problems that I am not going to back down from a RAC without a fight. These Coding Clinics are as out dated as ICD 9 and quite frankly are suspect in clinical accuracy. Actually, the authors state that they take no responsibility for clinical accuracy - it's not what they do.
In my experience I find that Delirium is used synonymously with Encephalopathy mainly by non-neurologists due to the overlap of symptoms. Altered Mental Status and Altered Level of Consciousness are unsophisticated terms frequently documented in hospital charts by both Neurologists and Non Neurologists to describe a general alteration in brain function. It is very important to look at these charts closely due to the controversy surrounding the potential for diagnosis of Encephalopathy. The catchall term “Toxic Metabolic Encephalopathy" is used by too many physicians regardless of the specific underlying etiology in a fashion similar to the Cardiologists who use the catchall term Acute Coronary Syndrome.
First of all, we must have a consistent definition of the intent of the ICD codes for encephalopathy. It's supposed to be alteration of function of the brain due to nontraumatic processes, nonphysical processes that don't have an alternative term that has a specific meaning. For example, coma is coma. It may be an encephalopathic process, but it has a name already and you don't double dip. Well demonstrative of this is hepatic coma which is designated as an alternative term for hepatic encephalopathy. It's in the code books. We may have an infectious encephalopathy caused by Lyme disease but mumps encephalitis is an infectious encephalopathy that already has a different name - you don't double dip. And rather than being an intentional, transient process due to external sources that will resolve, encephalopathies are conditions with potential for severe brain destruction if not reversed. Getting drunk on alcohol is getting drunk on alcohol. Alcoholic encephalopathy has to do with such long term use of alcohol in sufficient volumes that vitamin B deficiency affects brain function long term. Similarly the effects of sedatives are called sedation and not encephalopathy - unless the patient has been on such long term use in such high quantities that the brain function suffers even when the drug wears off.
Next is to recognize that there is no such thing as toxic metabolic encephalopathy. Thank goodness this is corrected in ICD-10. Metabolic encephalopathies are caused by chemicals affecting the brain that are created in the body as uremic encephalopathy and the so-called septic encephalopathy and toxic encephalopathies are due to substances taken into the body, such as lead encephalopathy or bromide encephalopathy. Then we have genetic encephalopathies and infectious encephalopathies and hypoxic encephalopathies and others.
The time course of development of the encephalopathy can vary from rapid to the more common subacute presentation from insidiously developing systemic metabolic processes.
I may suspect a Metabolic encephalopathy when there is an altered cognitive status in the absence of focal neurologic signs or an obvious anatomic lesion such as an acute CVA or head injury. The altered mental status observed can start as mild confusion with intermittent disorientation to person, time, or place and difficulty attending to questions or tasks at hand. Delirium, which may be a manifestation of encephalopathy but may very well be a manifestation of Alzheimer's disease or psychiatric state, is a further change toward heightened arousal alternating with somnolence, often worse at night and fluctuating throughout the day. Finally, progression to lethargy, a state of sleepiness in which the person is difficult to arouse by vigorous stimulation, can lead into stupor or coma as unconsciousness ensues. This sequence of events may even be punctuated by focal or generalized tonic-clonic seizures and postictal somnolence as part of the overall clinical picture. (Hypoxemia, Hypoglycemia) Oxygen and Glucose are critical neuronal energy substrates and a low level of either of these will lead to irreversible neuronal death unless recognized and reversed quickly; most other metabolic disorders are less likely to directly lead (or lead quickly) to neuronal cell death and irreversible injury. Likewise, profound Hypotension or Anemia can lead to loss of energy supply to neurons. In addition to hypoxemia and hypoglycemia, encephalopathy frequently occurs in the setting of Hyperglycemia and of certain electrolyte abnormalities, especially Hyponatremia, Hypernatremia, and Hypercalcemia.
Medication-Related transient brain functional changes with central nervous system effects, including sedatives, analgesics, anticholinergics, anticonvulsants, anxiolytics, and any of the wide variety of CNS active drugs, are well recognized. However, several medications in current clinical use have been relatively recently associated with specific and distinctive toxic syndromes. Ifosfamide (used in Prostate Ca ) and Cefepime and Metronidazole are commonly associated with encephalopathic syndromes.
Posterior Reversible Encephalopathy Syndrome
This is an increasingly recognized clinical syndrome, although controversially named since it does not always involve posterior brain regions and is not always completely reversible. The posterior reversible encephalopathy syndrome typically presents clinically with encephalopathy, visual disturbances (due to cortical visual dysfunction), and seizures, usually in association with elevated systemic blood pressure. It has a name - it has a code - don't double dip.
Thiamine Deficiency (Wernicke’s Encephalopathy)
Deficiency of thiamine causes Wernicke’s encephalopathy, characterized classically by the clinical triad of ophthalmoplegia, mental status changes, and ataxia. This is a very important cause of encephalopathy due to the potential irreversibility of clinical findings, and especially because of the development of an irreversible amnestic state, if thiamine deficiency is not recognized and treated emergently . Although commonly thought of as a disease of alcoholics, Wernicke’s encephalopathy can occur due to any process that leads to inadequate absorption of thiamine, including hyperemesis states such as hyperemesis gravidarum, malnutrition from any cause, bariatric surgery, chronic diarrheal illnesses, and in the course of many systemic illnesses.
Severe Systemic Illness and Septic Encephalopathy
Encephalopathy in the clinical setting of systemic sepsis, with or without multiorgan failure, has led to the designation of a septic encephalopathy. The theoretical mechanisms for this syndrome include the effects of inflammatory mediators, blood–brain barrier dysfunction, and other possible metabolic effects of the severe systemic dysfunction.
Hepatic Encephalopathy
Hepatic encephalopathy can occur in patients with either chronic liver disease (cirrhosis) or acute liver failure. Ammonia levels remain helpful in the clinical diagnosis of hepatic encephalopathy,although these levels do not correlate well with the various stages of encephalopathy, and a normal serum ammonia level does not exclude the diagnosis of hepatic encephalopathy.
Uremic Encephalopathy
Encephalopathy can occur due to either acute or chronic renal failure, and typically develops more rapidly in patients with acute kidney dysfunction . Symptoms of uremic encephalopathy include asterixis, myoclonus (uremic twitching), and coarse tremor; seizures may also be seen. The clinical symptoms and sign mimic those of many other metabolic encephalopathies; however, the tremulousness and twitching seen in many patients with uremic encephalopathy, although not very specific, may be somewhat more suggestive of this cause of encephalopathy compared to other systemic processes. Other systemic causes of alteration of brain function that especially need to be considered in the uremic patient include drug toxicities (especially those that are renally metabolized or excreted), electrolyte disturbances, and thiamine deficiency.
Pancreatic Encephalopathy
The term “pancreatic encephalopathy†was coined in 1941 to describe the known association between acute pancreatitis and a severe diffuse encephalopathy. Pancreatic encephalopathy typically has been reported to occur within 2 weeks of pancreatitis onset, especially between the second and fifth days, with varying incidences (up to as high as 35%) reported. The diagnosis of pancreatic encephalopathy should be considered in any patient with a diffuse encephalopathy occurring in the setting of acute pancreatitis. The pathogenesis of pancreatic encephalopathy has been proposed to relate to blood–brain barrier breakdown as a consequence of activation of phospholipase A and conversion of lecithin into its hemolytic form, although fat embolism is another putative mechanism. Patients with pancreatitis are also at risk for the development of Wernicke’s encephalopathy, which should strongly be considered in the differential diagnosis, or as an additional comorbid process, in these patients.
Fat Embolism - often a variety of anoxic brain damage or anoxic encephalopathy
Fat embolism should be considered among the potential emergent diagnoses of any patient presenting with a diffuse encephalopathy in characteristic clinical settings, such as after recent orthopedic procedures or trauma. The fat embolism syndrome is characterized by the classic clinical triad of encephalopathy, pulmonary dysfunction, and a petechial rash. Although most commonly associated with long-bone trauma, fat embolism also occurs in a variety of other scenarios, including acute pancreatitis, diabetes mellitus, burns, joint reconstruction, liposuction, cardiopulmonary bypass, decompression sickness, and parenteral lipid infusion. Clinical symptoms of fat embolism typically, though not invariably, occur 24–48 h after the inciting event. The primary neurologic manifestation of fat embolism is a diffuse encephalopathy, though focal neurologic signs and seizures can occur. In some patients, the neurologic manifestations may be the sole clinical feature; however, pulmonary symptoms are typically present and these symptoms may range from mild dyspnea to tachypnea to respiratory failure. The finding of petechiae on the skin completes the clinical triad, but this is seen in only about half of patients with the syndrome. MRI in some patients has shown multifocal punctate DWI-positive white matter lesions consistent with multifocal embolic lesions. The mechanical theory proposes that bone marrow contents enter the lungs via the venous system, where they may also gain access to the systemic circulation and enter the brain via pulmonary arteriovenous shunts or patent foramen ovale. The biochemical theory proposes that pulmonary abnormalities result from a toxic effect on lung cells by circulating free fatty acids. These theories are not mutually exclusive and both mechanisms may be responsible for various aspects of the clinical syndrome. The possibility of fat embolism should be considered in any patient with encephalopathy occurring in the appropriate clinical context, especially if other causes have been excluded.
Hugh Stephenson RN,RCIS,CCRN Alumnus,CCDS
REF:
Riggs JE. Neurologic manifestations of electrolyte disturbances.
Neurol. Clin. 2002;20(1):227–239.
Girard TD, Pandharipande PP, Ely EW. Delirium in the intensive care unit. Crit. Care 2008;12(3):1–9.
Mori F, et al. Hypoglycemic encephalopathy with extensive lesions in the cerebral white matter. Neuropathology 2006;26:147–152.
Lee VH, et al. Clinical spectrum of reversible posterior leukoencephalopathy syndrome. Arch. Neurol. 2008;65 (2):205–210.
Munoz, Santiago J. Hepatic encephalopathy. Med. Clin. N. Am. 2008;92:795–812
Brouns R, De Deyn P.P. Neurological complications in renal failure: a review. Clin. Neurol. Neurosurg. 2004;107:1–16.
Hufner K, et al. Fat embolism syndrome as a neurologic emergency. Arch Neurol. 2008;65(8):1124–1125
In my experience I find that Delirium is used synonymously with Encephalopathy mainly by non-neurologists due to the overlap of symptoms. Altered Mental Status and Altered Level of Consciousness are unsophisticated terms frequently documented in hospital charts by both Neurologists and Non Neurologists to describe a general alteration in brain function. It is very important to look at these charts closely due to the controversy surrounding the potential for diagnosis of Encephalopathy. The catchall term “Toxic Metabolic Encephalopathy" is used by too many physicians regardless of the specific underlying etiology in a fashion similar to the Cardiologists who use the catchall term Acute Coronary Syndrome.
First of all, we must have a consistent definition of the intent of the ICD codes for encephalopathy. It's supposed to be alteration of function of the brain due to nontraumatic processes, nonphysical processes that don't have an alternative term that has a specific meaning. For example, coma is coma. It may be an encephalopathic process, but it has a name already and you don't double dip. Well demonstrative of this is hepatic coma which is designated as an alternative term for hepatic encephalopathy. It's in the code books. We may have an infectious encephalopathy caused by Lyme disease but mumps encephalitis is an infectious encephalopathy that already has a different name - you don't double dip. And rather than being an intentional, transient process due to external sources that will resolve, encephalopathies are conditions with potential for severe brain destruction if not reversed. Getting drunk on alcohol is getting drunk on alcohol. Alcoholic encephalopathy has to do with such long term use of alcohol in sufficient volumes that vitamin B deficiency affects brain function long term. Similarly the effects of sedatives are called sedation and not encephalopathy - unless the patient has been on such long term use in such high quantities that the brain function suffers even when the drug wears off.
Next is to recognize that there is no such thing as toxic metabolic encephalopathy. Thank goodness this is corrected in ICD-10. Metabolic encephalopathies are caused by chemicals affecting the brain that are created in the body as uremic encephalopathy and the so-called septic encephalopathy and toxic encephalopathies are due to substances taken into the body, such as lead encephalopathy or bromide encephalopathy. Then we have genetic encephalopathies and infectious encephalopathies and hypoxic encephalopathies and others.
The time course of development of the encephalopathy can vary from rapid to the more common subacute presentation from insidiously developing systemic metabolic processes.
I may suspect a Metabolic encephalopathy when there is an altered cognitive status in the absence of focal neurologic signs or an obvious anatomic lesion such as an acute CVA or head injury. The altered mental status observed can start as mild confusion with intermittent disorientation to person, time, or place and difficulty attending to questions or tasks at hand. Delirium, which may be a manifestation of encephalopathy but may very well be a manifestation of Alzheimer's disease or psychiatric state, is a further change toward heightened arousal alternating with somnolence, often worse at night and fluctuating throughout the day. Finally, progression to lethargy, a state of sleepiness in which the person is difficult to arouse by vigorous stimulation, can lead into stupor or coma as unconsciousness ensues. This sequence of events may even be punctuated by focal or generalized tonic-clonic seizures and postictal somnolence as part of the overall clinical picture. (Hypoxemia, Hypoglycemia) Oxygen and Glucose are critical neuronal energy substrates and a low level of either of these will lead to irreversible neuronal death unless recognized and reversed quickly; most other metabolic disorders are less likely to directly lead (or lead quickly) to neuronal cell death and irreversible injury. Likewise, profound Hypotension or Anemia can lead to loss of energy supply to neurons. In addition to hypoxemia and hypoglycemia, encephalopathy frequently occurs in the setting of Hyperglycemia and of certain electrolyte abnormalities, especially Hyponatremia, Hypernatremia, and Hypercalcemia.
Medication-Related transient brain functional changes with central nervous system effects, including sedatives, analgesics, anticholinergics, anticonvulsants, anxiolytics, and any of the wide variety of CNS active drugs, are well recognized. However, several medications in current clinical use have been relatively recently associated with specific and distinctive toxic syndromes. Ifosfamide (used in Prostate Ca ) and Cefepime and Metronidazole are commonly associated with encephalopathic syndromes.
Posterior Reversible Encephalopathy Syndrome
This is an increasingly recognized clinical syndrome, although controversially named since it does not always involve posterior brain regions and is not always completely reversible. The posterior reversible encephalopathy syndrome typically presents clinically with encephalopathy, visual disturbances (due to cortical visual dysfunction), and seizures, usually in association with elevated systemic blood pressure. It has a name - it has a code - don't double dip.
Thiamine Deficiency (Wernicke’s Encephalopathy)
Deficiency of thiamine causes Wernicke’s encephalopathy, characterized classically by the clinical triad of ophthalmoplegia, mental status changes, and ataxia. This is a very important cause of encephalopathy due to the potential irreversibility of clinical findings, and especially because of the development of an irreversible amnestic state, if thiamine deficiency is not recognized and treated emergently . Although commonly thought of as a disease of alcoholics, Wernicke’s encephalopathy can occur due to any process that leads to inadequate absorption of thiamine, including hyperemesis states such as hyperemesis gravidarum, malnutrition from any cause, bariatric surgery, chronic diarrheal illnesses, and in the course of many systemic illnesses.
Severe Systemic Illness and Septic Encephalopathy
Encephalopathy in the clinical setting of systemic sepsis, with or without multiorgan failure, has led to the designation of a septic encephalopathy. The theoretical mechanisms for this syndrome include the effects of inflammatory mediators, blood–brain barrier dysfunction, and other possible metabolic effects of the severe systemic dysfunction.
Hepatic Encephalopathy
Hepatic encephalopathy can occur in patients with either chronic liver disease (cirrhosis) or acute liver failure. Ammonia levels remain helpful in the clinical diagnosis of hepatic encephalopathy,although these levels do not correlate well with the various stages of encephalopathy, and a normal serum ammonia level does not exclude the diagnosis of hepatic encephalopathy.
Uremic Encephalopathy
Encephalopathy can occur due to either acute or chronic renal failure, and typically develops more rapidly in patients with acute kidney dysfunction . Symptoms of uremic encephalopathy include asterixis, myoclonus (uremic twitching), and coarse tremor; seizures may also be seen. The clinical symptoms and sign mimic those of many other metabolic encephalopathies; however, the tremulousness and twitching seen in many patients with uremic encephalopathy, although not very specific, may be somewhat more suggestive of this cause of encephalopathy compared to other systemic processes. Other systemic causes of alteration of brain function that especially need to be considered in the uremic patient include drug toxicities (especially those that are renally metabolized or excreted), electrolyte disturbances, and thiamine deficiency.
Pancreatic Encephalopathy
The term “pancreatic encephalopathy†was coined in 1941 to describe the known association between acute pancreatitis and a severe diffuse encephalopathy. Pancreatic encephalopathy typically has been reported to occur within 2 weeks of pancreatitis onset, especially between the second and fifth days, with varying incidences (up to as high as 35%) reported. The diagnosis of pancreatic encephalopathy should be considered in any patient with a diffuse encephalopathy occurring in the setting of acute pancreatitis. The pathogenesis of pancreatic encephalopathy has been proposed to relate to blood–brain barrier breakdown as a consequence of activation of phospholipase A and conversion of lecithin into its hemolytic form, although fat embolism is another putative mechanism. Patients with pancreatitis are also at risk for the development of Wernicke’s encephalopathy, which should strongly be considered in the differential diagnosis, or as an additional comorbid process, in these patients.
Fat Embolism - often a variety of anoxic brain damage or anoxic encephalopathy
Fat embolism should be considered among the potential emergent diagnoses of any patient presenting with a diffuse encephalopathy in characteristic clinical settings, such as after recent orthopedic procedures or trauma. The fat embolism syndrome is characterized by the classic clinical triad of encephalopathy, pulmonary dysfunction, and a petechial rash. Although most commonly associated with long-bone trauma, fat embolism also occurs in a variety of other scenarios, including acute pancreatitis, diabetes mellitus, burns, joint reconstruction, liposuction, cardiopulmonary bypass, decompression sickness, and parenteral lipid infusion. Clinical symptoms of fat embolism typically, though not invariably, occur 24–48 h after the inciting event. The primary neurologic manifestation of fat embolism is a diffuse encephalopathy, though focal neurologic signs and seizures can occur. In some patients, the neurologic manifestations may be the sole clinical feature; however, pulmonary symptoms are typically present and these symptoms may range from mild dyspnea to tachypnea to respiratory failure. The finding of petechiae on the skin completes the clinical triad, but this is seen in only about half of patients with the syndrome. MRI in some patients has shown multifocal punctate DWI-positive white matter lesions consistent with multifocal embolic lesions. The mechanical theory proposes that bone marrow contents enter the lungs via the venous system, where they may also gain access to the systemic circulation and enter the brain via pulmonary arteriovenous shunts or patent foramen ovale. The biochemical theory proposes that pulmonary abnormalities result from a toxic effect on lung cells by circulating free fatty acids. These theories are not mutually exclusive and both mechanisms may be responsible for various aspects of the clinical syndrome. The possibility of fat embolism should be considered in any patient with encephalopathy occurring in the appropriate clinical context, especially if other causes have been excluded.
Hugh Stephenson RN,RCIS,CCRN Alumnus,CCDS
REF:
Riggs JE. Neurologic manifestations of electrolyte disturbances.
Neurol. Clin. 2002;20(1):227–239.
Girard TD, Pandharipande PP, Ely EW. Delirium in the intensive care unit. Crit. Care 2008;12(3):1–9.
Mori F, et al. Hypoglycemic encephalopathy with extensive lesions in the cerebral white matter. Neuropathology 2006;26:147–152.
Lee VH, et al. Clinical spectrum of reversible posterior leukoencephalopathy syndrome. Arch. Neurol. 2008;65 (2):205–210.
Munoz, Santiago J. Hepatic encephalopathy. Med. Clin. N. Am. 2008;92:795–812
Brouns R, De Deyn P.P. Neurological complications in renal failure: a review. Clin. Neurol. Neurosurg. 2004;107:1–16.
Hufner K, et al. Fat embolism syndrome as a neurologic emergency. Arch Neurol. 2008;65(8):1124–1125