eMedicine Specialties > Neurology > Behavioral Neurology and Dementia

Uremic Encephalopathy: Differential Diagnoses & Workup

Author: Gabriel Bucurescu, MD, MS, Staff Neurologist, Neurology Service, Philadelphia Veterans Affairs Medical Center
Contributor Information and Disclosures

Updated: Dec 9, 2008

Differential Diagnoses

Alzheimer Disease
Huntington Disease
Alzheimer Disease in Individuals With Down Syndrome
Intracranial Hemorrhage
Aphasia
Normal Pressure Hydrocephalus
Apraxia and Related Syndromes
Pick Disease
Complex Partial Seizures
Status Epilepticus
Dementia in Motor Neuron Disease
Subdural Hematoma
Dementia With Lewy Bodies
Tonic-Clonic Seizures
EEG in Dementia and Encephalopathy
Transient Global Amnesia
EEG in Status Epilepticus
Frontal and Temporal Lobe Dementia
Generalized EEG Waveform Abnormalities

Other Problems to Be Considered

Dementia
Complex partial status epilepticus
Dementia in Huntington disease
Dementia in Parkinson disease
Dementia in progressive supranuclear palsy
Epileptic encephalopathies
Vascular dementia
EEG in coma
Tonic seizures

Workup

Laboratory Studies

  • Blood tests reveal electrolyte abnormalities and abnormal renal function. PTH and calcium levels are high.
  • Results of routine CSF studies tend to be normal.

Imaging Studies

  • Brain imaging is of limited value.
  • CT and MRI studies typically show cerebral atrophy and secondary ventricular dilatation.
    • These studies are valuable for excluding intracranial hemorrhage and subdural hematoma when patients have an acute change in mental status.
    • Case reports have documented increased signal intensity in the cortical and subcortical areas of the parietal and occipital lobes. These findings are thought to reflect local edema that resolved after dialysis treatments. Improvement on MRI has been correlated with improved serum creatinine and BUN levels.

Other Tests

  • EEG (especially serial EEG) is useful in assessing patients and in monitoring their progress.
    • The EEG is generally abnormal, showing generalized slowing that becomes more severe as the condition worsens.
    • In acute uremia, EEG is characterized by irregular low voltage with slowing of the posterior dominant alpha rhythm and occasional theta bursts. Characteristic findings are prolonged bursts of bilateral, synchronous slow and sharp waves or spike and waves.
    • Bilateral spike discharges may be associated with myoclonic jerks. Generalized or partial seizures may be observed.
    • After dialysis begins, EEG may worsen for up to 6 months before slowly normalizing as renal function improves. Dialysis itself tends not to affect the EEG.
    • In chronic uremia, the EEG stabilizes during long-term dialysis treatment. When changes occur during periods of deterioration corresponding to fluctuations in blood urea levels, the findings include diffuse delta and theta activity, generalized spike-wave activity, and heightened sensitivity to photic stimulation.
    • Quantitative EEG using real-time brain mapping computer-aided topographical electroencephalometry (CATEEM) technology has been shown to be useful in monitoring mental impairment and may serve as a control for monitoring therapeutic intervention.3  
    • Sleep EEG may show long bursts of high voltage (12-13 waves per second with enhanced vertex sharp activity in drowsiness), lack of spindles (14/s) in stage 2 sleep, and prolonged high-voltage, slow bursts with awakening.
  • Evoked-potential studies are of limited value, revealing only nonspecific changes or normal patterns.
    • Visual evoked potentials (VEPs): Studies may reveal no change before or after dialysis, or P100 may be absent or delayed. This abnormality is attributed to a circulating renal factor, which has a toxic effect on the papillomacular bundle or on demyelination. No relationship with BUN is known.
    • Brainstem auditory evoked potentials (BAEPs): Some studies of patients with UE show no abnormalities in BAEPs, whereas other studies of small numbers of patients revealed abnormalities, especially in the III-IV latencies. The abnormalities reversed with dialysis in some patients and did not reverse in others. Changes in BAEP were attributed to either toxic substances or demyelination. Other studies measuring the P300 latency and amplitude have shown improvement in patients with UE who were specifically treated for anemia. The improvement in the electrophysiological parameters accompanied improvement in cognitive function, suggesting that measurements of P300 may serve as an measurable marker for cognitive function.4
    • Somatosensory evoked potentials (SEPs): Studies may show delayed sensory conduction in the peripheral nerve in patients with no symptoms of neuropathy. This was observed in the upper limb with electrically and mechanically evoked SEPs.
      • In 1 study, electrical stimulation of the ulnar nerve at the wrist showed abnormal conduction between the brachial plexus and the spinal cord and lower medulla. Other studies revealed abnormal conduction between the lower medulla and the thalamus and cortex.
      • Mechanical stimulation of the fingers showed abnormalities in the spinal cord to thalamus-cortex segment, whereas electrical stimulation did not.
      • Some studies revealed central delays and increased amplitudes in patients with chronic uremia, whereas others showed normal central conduction times in patients undergoing hemodialysis.
      • Abnormalities were observed in both upper- and lower-limb SEPs in patients with chronic renal failure.

Procedures

  • Hemodialysis
  • Peritoneal dialysis
  • Renal transplantation
  • Neurosurgical intervention for intracranial hemorrhage or subdural hematoma

Histologic Findings

Brain histologic findings in UE include meningeal fibrosis, glial changes, edema, vascular degeneration, focal and diffuse neuronal degeneration, and focal demyelination. Small infarcts are also seen and are probably due to hypertension or focal necrosis. Cerebellar acute granule cell necrosis is observed.

Patients with dialysis dementia have spongiform changes in the outer 3 cortical layers, with elevated aluminum levels in the cerebral cortex. Other changes include neuronal loss, accumulation of lipofuscin pigment, and neurofibrillary degeneration in the motor cortex and in the red, dentate, and olivary nuclei.

More on Uremic Encephalopathy

Overview: Uremic Encephalopathy
Differential Diagnoses & Workup: Uremic Encephalopathy
Treatment & Medication: Uremic Encephalopathy
Follow-up: Uremic Encephalopathy
Multimedia: Uremic Encephalopathy
References
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Further Reading

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Keywords

encephalopathy, renal failure, wernicke encephalopathy, hepatic encephalopathy, uremic state, uremia, uremic coma, uremic dementia, dialysis encephalopathy, uremic encephalopathy, UE, dialysis dementia, dialysis disequilibrium syndrome, RF, end-stage renal disease, ESRD, progressive renal insufficiency, multiorgan failure

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Contributor Information and Disclosures

Author

Gabriel Bucurescu, MD, MS, Staff Neurologist, Neurology Service, Philadelphia Veterans Affairs Medical Center
Gabriel Bucurescu, MD, MS is a member of the following medical societies: American Academy of Neurology, American Clinical Neurophysiology Society, and American Epilepsy Society
Disclosure: Nothing to disclose.

Medical Editor

J Stephen Huff, MD, Associate Professor, Emergency Medicine and Neurology, Department of Emergency Medicine, University of Virginia Health Sciences Center
J Stephen Huff, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Neurology, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Richard J Caselli, MD, Professor, Department of Neurology, Mayo Medical School, Rochester, MN; Chair, Department of Neurology, Mayo Clinic of Scottsdale
Richard J Caselli, MD is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Medical Association, American Neurological Association, and Sigma Xi
Disclosure: Nothing to disclose.

CME Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital
Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Howard A Crystal, MD, Professor, Departments of Neurology and Pathology, State University of New York Downstate; Consulting Staff, Department of Neurology, University Hospital and Kings County Hospital Center
Howard A Crystal, MD is a member of the following medical societies: American Academy of Neurology and American Neurological Association
Disclosure: Pfizer Honoraria Speaking and teaching; Myriad Honoraria Consulting

 
 
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