UMEM Educational Pearls - By Aisha Liferidge

Title: Transient Global Amnesia

Category: Neurology

Keywords: amnesia, TIA, memory (PubMed Search)

Posted: 9/5/2007 by Aisha Liferidge, MD (Updated: 11/21/2024)
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Transient Global Amnesia (TGA) is a rare (5 to 11 cases per 100,000 persons per year), but clinically well-defined disorder defined as an acute episode of short-term memory loss, in the absence of any neurologic signs or symptoms, which resolves within 24 hours. TGA is typically triggered by an event such as valsalva, exercise, emotional stress, sexual intercourse, immersion in cold water, painful stimuli, and severe exertion. While there are widely used diagnostic criteria, TGA is primarily a clinical diagnosis and one of exclusion. While TGA is benign, self-limiting, and there is no specific treatment other than reassurance, it is important to recognize and differentiate TGA from TIA, which has different prognostic implications. Agrawal, et al. "Transient Global Amnesia: An Uncommon Differential Diagnosis of Transient Ischemic Attack." Hospital Physician 43:8.

Title: Cheyne Stokes Respirations

Category: Neurology

Keywords: Cheyne Stokes, stroke, increased intracranial pressure (PubMed Search)

Posted: 8/29/2007 by Aisha Liferidge, MD (Updated: 11/21/2024)
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Cheyne-Stokes (CS) respirations, also known as "periodic breathing," results from the inability of the respiratory center of the brain, the brain stem (i.e. pons and medulla oblongata), to rapidly compensate for changing serum partial pressure of oxygen and carbon dioxide. CS is characterized by respirations of gradually increasing and decreasing tidal volumes, with interspersed periods of apnea. Conditions associated with CS: - Increased ICP (i.e. space occupying brain lesions such as hemorrhage and tumors) - Congestive heart failure - Altitude sickness - Toxic-metabolic encephalopathy - Carbon monoxide poisoning - High-dose morphine administration CS was first described by physicians John Cheyne and William Stokes. Wikipedia Encyclopedia. The Diagnosis of Stupor and Coma by Plum and Posner.

Title: Cushings Reflex and Triad

Category: Neurology

Keywords: increased intracranial pressure, cushings triad, cushings reflex, intracranial hemorrhage (PubMed Search)

Posted: 8/22/2007 by Aisha Liferidge, MD (Updated: 11/21/2024)
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Cushings reflex = a hypothalamic response to brain ischemia wherein the sympathetic nervous system is activated which causes increased peripheral vascular resistance with a subsequent increase in BP. The increased BP then activates the parasympathetic nervous system via carotid artery baroreceptors, resulting in vagal-induced bradycardia. The brain ischemia that leads to cushings reflex is usually due to the poor perfusion that results from increased ICP due to head bleeds or mass lesions. Cushings reflex leads to the clinical manifestation of Cushings triad. Cushings triad = hypertension, bradycardia, and irregular respirations (Cheyne-Stokes breathing). Some sources describe widened pulse pressure (increasing difference between systolic and diastolic BP) as the 3rd component of the triad, rather than irregular respirations. Cushings triad signals impending danger of brain herniation, and thus, the need for decompression. Consider administering mannitol, hyperventilation, and elevation of the head of bed as temporizing measures. Cushings triad was first described in 1902 by Harvey Williams Cushing, an American neurosurgeon. -Physiology, 2nd Edition, Saunders, 2002, page 150. -Ayling, J (2002). "Managing head injuries". Emergency Medical Services31 (8): 42.

Title: Coagulation Disorders Causing Ischemic Stroke

Category: Neurology

Keywords: coagulopathy, stroke (PubMed Search)

Posted: 8/15/2007 by Aisha Liferidge, MD (Updated: 11/21/2024)
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-polycythemia rubra vera -sickle cell disease -essential thrombocytosis - TTP - Heparin-induced thrombocytopenia -Antithrombin III deficiency - Protein C or S deficiency - Factors V, VII, XII, or XIII deficiency -heparin cofactor II deficiency - dysfibrinogenemias -antiphospholipid/anticardiolipin antibodies -nephrotic syndrome -malignancy -pregnancy -oral contraceptives -dehydration

Title: TIA

Category: Neurology

Keywords: TIA, stroke (PubMed Search)

Posted: 8/8/2007 by Aisha Liferidge, MD (Updated: 11/21/2024)
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While TIA has historically been defined as lasting less than 24 hours, recent data clearly demonstrates that ischemic attack lasting longer than one hour is often associated with actual brain infarction. Most TIA's last less than 5 minutes. Evidence of acute infarction can be identified by MRI in up to 50% of patients who meet the 24 hour criteria for TIA. Diffusion MRI in patients with transient ischemic attacks. Kidwell CS; Alger JR; Di Salle F; Starkman S; Villablanca P; Bentson J; Saver JL. Stroke 1999, Jun;30(6):1174-80. Transient ischemic attack--proposal for a new definition. Albers GW; Caplan LR; Easton JD; Fayad PB; Mohr JP; Saver JL; Sherman DG. New England Journal of Medicine 2002, Nov 21;347(21):1713-6.

Title: Stroke Mimics

Category: Neurology

Keywords: stroke, stroke mimics, complex migraine (PubMed Search)

Posted: 8/1/2007 by Aisha Liferidge, MD (Updated: 11/21/2024)
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One study found that the top 4 stroke mimics confused for a true stroke are: 1) Unrecognized seizure with post-ictal phase 2) Systemic infections 3) Brain tumor 4) Metabolic disturbances Complex migraine, specifically hemiplegic migraine, is also a common stroke mimic. This diagnosis is especially difficult to make on initial presentation and should be a diagnosis of exclusion. The hemiparesis associated with the migraine can actually outlast the actual headache. Libman RB, Wirkowski E, Alvir J, Rao TH. Conditions that mimic stroke in the emergency department. Implications for acute stroke trials. Archives of Neurology. 1995;52:1119-1122.