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5 CNS: Demy-Neuromus
Step Up to Medicine, Chap 5: Demyelinating Dz, Neoplasms, Trauma, Neuromusc Dz
| Question | Answer |
|---|---|
| Clinical definition of definite MS? | 2 episodes of sx (transient sensory deficits, fatigue, weakness/spasticity, visual disturbances, incontinence, neuropathic pain) + evidence of 2 white matter lesions (imaging or clinical) |
| Lab-supported definition of definite MS? | 2 episodes of sx + evidence of 1 white matter lesion on MRI + abnormal CSF (oligoclonal IgG bands in CSF) |
| Definition of probable MS? | 2 episodes of sx + 1 white matter lesion or oligoclonal IgG bands in CSF |
| Classic location of demyelination (plaques) in MS? | Angles of lateral ventricles |
| What is internuclear ophthalmoplegia? A lesion in which area leads to this deficit? | ipsilateral medial rectus palsy (unable to adduct eye on lateral gaza) and horizontal nystagmus of abducting eye (contralateral to side of lesion); lesion is in medial longitudinal fasciculous |
| Tx for acute MS attacks? | High dose IV corticosteroids. Tx does not alter course, however. |
| Disease modifying therapy for MS? | Interferon therapy (start early in course b/f disability becomes irreversible) and immunosuppressives like cyclophosphamide (reserved for rapidly progressive dz due to toxic SE) |
| Symptomatic therapy for MS? | Baclofen for m spasticity and carbamazepine or gabapentin for neuropathic pain |
| Guillan Barre is typically preceded by what type of event? | A viral or mycoplasma infection of the upper respiratory or GI tract |
| Usual 3 causes of death in Guillan Barre? | Respiratory failure, pneumonia, or arrhythmias |
| How do you diagnose Guillan Barre? | CSF analysis shows elevated protein with normal cell ct and EMG shows decreased motor nerve conduction velocity. If suspected, ADMIT PT IMMEDIATELY for observation. |
| Tx for Guillan Barre? Which drug should never be given? | Tx: IV immunoglobulin for significant weakness with plasmapheresis if weakness progresses, mechanical ventilation if necessary. NEVER GIVE STEROIDS! |
| MC intracranial neoplasms? | Brain mets |
| Name 2 important indications for ordering an MRI to rule out an intracranial mass. | 1. New-onset seizure in an adult 2. New and persistent or progressive headache |
| Specific risk of radiation therapy in intracranial neoplasms? | May cause new primary tumors such as meningiomas |
| MC primary CNS neoplasms in adults? | astrocytomas |
| Primary lymphomas are seen in which pt populations? | Immunosuppressed, esp AIDS and transplant recipients |
| 5 MC primary sites of mets to brain (in order of frequency)? | 1. Lung (MC) 2. Breast 3. Skin (melanoma) 4. Kidney 5. GI tract |
| Ddx of a ring-enhancing brain lesion? | Metastatic cancer, brain abscess, glio, lymphoma, and toxoplasmosis |
| CSF findings in meningeal carcinomatosis (mets to meninges, usually via bloodstream)? | Malignant cells, elevated protein and lymphocytes, and decreased glucose |
| Bilateral Schwannomas are pathognomonic for what disease? | Neurofibromatosis, type II |
| 3 determinants of intracranial pressure? | Volume of brain, volume of blood, volume of CSF |
| MCC death after a severe head injury? | Elevated ICP (normal is 5-15; anything over 20 is worrisome) |
| What ophthalmologic finding suggests elevated ICP? | Bilateral fixed and dilated pupils |
| 4 signs of basilar skull fracture? | 1. Raccoon eyes (periorbital ecchymoses) 2. Battle's sign (postauricular ecchymoses) 3. Hemotympanum 4. CSF rhinorrhea/otorrhea |
| What is a coup injury? | Injury at site of impact (contrecoup is injury at site opposite the point of impact) |
| What is the normal cerebral perfusion pressure? What happens if ICP increases to the level of MAP? | >50 is normal. If ICP increases to level of MAP, cerebral perfusion pressure is lost and brain cell death ensues. |
| ICU pressure goal for head trauma pts? | MAP >80 and ICP <20. Ensures cerebral perfusion pressure of at least 60. |
| What is Cushing's triad? What does it signify? | Triad is hypertension, bradycardia, and respiratory irregularity seen in response to increased ICP. Signifies life-threatening levels of ICP. |
| Most important regulator of cerebral vessel dilation? | PaCO2. Increase PaCO2 causes cerebral vasodilation. |
| Techniques for lowering ICP? | Reverse Trendelenburg (raise head of bed), intubation + hyperventilation, maintain PaCO2 30-35, mannitol, narcotics (morphine or fentanyl), neuromusc paralysis (vencuronium or pancuronium), lower body temp, drain CSF with ventricular catheter |
| Epidural hematoma is usually caused by injury to what structure? | Middle meningeal a when temporal bone is fractured |
| Classic presentation for epidural hematoma? | Brief LOC followed by a lucid interval--> coma (transtentorial herniation). May also see ipsilateral blown pupil. |
| Diagnosis for epidural hematoma? | Convex mass on CT |
| Tx for epidural hematoma? | Rapid surgical decompression |
| Cause of subdural hematoma? | Venous bleeding after blunt head trauma (rupture of bridging vv) |
| Typical findings in subdural hematomas? | Decreased LOC, headache, cortical dysfunction |
| Diagnosis of subdural hematoma? | Cresent-shaped concave hematoma on head CT. |
| Tx for subdural hematoma? | Acute: surgical evacuation Chronic: may resolve on its own depending on size |
| Why should a CT scan of thorax be ordered in suspected myasthenia gravis? | To rule out thymoma |
| Which malignancy is associated with Lambert-Eaton Myasthenic syndrome? | Small cell lung cancer |
| Difference between myasthenia gravis and Lambert-Eaton syndrome? | In Lambert-Eaton, symptoms improved with repeated m stimulation. In myasthenia gravis, weakness is exacerbated by repeated m stimulation |
| Tx for myasthenia gravis? | Anticholinesterase drugs like pyridostigmine (symptomatic), thymectomy (may provide remission), corticosteroids (for poor response to AChE inhibitors), plasmapheresis, IgG (for acute exacerbations) |
| Indication for intubation in myasthenia crisis? | FVC of 15. Do NOT wait until pt is hypoxic-- they have a low threshold for intubation. |
| Inheritance of Duchenne's Muscular Dystrophy (DMD)? Mutation? | X-linked recessive. Mutation on gene that codes for dystrophin protein. |
| Is there an inflammatory response in DMD? | NO! Mm die in absence of dystrophin with no inflammation. |
| Diagnosis of DMD? | Elevated serum creatine phosphokinase and m biopsy (replacement of necrotic m tissue by fat and CT) |
| Tx for DMD? | None. Prednisone may slow progression of disease for ltd period of time. |
| AR inheritance of disease causing m cramping after exercise. Diagnosis? Cause? | McArdle's disease. Caused by deficiency of glycogen phosphorylase. |
| Which medications exacerbate the symptoms of myasthenia gravis? | Abx (aminoglycosides, tetracyclines), beta blockers, antiarrhythmics (quinidine, procainamide, and lidocaine) |
Created by:
sarah3148
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