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แพทย์หญิง กาญจนา พิทกั ษ์ วฒ ั นานนท์ อายุรแพทย์ผ้ เู ชี่ยวชาญระบบประสาท แพทย์ประจาศูนย์สมอง โรงพยาบาลสมิติเวชศรี ราชา The activity recorded in the EEG originates mainly from the superficial layers of the cerebral cortex. Current is believed to flow between cortical cell dendrites and cell bodies As a result of the synchronous activation of axodendritic synapses on many neurons , summed electrical currents flow through the extracellular space , creating the waves recorded as the EEG Clinical applications Seizure Sleep disorder Encephalopathy Recording in response to a variety of sensory stimuli SSEP VEP AERP BERP Measured in terms of latency and amplitude The most common stimulus involves alternating light and dark checkerboard squares P100 or P1 latency refers to a positive deflection recorded over the occiput , normally occurring around 100 millisecs Clinical applications • • • • • • • Optic neuritis ( highly sensitive ) Anterior ischemic optic neuropathy Sarcoidosis Leber’s hereditary optic neuropathy Papilledema Chiasmal tumors ( eg.,pituitary adenoma ) Psychogenic visual loss ?? Clinical applications • brain death • coma from ?? • cortical dysfunction • brainstem dysfunction • acoustic neuromas ?? • early detection subclinical MS From peripheral nerve to sensory cortex Motor nerve & sensory nerve amplitude latency conduction velocity Afferently CN V ( sensory ) Efferently CN VII ( motor ) Insertion activity Spontaneous activity Muscle contraction activity Neuromuscular transmission Peripheral neuropathy Plexopathy Nerve root Spinal cord lesion For diagnosis and treatment Normal / LEMS MG MRI involves first alingning the protons within human tissues in a strong magnetic field The alinment is briefly interrupted via generation of a radiofrequency pulse. The relaxation characteristics of protons in various tissues are then recorded as they recover magnetization. ◦ ◦ ◦ ◦ T1 : spin-lattice relaxation T2 : spin-spin relaxation TR : repetition time TE : echo time Short TR Short TE Best displays anatomy Bright Dark Fat , flowing blood , White matter , Gray matter , CSF , Bone , Air , Calcium , Hemosiderin , Flow void , Infarct Long TR Long TE Best highlights pathology Bright Dark CSF , Edema , Neoplasms , Abcess , Demyelination , Infarct , Gray matter , White matter , Bone , Air , Calcium , Hemosiderin , Flow void , Fat An image sensitive to local changes in the concentration of deoxyhemoglobin. MRI can provide maps that show regions of increased neural activity within the brain. ◦ ◦ ◦ ◦ Motor activity ( eg., tapping of fingers ) Sensory activity ( eg., stimulation part of body surface ) Cognitive activity ( eg., calculation , reading , recalling ) Affective activity ( eg., responding mentally to a fearful stimulus ) SPECT ( Single photon emission computed tomography ) Studies the uptake of gamma-releasing radionucleotides ( eg., hexamethylpropyleneamineoxime : HMPAO ) as a measure of blood flow PET ( Positron emission tomography ) A functional imaging study that correlates activity to glucose uptake and metabolism by measuring ( most commonly ) 18F-deoxy-glucose , a positron-emitting nucleotide Clinical applications 1. 2. 3. 4. Epilepsy : SPECT increase in ictal period Neoplasm : high rate of metabolism Dementia : hypometabolism Brain death