2023 - 2024 SSEPs and VEPs - CNIM Complete Questions & Answers (Solved) 100% Correct
- Somatosensory Evoked Potentials (SSEPs)
Answer:
-Assesses somatosensory system functioning.-Usually uses bipolar trancutaneous electrical electrical stimulation of the medial nerve (MN) or the posterior tibial nerve (PTN), then recording from the scalp.
- Non-Pathologic Factors that Affect SSEPs
Answer:
-Motor/Sensory Threshold -Adequacy of peripheral nerve response -Equalizing peripheral nerve response -Filter effects -Limb temperature and length -Anesthetic
- Motor/Sensory Threshold
Answer: -If threshold is too low, it may be difficult to elicit a wave in absence of muscle relaxant.
- Adequacy of Peripheral Nerve Response
Answer:
-Measured for adequacy by measuring potential at Erb's Point and the Popliteal Fossa.-Nerves are considered saturated when waveform amplitude is unaffected by continuing increase of stimulation.
- Filter Effects
Answer:
-Phase lead (low frequency filter) and phase lag (high frequency filter) effects are present in SSEPs.-Lower the number, later the latency.-Notch filter should only be used in extreme cases of 60 Hz interference, as it affects waveform latency and amplitude.-BAEPs also affected.
- Limb Temperature and Length
Answer:
-Waveform latency and amplitude affected by temperature.-Increased latency with increased limb length.-Temperature affects conduction velocity of neuron.
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- Anesthetic Factors
Answer:
-Affect SSEP recordings and BAEP recordings.-SSEPs more affected because they are recorded from sensory cortex and not the brainstem.Sensory cortex more affected by anesthetics.-Inhalation anesthetics affect cortically generated waveforms by depressing activity in the cortex.
- Pathologic Factors
Answer:
-May or may not be problems with the nerves themselves.-Some factors include issues with circulation and edema in area of stimulating electrodes.-Friedreich's Ataxia -Multiple Sclerosis (MS) -Huntington's Chorea
- Friedreich's Ataxia
Answer:
-Heritable disorder -Gait disturbance (ataxia), speech problems, and heart disease.-Results from degeneration of sensory nerve tissue.-Primarily affects spinal cord and peripheral nerves.-Sclerosis and degeneration of dorsal root ganglion, spinocerebellar tracts, lateral corticospinal tracts, and dorsal column.-Hearing and vision can be affected.-SSEPs become abnormal as symptoms progress.
- Multiple Sclerosis (MS)
Answer:
-Autoimmune disease in which immune system at- taches the CNS, leading to demyelination of axons.-Increase SSEP absolute and interpeak latencies.
- Huntington's Chorea
Answer:
-Onset of uncoordinated, jerky body movements and decline in some mental abilities.-Affects cortical response amplitude and latency in SSEPs.
- Peripheral Neuropathy
Answer:
-Damage to the peripheral nerves from diseases, tox- ins, vitamin deficiencies, and physical trauma.-Can affect SSEPs.
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