Complete CNIM Study Guide with Practice Questions and Answers

When should you use SSEPs? - Answer- Use SSEP's for every case Where do you stimulate for UE SSEPs? - Answer- Ulnar Nerve - any surgery below the C4 level Median Nerve - any surgery above the C4 level Where do you stimulate for LE SSEPs? - Answer- Posterior Tibial Nerve at the ankle Pop Fossa - if severely diabetic or hypertensive Peroneal - if the patient is amputated below the knee N20 - Answer- N20 - Contralateral (to stimulation) post central gyrus. Near Field. MCA. CPi-CPc. Latency: 21.5 ms P23 - Answer- N18 - Answer- P14 - Answer- N13 - Answer- N13 - Post synaptic activity: cervical cord. Near Field Stationary Potential. EPc-CS5. PS artery. Latency: 13.9 ms Erbs Point (EP) - Answer- N11 - Answer- N9 - Answer- N9 - Ascending fibers/brachial plexus. Near Field Propagated Potential. Derivation: EPc-EPi. Latency: 11.8 ms P9 - Answer- N45 - Answer- P37 - Answer- P37 - Post central gyrus. Near Field. ACA. FZ-CPZ. CPc-CPi. Latency: 30-46 ms Pop Fossa (PF) - Answer- Stimulus intensity for SSEP - Answer- sufficient to cause a slight muscle twitch, higher used in atrophied limbs (higher intensity is painful and recruit motor >sensory responses). Stimulus rate in SSEP - Answer- 2-5 Hz for upper extremity stimulation and 1-2 Hz for lower extremity stimulation (rates greater than 10 Hz may cause an increase in latency and decrease in amplitude). Filter Setting in SSEP - Answer- 30-3000 Hz. (Not recommended to use the 60 Hz notch filter because SSEP in this range contains important physiologic information). Pulse width in SSEP - Answer- 100-300 µs Analysis time in SSEP - Answer- 40 ms for UE and 60 ms for LE. Amplifier sensitivity in SSEP - Answer- 10 µV for the spine and scalp potentials and 20 µV for peripheral potentials. Number averaged in SSEP (trials) - Answer- 500-2000 for reproducible wave forms (depends on noise). Electrode impedance - Answer- <5000 Ω SSEP Montage for UE recording - Answer- Channel 4: CPc-CPi > Cortical (N20) Channel 3: CPi-REF > Subcortical farfield (P14 [caudal medial lemniscus], N18 [thalamus]) Channel 2: C5S-REF > Stationary postsynaptic cervical (N13) Channel 1: EPi-REF > Past Erb's point (Ep) SSEP Montage for LE recording - Answer- Channel 4: CPi-Fpz > Cortical (P37) Channel 3: CPz-Fpz > Cortical (P37) Channel 2: EPz-C5S > Subcortical P31 and N34 (C5S is relatively inactive so good REF) Channel 1: T12-REF > Stationary lumbar potential (LP). System bandpass for SSEP - Answer- The recording bandpass is typically 30 - 1 kHz (-3db). The same considerations apply as for upper extremity SSEPs. When should you use spontaneous EMG (free run EMG, sEMG)? - Answer- In any surgery when there is possible nerve root compromise