This document provides guidelines for performing and interpreting somatosensory evoked potentials (SSEPs), which assess sensory nerve conduction in the upper and lower extremities. It describes stimulation and recording procedures, including electrode placement and montages. For upper extremity SSEPs following median nerve stimulation, it identifies the key components N9, N13, P14, N18, and N20 and provides criteria for abnormal findings such as absent waves or prolonged interpeak latencies. For lower extremity SSEPs following posterior tibial nerve stimulation, it identifies the components LP, P31, N34, and P37 and also provides criteria for abnormal findings.
Basic MEP techniques and understanding for Intraoperative neuromonitoring of the motors tracts during Brain and Spinal surgeries to prevent postoperative complications.
This presentation looks at intraoperative monitoring of auditory evoked potential, somato sensory evoked potential and motor evoked potential, procedure, pitfalls and utility.
Basic MEP techniques and understanding for Intraoperative neuromonitoring of the motors tracts during Brain and Spinal surgeries to prevent postoperative complications.
This presentation looks at intraoperative monitoring of auditory evoked potential, somato sensory evoked potential and motor evoked potential, procedure, pitfalls and utility.
Lower Extremity SSEP: Obligate peaks and recording montages following stimulation of the posterior tibial nerve. EP = Erb's. Obligate peaks and recording montages following stimulation of the posterior tibial nerve. T12 = 12th thoracic vertebra, CS = Cervical Spine, Fpz = center of frontal pole, CP = midpoint between ...
This presentation is an introduction to the principles of Nerve Conduction Study and is entirely sourced from the book by David C Preston and Barbara E Shapiro: Electromyography and Neuromuscular disorders, 3rd Edition
This presentation discusses the basic principles governing EEG Rhythm Generation, and discusses the various circuits that generate and maintain cerebral oscillations.
what is RNS and what the techniques to perform this test in the lab. Its significance in the evaluation and diagnosis of NMJ disorders like MG, LEMBS etc..
Lower Extremity SSEP: Obligate peaks and recording montages following stimulation of the posterior tibial nerve. EP = Erb's. Obligate peaks and recording montages following stimulation of the posterior tibial nerve. T12 = 12th thoracic vertebra, CS = Cervical Spine, Fpz = center of frontal pole, CP = midpoint between ...
This presentation is an introduction to the principles of Nerve Conduction Study and is entirely sourced from the book by David C Preston and Barbara E Shapiro: Electromyography and Neuromuscular disorders, 3rd Edition
This presentation discusses the basic principles governing EEG Rhythm Generation, and discusses the various circuits that generate and maintain cerebral oscillations.
what is RNS and what the techniques to perform this test in the lab. Its significance in the evaluation and diagnosis of NMJ disorders like MG, LEMBS etc..
The somatosensory system is the part of the sensory system concerned with the conscious perception of touch, pressure, pain, temperature, position, movement, and vibration, which arise from the muscles, joints, skin, and fascia.
The somatosensory system is a 3-neuron system that relays sensations detected in the periphery and conveys them via pathways through the spinal cord, brainstem, and thalamic relay nuclei to the sensory cortex in the parietal lobe
Impulses are carried from receptors via sensory afferents to the dorsal root ganglia, where the cell bodies of the first-order neurons are located.
Here the fibers split into 2 functional groups: a lateral group (or anterolateral system) and a medial group (or dorsal column-medial lemniscal system).
The lateral group carries mainly unmyelinated fibers that subserve pain and temperature sensations, whereas the medial group carries mainly myelinated fibers that convey proprioceptive impulses
Their axons then travel through the spinal cord either in an ipsilateral or a contralateral fashion. Note that second-order neuron cell bodies are located in different anatomical areas depending on the sensation they carry.
Broadly, the spinal cord contains the second-order neurons for the fibers carrying pain, touch, and temperature sensations.
The lateral group of fibers enters the spinal cord, then ascend to terminate on the substantia gelatinosa and the nucleus proprius, where the second-order neurons are housed
Fibers then ascend via the brainstem to the thalamus in the spinothalamic tracts (or STT).
The medulla contains the second-order neurons for fibers carrying touch, position, and vibratory sensations. The fibers are then either conveyed to the thalamus (where the third-order neurons are located)
The medial group also sends its fibers into the posterior spinal cord; however, upon reaching it, most fibers ascend to the dorsal column nuclei in the medulla and synapse there
These tracts synapse on a second-order neuron in the nucleus gracilis and cuneatus, which are located in the medulla.
Their axons then decussate form a bundle known as the medial lemniscus.
Fibers of the posterior columns and medial lemniscus are concerned primarily with position sense and fine discriminative touch
These fibers travel to the midbrain on their way to the thalamus. Once in the thalamus, they synapse on third-order neurons in the ventral posterior lateral (VPL) nucleus.
The third-order neurons then project to the primary somatosensory cortex, which is located in the postcentral gyrus (also known as Brodmann areas 1, 2, and 3) of the parietal lobe
Primary somatosensory cortex subserves general and proprioceptive sensations and serves to integrate sensory information
Somesthetic cortex is organized in a sensory homunculus
Body areas particularly important to the sensory system (for example the face, lips, and hand) are given larger representation than other areas
Sensory receptorsperipheral nerve dorsal
Anomalous Innervations in (EMG/NCS) by MurtazaMurtaza Syed
Anomalous Innervation.
These are the sort of normal variants which can be found in any normal subject or can concomitantly be found or superimposed in pathological cases. Identifying these anomalies helps out interpreting and making correct diagnosis and to avoid any misinterpretation.
Late response are the most helpful findings in some of the diseases affecting the peripheral nerves, (e.g GBS, Radiculopathies, ). How to assess these responses while performing Nerve Conduction Studies, is the most technical and theoretical consideration.... Here we go with the same things in the stated slides
EEG variants, are always to be recognized while interpreting the EEG one must be aware of these. Major and most common EEG is variants are discussed in the stated presentation.
Syed Irshad Murtaza.
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Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
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Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
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Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
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4. Stimulation
• Stimulation: Transcutaneously using electrodes placed on the
skin over the selected nerve.
• Contact impedance: 5 KOhms or less
• Ground electrode: on the stimulated limb to reduce stimulus
artifact.
• Monophasic rectangular pulses are delivered (constant
voltage or a constant current stimulator). Typical stimulus
parameters ….pulse width of 100-300 usec and stimulation
rate ….3-5 Hz.
• Stimulus intensity….. adequate to produce a consistent but
adequately tolerated muscle twitch is sufficient for standard
clinical testing.
5. Recording
• Standard EEG disk electrodes.
• Contact impedance: < 5 KOhms.
• Conductive paste: electrodes applied with collodion are more reliable than those
applied with EEG paste.
• System band-pass: approximately 30-3,000 Hz (—6 dB/octave).
(Use of a wider passband, extending down to 1 Hz long
duration signals , adds additional low-frequency noise …
requires averaging of a greater number of responses and
may substantially prolong recording time).
• Analysis time: double the last peak to be recorded of interest ( for median nerve SSEPs
and 60 ms for posterior tibial nerve SSEPs, 75- 150 msecs).
It is occasionally necessary to extend the analysis time in order to distinguish
between a very
delayed and absent response.
• Averaging: depends on the noise present and the voltage of the signal to be recorded;
(several 100 to several 1000 responses, ensure that the recorded waveforms
represent stimulus-locked signals and not noise).
For low noise recording, two replications are usually adequate.
For higher noise recordings, more than two replications are often required.
6. • Noise: usually from muscle activity and patient movement.
Current restrictions on the administration of sedatives
…..consider other techniques for obtaining patient relaxation.
(Because the peak latencies of N20 and P37 cortical responses to
median and posterior tibial nerve stimulation can be influenced
by the level of subject arousal, it is important that similar
conditions be employed for both normative data acquisition and
patient testing)
7. Designation of Electrode Locations
A minimum of four channels are required to record SSEPs. Use of averagers with less
than four channels is discouraged.
• Cc and Ci ---- contralateral and ipsilateral to the stimulated limb.
• CPc and CPi ----halfway between C3 or C4 and P3 or P4.
• CPz ----midway between Cz and Pz.
• C2S and C5S ----electrode positions over the second and fifth cervical vertebra.
• Tl0S, T12S, and L2S ----electrodes over the corresponding thoracic and lumbar
vertebrae.
• EPi -----electrode over Erb‟s point, ipsilateral to the stimulated limb.
• AC ---an anterior cervical electrode position just above the thyroid cartilage in the
midline.
• LN ---- lateral neck electrode position at the midpoint of a line drawn between C55
and AC.
• IC ----to an electrode position on the iliac crest.
• Pfd and Pfp ----electrodes in the midline of the popliteal fossa, 2 cm and 5 cm
respectively above the popliteal crease.
• REF -----noncephalic reference.
9. Designation of Components
SSEPs following median nerve stimulation include the following obligate components.
• EP is the propagated volley passing under Erb‟s point.
• N13. is the stationary (nonpropagated) cervical potential recorded referentially
from the dorsal neck, probably reflecting mainly postsynaptic activity in the
cervical cord
• P14. is a subcortically generated far-field potential, recorded referentially from
scalp electrodes. It has a widespread scalp distribution and probably reflects
activity in the caudal medial lemniscus.
• N18. is a subcortically generated far-field potential, best recorded referentially
from scalp electrodes ipsilateral to the stimulated nerve, away from the
contralateral N20. It probably reflects postsynaptic activity from multiple generator
sources in brainstem and perhaps thalamus .
• N20. reflects activation of the primary cortical somatosensory receiving area, …is
recorded using a bipolar derivation to subtract the widespread far-field signals
(e.g., P14 and N18) from the superimposed primary cortical activity recorded
locally over the centro-parietal region contralateral to the stimulated median
nerve.
10. Stimulation
Median nerve stimulation at the wrist
Cathode is placed between the tendons of the PL and FCR,
approximately 2 cm proximal to the wrist crease, anode is
then placed 2—3 cm distal to the cathode, or on the
dorsum of the wrist.
A ground electrode (metal plate electrode, circumferential
band electrode, or “stick-on” electrocardiographic-type
electrode) is placed on the forearm.
Stimulation should produce a clearly visible muscle twitch
causing abduction of the thumb.
12. • Erb‟s point contralateral to the stimulated limb (Epc) is a recommended
noncephalic reference. More distant references, such as elbow, hand, knee, or
ankle (bony prominences may also be used).
13. Montage modifications and
extensions.
• C5S-Fpz derivation….. may be helpful in cases in which the amount of noise
present in the recording precludes noncephalic referential recording.
• Many laboratories record N20 using a CPc-Fz derivation. The latter derivation
results in a waveform that is a composite of the parietal N20 and the frontal
P22.
• A channel may be devoted to recording the frontal P22. Fc-CPi (i.e., F3 or F4
opposite the stimulated limb)—records the P22 in isolation ( in the same
manner as CPc-CPi records N20)
15. Analysis of results
• Identify EP, N13, P14, N18, and N20.
• Measure following peak latencies
EP; P14; N20;
Interpeak latencies
• EP to N20- conduction time between the brachial
plexus and the primary SC
• EP to P14-conduction time between the brachial
plexus and the lower brainstem; and
• P14 to N20- conduction time between the lower
brainstem and the cortex.
16. • Some laboratories also calculate
EP—N13… CT bw BP and CC
N13—N20…. cervical cord to cortex.
17. Criteria for abnormality.
Absence of any obligate waveforms.
Absent N-20….?
EP and N-20 present, absent N-13, P-14
Prolongation of the inter-peak latencies.
2.5 or 3 SD greater than the mean of an appropriate control
population is interpreted as abnormal and reflecting delayed
conduction between appropriate structures
• prolongation of the EP-P14 interpeak latency…delayed
conduction between the …and ….
• Prolongation of the P14-N20 interpeak latency….delayed
conduction between the ….and …..
18. • Because absolute latencies are directly
influenced by arm length and temperature,
they should not be used as a criterion for
abnormality.
• latency of the N20 cortical response varies slightly with
the level of arousal of the patient, normative data and
patient testing should ideally be performed with the
same conditions.
• In the absence of such controls, caution is recommended
in the interpretation of interside latency differences
20. Designation of Components
• LP.. is a stationary (nonpropagated) lumbar potential recorded
referentially over the dorsal lower thoracic and upper lumbar
spines, reflecting mainly postsynaptic activity in the lumbar
cord .
• N34.. is a subcortically generated far-field potential.
..recorded referentially from an Fpz electrode and is most
likely analogous to N18 following median nerve stimulation….
reflects postsynaptic activity from multiple generator in
brainstem and perhaps thalamus.
N34 is preceded by a small positivity, P31, most likely
analogous to P14 to median nerve stimulation
21. P37…reflects activation of the primary cortical somatosensory
receiving area…. recorded using bipolar derivations to subtract
other widespread far-field signals.
• There is considerable variability in the scalp topographic
distribution of the P37 response.
• It is usually maximal somewhere between midline and
centroparietal scalp locations ipsilateral to the stimulated leg.
• It is necessary to record from both midline and ipsilateral
scalp locations… before calling it as absent.
22. Stimulation
• Posterior tibial nerve stimulation at the ankle ….
recommended for standard testing …..evaluating the integrity
of central SS pathways sub-serving the lower extremity.
• Responses to posterior tibial nerve stimulation are subject to
less intersubject variability than those to common peroneal
nerve stimulation.
• With the patient in the supine position, the cathode-- midway
between the medial border of the Achilles tendon and the
posterior border of the medial malleolus. The anode-- 3 cm
distal to the cathode
23.
24. Recording
Minimal recommended montage.
• Optimal recording of lower extremity SSEPs, requires
documenting cortical and subcortical potentials, plus
recording the afferent volley at the popliteal fossa
(helpful in demonstrating adequacy of peripheral
stimulation),…. requires more than the four channels
available on most EP recording systems.
• If a four-channel montage is employed, it is important
that the neurophysiologist understands its limitations
and recognizes the occasional need to alter the
montage.
25. Montage 1, below, is recommended as a
minimal montage to record the obligate lower
extremity SSEPs
• Channel 4: CPi-Fpz
• Channel 3: CPz-Fpz
• Channel 2: Fpz-C5S
• Channel 1: T12S-REF
26. Details of Montage (Different Channels)
• Channel 1( T12S-REF) …… records the stationary LP…. widely distributed
over lower thoracic and upper lumbar spine and is subject to in-phase
cancellation in bipolar spinal derivations…. It should therefore be recorded
using a referential derivation . An electrode on the iliac crest is a
convenient reference. Some laboratories prefer to use a midthoracic
reference.
• Channel 2 (FPz-C5S)… records the subcortical far-field P31 and N34
potentials. In contrast to median SSEPs, C5S is relatively inactive following
posterior tibial stimulation and hence is a suitable reference for recording
subcortical far-field potentials P31 and N34. Other references (shoulder,
elbow) may be used, but these offer little advantage and tend to introduce
more noise.
27. Montage
Channels 3 and 4( CPz-FPz and CPI-FPz)
• register the P37 primary cortical response. Because of the variability in the
scalp topography of this response in normal individuals, P37 may
occasionally be present in only one of these channels.
• Use of two channels to record the P37 response is therefore necessary.
• In channels 3 and 4, Fpz is used as a reference allowing for subtraction of
underlying widespread far-field potentials, in a manner analogous to the
CPi electrode in channel 4 of montage 1 for median SSEPs (bipolar
derivation) .
• Some laboratories use an ear or mastoid electrode rather than an Fpz
electrode as an active reference for subtraction of underlying far-field
activity.
28. Montage modifications and extensions.
CPi-CPc derivation. …improves the signal-to-noise ratio by combining
approximately simultaneous phase opposite P37 and N37 signals. …
disadvantage that it produces a combination waveform representing a
composite of two somewhat dissimilar signals.
• If it is employed, the laboratory must have normative data specific to that
montage.
• Additional use of a midline bipolar (CPz-Fpz) derivation is still necessary.
Pfd- Pfp derivation--- to record the afferent volley at the popliteal fossa. …
useful in cases in which no response is recordable at and rostral to the lumbar
spine, …..to distinguish between an absent response and failure to stimulate
peripheral nerve…… at the expense of one of the scalp-scalp derivations
(channels 3 or 4).
• If this is done, however, it is necessary to repeat any study with an
ambiguous or absent P37 response using both CPz-Fpz and CPi-Fpz
derivations.
• Alternatively, other laboratories choose to omit the noise-susceptible Fpz-
C5S derivation from routine four-channel recordings in favor of including
the popliteal fossa channel.
29. Montage
Montage 2 is an example of an extended montage for posterior
tibial SSEP recording:
• Channel 8: CPc-Fpz
• Channel 7: CPz-Fpz
• Channel 6: CPi-Fpz
• Channel 5. Fpz-C5S
• Channel 4: T10-REF
• Channel 3: T12-REF
• Channel 2: L2-REF
• Channel 1: PFd-PFp
30. Analysis of results
Identify and measure following peak latencies
PF, LP, N34, and P37.
Measure following Interpeak latencies
• LP-N34 - conduction time between the lumbar spinal
cord and brain stem
• N34- P37 - conduction time between brainstem and the
cortex.
(Height correction is most important when the absolute latency of P37 is
evaluated, rather than the LP-P37 inter-peak latency. Caution is urged
when interpreting uncorrected inter-peak latencies for patients whose
height is at the extremes of the range of heights for which normative data
was collected.)
31. Criteria for abnormality
Absence of any of the obligate waveforms
In cases in which the signal-to-noise ratio of the recording is not
adequate to detect N34 were it present, failure to record it must not be
interpreted as an abnormality. Similar considerations apply for P31 and, in
occasional patients, LP.
Prolongation of the LP-P37 interpeak latency