EMG / NCV — Clinical Localization Laboratory
Electrodiagnostic Localization • Clinical Reasoning • Source-Bounded Evidence
Enter the electrophysiological findings of a study — which muscles were abnormal on needle EMG, which were normal, which were never sampled; which SNAPs and CMAPs were recorded and what they showed; whether the paraspinals were examined — and this laboratory works out which anatomical levels those findings support, which they contradict, and which cannot be judged from what was sampled. It reasons across root, muscle, peripheral nerve, trunk and cord, assigns one of three published confidence categories, and prints the source sentence behind every line of evidence together with where that sentence lives and whether it could be verified.
It names a level and a lesion type and stops there. It diagnoses no disease, computes no score, applies no temperature correction, and returns “indeterminate / insufficient evidence” rather than promoting the least poorly supported candidate to an answer.
Localization Comparator
level and lesion type, not a diagnosisqualitative confidence onlyno simulationEnter what a study actually found, and this laboratory works out which anatomical levels those findings support — and which they cannot. Every line of evidence carries the source sentence behind it, where that sentence lives, and whether anyone in this project has been able to read it. This laboratory localizes a LEVEL and names a LESION TYPE. It does not diagnose a disease. REV3 Module 12 is explicit: an electrodiagnostic study describes a physiological pattern, and “That description is not itself a disease diagnosis.”
Confidence here is one of three qualitative categories with published definitions. No number, percentage, probability, weight or ranking value is computed anywhere in this laboratory, and no arithmetic is performed on evidence.
A muscle that was not sampled and a study that was not done are reported as such and are never counted as normal. Incomplete sampling is one of the reasons REV3 gives for a pattern falling short of high confidence, so it limits the conclusion rather than disappearing from it.
The comparator reasons inside ONE innervation source at a time and labels its conclusion with that source. The four datasets disagree, differ in granularity and differ in whether they could be verified in this project, so they are never merged into a consensus table. Changing the source can change the localization; that is the literature, not a fault.
Where the findings do not support a level, the laboratory returns “Indeterminate / insufficient evidence” and names what is missing. It never promotes the least bad candidate to a conclusion.
Scope and innervation source
Selected source: Read directly from this source in the project library. 5 muscle(s) of this limb are named by it.
Needle EMG — muscles this source names
Every muscle starts as Not sampled, and not sampled is never read as normal.
Nerve conduction studies
Six upper-limb studies carry a pathway-relevance statement from MISRA P4-B13-T1. Each says the study “provides information relevant to” a plexus element — it does NOT say the nerve arises from those roots. The comparator uses only the weaker claim, and the source's own closing qualification applies throughout: definitive anatomical localization strictly requires correlation with other electrodiagnostic studies, needle EMG sampling and clinical findings.
Technical validity and clinical context
Days since injury is a shared variable, currently 0. It selects which published day band applies below and changes nothing else.
Localization statement
indeterminateNo confidence category — indeterminateNothing has been entered yet. Every muscle is unsampled and every study undone, so there is nothing to reason from — which is reported as such rather than as a normal study.
Indeterminate / insufficient evidence. No anatomical level is supported by the findings entered, reasoning inside REV3 Module 8 — Needle Muscle Atlas. This is not a negative study: what is missing is listed below.
Confidence: No confidence category — indeterminate
Clause matched: “no level is supported”
No anatomical level is supported by the findings entered. The laboratory returns Indeterminate / insufficient evidence rather than promoting the least poorly supported candidate. A normal routine study does not exclude pathology: the source records that isolated small-fiber pathology may produce entirely normal routine electrodiagnostic findings.
- [technically limited] No limb temperature has been stated for this study. Nothing is corrected, nothing is scaled and no threshold is checked — a missing temperature is reported as missing and is never treated as an adequate one. REV3 places temperature third in its diagnostic hierarchy and second in its localization framework, so an unstated temperature is itself a limit on technical validity.
- [technically limited] Whether the findings were reproduced has not been stated, so technical validity is not established.
- [a confounder that cannot be excluded] Clinical concordance has not been stated. High confidence requires concordant clinical findings.
- [a confounder that cannot be excluded] No pathophysiology has been stated. High confidence requires a plausible pathophysiology, and the source is explicit that the physiological description is not itself a disease diagnosis.
Recorded, but attached to no level
No anatomical level was triggered, so this evidence has nowhere to attach. It is kept rather than discarded.
• No sensory nerve conduction study was recorded for this limb. The contrast between a preserved and a reduced SNAP is the most useful single discriminator between a preganglionic and a postganglionic level, and it is unavailable.
Trunk and cord candidates always come from Daube Table 47-16, whichever root source is selected. It is the only registered dataset with a trunk or cord dimension, and it was verified in this project. This is not a merge: each candidate's evidence cites its own source, and a root candidate never borrows a cell from Table 47-16.
Time since injury — which published band applies
Day 0 post-injury: Table 23-10 Compound Action Potential Amplitude after Peripheral Nerve Injury — “0-5 Days”; Table 23-11 Findings on Needle Examination after Peripheral Nerve Injury — “0-15 Days”.
Table 23-10 Compound Action Potential Amplitude after Peripheral Nerve Injury
Day 0 falls inside the printed range “0-5 Days”. The range is read as inclusive of day 5, which is what the printed text says.
Conduction block — proximal stimulation: Low
Conduction block — distal stimulation: Normal
Axonal disruption — proximal stimulation: Low
Axonal disruption — distal stimulation: Normal
Table 23-11 Findings on Needle Examination after Peripheral Nerve Injury
Day 0 falls inside the printed range “0-15 Days”.
Conduction block — Fibrillation potentials: None
Axonal disruption — Fibrillation potentials: None
AT THIS DAY COUNT A NORMAL DISTAL AMPLITUDE EXCLUDES NOTHING. Table 23-10 prints “Normal” for axonal disruption on distal stimulation in the 0-5 day column, the same cell it prints for conduction block. The source states it in words: “axons distal to an acute lesion may continue to function normally for as long as 5 days”.
AT THIS DAY COUNT ABSENT FIBRILLATIONS EXCLUDE NOTHING. Table 23-11 prints “None” for axonal disruption in the 0-15 day column. The source states that “Fibrillation potentials and motor unit potential changes begin after two weeks with axonal disruption.”
DAY 0 IS THE SHARED DEFAULT OF THE STATE STORE, NOT NECESSARILY A MEASUREMENT. If no interval since injury has actually been established, the banding below should be read as showing the earliest published band rather than as a statement about this study.
Supplied numerical ranges — location unestablished, used for nothing
The supplying evidence inventory attributes these figures to Daube Table 47-1 at page 804. That table was read in this project: it is categorical, like Tables 23-10 and 23-11, and contains no percentage and no day range. The figures are shown here so the difference between a published stage and an unlocated number is visible, and nothing in this laboratory computes with them.
“Distal motor CMAP amplitude declines by ~50% at days 3-5.”
Claimed location: Daube Table 47-1, page 804 (inventory also gives “PDF p. 253”). Tables 47-1/47-2 are at printed page 804, PDF page 833 — the inventory's PDF page is wrong. The table is categorical and contains no percentage. Tables 23-10 and 23-11 do not contain it either. Where this figure comes from is unestablished.
“Sensory SNAP amplitude declines by ~50% at day 7 and reaches its nadir at days 9-11.”
Claimed location: Daube Table 47-1, page 804. Not present in Table 47-1, 23-10 or 23-11, all of which were read here. Unestablished.
“Fibrillations appear at 7-10 days in paraspinal/proximal muscles and at 14-21 days in distal limb muscles.”
Claimed location: Daube Table 47-1, page 804. Not present in Table 47-1, 23-10 or 23-11. The verified material says only that fibrillations are None in the 0-15 day band, Present after it, and that they “begin after two weeks”. The proximal-versus-distal gradient is not in the verified material at all. Unestablished.
One further claim was checked and found absent, not merely unverified. REV3 is present in this project and was searched in full. “Wallerian”, “decay” and “step-function” occur ZERO times in its 99,283-character extraction. The sentence is not in REV3. Kimura page 100 could not be checked because no Kimura volume is present. Chaudhry & Cornblath (1992) is not in the project. NO CONTINUOUS DECAY MODEL IS BUILT. This was the only statement that would have authorised turning the categorical day bands into a function of time, and it does not exist in the document it was attributed to.
Only the fibrillation-potential rows of Table 23-11 were extracted and verified. The source table carries further rows that were not read and are therefore not registered; these two are not presented as the complete table.
Both tables print a third column headed “Recovery”. That is a clinical phase, not an elapsed-day range, so no number of days selects it and this laboratory never infers it from time alone. Its cells are shown for completeness and are never presented as applying at a given day.
No proximal-versus-distal onset gradient is modelled. The verified material does not distinguish them, and the supplied claim that does is unlocated.
The bands describe TWO injury categories — conduction block and axonal disruption — which are the tables' own row labels. They are not a disease list and not a severity scale.
Temperature — a reference layer, applied to nothing
No temperature stated for this study. No limb temperature has been stated for this study. Nothing is corrected, nothing is scaled and no threshold is checked — a missing temperature is reported as missing and is never treated as an adequate one. REV3 places temperature third in its diagnostic hierarchy and second in its localization framework, so an unstated temperature is itself a limit on technical validity.
Published per-degree coefficients — displayed, attributed, applied to nothing
The specification’s own prohibition: “Per-degree coefficients quoted in textbooks (for example, changes of the order of 1.8 microvolts and 0.3 ms per degree Celsius) are source-specific illustrative figures derived from particular nerves, techniques and populations, and must not be applied as universal conversion factors.”
Six published figures from four sources, which disagree with each other. REV3 explains why — each was derived from particular nerves, techniques and populations — and forbids treating any of them as a universal conversion factor. None is applied to any value in this laboratory; `appliedTo` is typed as the literal “NOTHING” so that no code path can change that.
Sensory amplitude and latency, per degree Celsius: “Per-degree coefficients quoted in textbooks (for example, changes of the order of 1.8 microvolts and 0.3 ms per degree Celsius) are source-specific illustrative figures derived from particular nerves, techniques and populations, and must not be applied as universal conversion factors.”
REV3 Module 3 — Temperature, Age, and Height (paragraph 50). Applied to: NOTHING.
Distal latency: “Distal latencies prolong by +0.3 ms per °C cooling for median and ulnar nerves.”
Kimura 3e, Chapter 5, pages 109-110 (as supplied) — as reported in the cited source. Applied to: NOTHING.
Conduction velocity: “Conduction velocity slows by -1.8 to -2.0 m/s per °C drop below 32°C (or increases linearly by 2.4 m/s / ~5% per °C between 29°C and 38°C).”
Kimura 3e, Chapter 5, pages 109-110 (as supplied) — as reported in the cited source. Applied to: NOTHING.
Conduction velocity, empirical adjustment: “Alternatively, adding 5% to calculated conduction velocity for each degree below 32°C serves as an empirical adjustment.”
Kimura 3e, Chapter 5, pages 109-110 (as supplied) — as reported in the cited source. Applied to: NOTHING.
Latency and conduction velocity: “For each degree celsius fall in temperature, the latency increases by 0.3 ms... velocity increases by 5% per degree from 29-38ºC. The laboratory temperature, therefore, should be maintained between 21-23ºC. If skin temperature is below 34ºC, the limb should be warmed...”
Misra — Clinical Neurophysiology, Chapter 3, page 32 (as supplied) — as reported in the cited source. Applied to: NOTHING.
Sensory onset latency, peak latency and SNAP amplitude: “Cooling hand skin from 34°C to 26°C prolongs distal onset latency by 0.06 ms/°C, peak latency by 0.1 ms/°C, and increases SNAP amplitude by 1.8 µV/°C.”
Lee 1993, cited in Misra — Clinical Neurophysiology, Chapter 3, page 32 (as supplied) — as reported in the cited source. Applied to: NOTHING.
Where the innervation sources disagree
Computed across labels that name the SAME muscle at the same granularity. A group label against a component label is a difference in granularity and is not counted here, and a source whose root list qualifies the nerve rather than the muscle is not compared at all. Nothing below is reconciled. The label alias table is a naming decision made in this project, not a source. It asserts nothing about innervation: which roots, nerves, trunks or cords reach a muscle is always read from a registered dataset. The table only records which printed labels refer to the same muscle, and every entry carries the relation it claims.
No comparable disagreement in this limb. That is not agreement between the sources — for the upper limb it is because only one source states muscle-to-root relations at all.
Trunk root composition, kept separate on purpose: Upper trunk (C5-6); Middle trunk (C6-7-8); Lower trunk (C8-T1). These are column headers of Table 47-16. They are never joined to its muscle cells, because the table assigns muscles to trunks and states trunk composition as two separate pieces of information.
Provenance — what this conclusion rests on
REV3 Module 8 — Needle Muscle Atlas: eight rows of Muscle / Nerve & Roots / Insertion Landmark / Activation Maneuver / Clinical Relevance & Pitfalls
Transcribed from the source held in the project library
REV3 Modules 12-14 and the Module 7 sural territory note — the radiculopathy and plexopathy diagnostic patterns, the DRG principle with its stated weakeners, paraspinal sparing in both directions, and the prohibition on reading a pattern as a diagnosis
Transcribed from the source held in the project library
Daube & Rubin, Clinical Neurophysiology 3e, Chapter 47, Table 47-16 — Muscle Innervation According to Trunk, Cord, and Nerve (muscle to trunk and nerve only; the cord dimension could not be recovered)
Transcribed from the source held in the project library
Daube & Rubin, Clinical Neurophysiology 3e, Chapter 23, page 356, Tables 23-10 and 23-11 — compound action potential amplitude and needle findings after peripheral nerve injury, by injury category and day band, with the page's body text
Transcribed from the source held in the project library
NCS temperature — source-derived reference layer: the REV3 prohibition on universal per-degree conversion factors, seven published standardisation thresholds from four sources, six published per-degree coefficients and three confounding statements, each attributed and applied to nothing
Transcribed from the source held in the project library
Scope limits that apply to every statement here
• This is a localization statement, not a diagnosis. The source states that an electrodiagnostic study describes a physiological pattern and that “That description is not itself a disease diagnosis.”
• No number appears in this conclusion. Confidence is one of three qualitative categories with published definitions, and nothing in this laboratory computes a score, a percentage, a probability or a weight.
• Nothing that was not examined has been imputed. Muscles that were not sampled and studies that were not done are listed as such and are never counted as normal.
• Sensory evidence here discriminates lesion TYPE — preganglionic against postganglionic — and not an individual segment. No dermatome-to-root source is registered in this project.
• No temperature coefficient was applied to any value. The specification states that per-degree coefficients “must not be applied as universal conversion factors”.
• One innervation source was used and the others were not consulted. The datasets disagree and are never merged; changing the source may change this conclusion.
What each control does, and what this laboratory has no control for
Limb LOCALIZATION_REASONING_ONLY
Chooses which muscles, studies and spinal levels are in scope. Upper and lower limb draw on different datasets, and only the upper limb has a registered plexus map.
Watch for: Switching to the lower limb removes trunk and cord candidates entirely and says why: Table 47-16 is upper-limb only and no lumbosacral plexus map is registered anywhere in this project.
Innervation source LOCALIZATION_REASONING_ONLY
Which dataset the root-level reasoning runs inside. One at a time, never merged, and the conclusion is labelled with it and with whether it could be verified in this project.
Watch for: THE SAME FINDINGS CAN LOCALIZE DIFFERENTLY UNDER DIFFERENT SOURCES. That is the single most instructive thing this laboratory does. Misra prints no nerve column, so the multi-nerve heuristic cannot even be tested against it; Daube assigns no roots at all, so selecting it removes root candidates and leaves trunk and cord.
Needle EMG by muscle LOCALIZATION_REASONING_ONLY
The most informative single component of the study for root-level localization, in the source's own words. Each muscle is normal, abnormal in one of the published ways, or not sampled — and not sampled is the default.
Watch for: Marking a second muscle abnormal can change the conclusion more than marking the first, because the myotomal heuristic turns on two muscles sharing a root through DIFFERENT nerves. One abnormal muscle never localizes to one root: most muscles receive innervation from more than one root.
Paraspinal needle examination LOCALIZATION_REASONING_ONLY
The structural discriminator between a root and a plexus level: the posterior primary rami leave the spinal nerve before the plexus is formed.
Watch for: NEITHER ANSWER IS DECISIVE AND THE LABORATORY REFUSES TO TREAT EITHER AS SUCH. Normal paraspinals do not exclude a radiculopathy, and abnormal paraspinals do not exclude a coexisting plexus lesion. Both appear as not-assessable items carrying the source's own reason, never as evidence against a level.
Sensory nerve conduction (SNAP) LOCALIZATION_REASONING_ONLY
The DRG principle. A preserved SNAP supports a lesion proximal to the dorsal root ganglion; a reduced or absent one supports a postganglionic lesion.
Watch for: This evidence discriminates LESION TYPE, not an individual segment — the source's statement is about a dermatome and no dermatome-to-root source is registered here. The sural response carries its own prohibition: a preserved sural may not support an L5 localization.
Motor nerve conduction (CMAP) LOCALIZATION_REASONING_ONLY
Amplitude and the one focal pattern the sources name. In radiculopathy, amplitudes may fall where axonal loss is severe while distal latencies and velocities typically stay normal.
Watch for: A focal slowing or block supports a lesion AT THE SEGMENT CROSSED, which is a nerve-level finding. The numerical thresholds in the source's statements are source-specific criteria, not universal cutoffs, and none is applied here.
Soleus H reflex LOCALIZATION_REASONING_ONLY
May provide supportive information where S1 root or proximal tibial pathway dysfunction is suspected.
Watch for: An absent H reflex adds support at S1 and can never decide it. The source states it is not anatomically specific and is not a stand-alone diagnostic test.
Findings reproduced LOCALIZATION_REASONING_ONLY
Repetition and reproduction are step 10 of the Module 1 diagnostic hierarchy, and technical validity precedes physiological interpretation.
Watch for: Leaving this unstated holds the conclusion at limited confidence however clean the pattern is, because technical validity has not been established.
Limb temperature stated for this study LOCALIZATION_REASONING_ONLY
The shared store always holds a temperature, so this says whether one was actually stated. Until it is, the temperature layer evaluates nothing at all.
Watch for: NOTHING IS EVER CORRECTED. Stating a temperature checks it against the published thresholds and nothing else. The published per-degree coefficients are displayed with their attribution and applied to no value, because the specification forbids treating them as universal conversion factors.
Pathophysiology stated LOCALIZATION_REASONING_ONLY
Axonal, demyelinating or mixed — the only vocabulary the source permits, and it is a learner statement rather than something this laboratory derives.
Watch for: High confidence requires a plausible pathophysiology to have been stated. Stating one is not a diagnosis: the source is explicit that the physiological description is not itself a disease diagnosis.
Clinical concordance LOCALIZATION_REASONING_ONLY
Step 8 of the localization framework, and a learner judgement rather than a computation.
Watch for: Discordant findings make the study internally inconsistent and hold it at limited confidence. Unstated concordance holds it at moderate.
Confounders declared unexcludable LOCALIZATION_REASONING_ONLY
Six confounders the sources themselves name. There is no free-text option, because a confounder with no source behind it could not be cited in the final statement.
Watch for: Declaring one caps the conclusion at moderate confidence, which is exactly what the published definition says: a consistent pattern limited by a confounder that cannot be excluded.
Disease or diagnosis — deliberately absent
Deliberately not built. The laboratory names a LEVEL and a LESION TYPE. REV3 Module 12 states that an electrodiagnostic study describes a physiological pattern and that “That description is not itself a disease diagnosis”, with the diagnosis following from history, examination, time course, and laboratory and imaging findings that this laboratory does not hold.
Numerical confidence, probability or weighting — deliberately absent
Deliberately not built and may not be. The three confidence categories are qualitative words with published definitions. No number, percentage, probability, weight or ranking value exists anywhere in this laboratory, and no arithmetic is performed on evidence.
Severity or prognosis — deliberately absent
Deliberately not built. No registered source in this project grades severity or states a prognosis from a finding pattern, and the Wallerian tables describe injury category against time rather than severity.
Apply temperature correction — deliberately absent
FORBIDDEN BY THE SOURCE, not merely omitted. REV3 states that per-degree coefficients “must not be applied as universal conversion factors”. The coefficients are shown with their attribution; the field that would carry their application is typed as the literal “NOTHING”.
Dermatomal sensory loss — deliberately absent
Deliberately not built. No registered source in this project supplies a dermatome-to-root map, so a dermatome control could only appear to localize. Sensory reasoning runs on named nerves and the territories the sources themselves name.
Combined / consensus innervation table — deliberately absent
Deliberately not built. The four innervation datasets disagree, differ in granularity and differ in verification standing. A merged table would hide all three, and REV3 Module 10 states that values from different sources “are never merged into a composite dataset”.