The Functional-Neurology Workup

01What the instruments show

The Numbers Behind Each Instrument in the Battery

Eight findings on what these tests measure, and how far a reading must move to count.

02The premise

The Workup Measures How Precisely the Nervous System Runs the Athlete

A functional-neurology workup is a structured examination of how an athlete's nervous system senses, integrates and produces movement. It answers the question every serious competitor eventually asks. How well does my brain actually run my body.

The pre-participation exam answers a different question. It screens cardiovascular and musculoskeletal risk and clears the athlete for play, and The Pre-Participation Exam carries its yield figures and the cardiac screening debate. The functional workup begins where that clearance ends. It treats the brain, brainstem, cerebellum and spinal cord as the engine of performance, then measures the fidelity of each link.

This is collaborative work rather than a replacement for the team physician or the athletic trainer. One exam asks whether it is safe to compete. The other asks how precisely the athlete's nervous system performs, and where the margins for sharper coordination, faster reaction and better resilience actually live.

Four readouts, recorded in one room

Four readings organize the visit. Variability structure, taken from the beat-to-beat intervals of the heart. Coupling between slow and fast rhythms, read here as movement timing under a competing task. Reflex responsiveness. The time the system takes to return to baseline after a standardized demand.

None of that requires exotic equipment. A foam pad, a stopwatch, a reflex hammer, a near point ruler and a heart rate monitor cover most of it. What separates the workup from a list of screens is that the readings are taken together, in the same athlete, on the same afternoon, while nothing is wrong.

Recording several measures at once is where the concussion assessment literature landed. Across 1,458 college athletes, the arrangement that performed best combined symptom report, balance errors and a cognitive screen rather than any one of them alone Broglio 2019.

03The cranial and eye exam

Twelve Cranial Nerves Give the Fastest Read on the Brainstem

The cranial nerve exam tests all twelve cranial nerves and gives a fast, precise read on the brainstem, the most performance-dense real estate in the body. Eye movements driven by nerves three, four and six show how cleanly the athlete tracks, fixates and shifts gaze. That is the visual machinery behind every read of a ball or an opponent.

Pupillary response, facial symmetry, hearing, and the gag and palate reflexes map the rest of the brainstem in minutes. For an athlete this is not abstract. Smooth pursuit, saccadic accuracy and the vestibulo-ocular reflex are the literal hardware of sport vision. The full anatomy sits in the neurological exam.

The workup quantifies what the bedside exam grades by eye. One screen covers five domains: smooth pursuit, horizontal and vertical saccades, near point of convergence, horizontal vestibulo-ocular reflex and visual motion sensitivity. It was given to 64 patients about 5.5 days after a sport concussion and to 78 controls Mucha 2014. Sixty-one percent of patients reported symptom provocation on at least one item.

What an eye movement screen establishes, and what it does not

Two items carried most of the discrimination. The vestibulo-ocular reflex item returned an odds ratio of 3.89 and the visual motion sensitivity item 3.37 for membership in the concussed group Mucha 2014. A convergence distance of 5 centimeters or more raised the probability of correct identification by 38 percent, and any item scoring 2 or more on symptom provocation raised it by 50 percent.

Read that for what it is. The screen sorted two groups already known, and a model built from four of its readings reached an area under the curve of 0.89. That is a screening property rather than a diagnosis. The instrument records provoked symptoms and a measured distance. A clinician decides what they mean.

Saccade latency and pursuit gain as performance measures belong to Sport Vision and Eye Movements, and vestibulo-ocular reflex gain belongs to Vestibular Balance. The sideline protocol that pairs this exam with the Maddocks questions and the Glasgow Coma Scale, along with the Amsterdam 2023 consensus behind it, belongs to Concussion.

04Balance and coordination

Balance Scoring Reads the Cerebellum, and the Score Has to Beat Its Own Error

Balance and coordination testing measures the cerebellum, the structure that times and smooths every movement an athlete makes. The Balance Error Scoring System grades postural control across six conditions, three stances on firm ground and three on foam, counting errors as the athlete holds each position with eyes closed.

Removing vision forces the nervous system to rely on proprioception and the vestibular apparatus alone, exposing exactly how well the athlete integrates body sense without looking. Finger-to-nose, rapid alternating movements and heel-to-shin testing add a direct read of cerebellar coordination and timing. The cerebellum takes a heavy proprioceptive feed through the spinocerebellar tracts and uses it to correct movement before the error becomes visible, which is the basis of what looks like effortless control.

The error count carries a known margin. Total score reliability was 0.57 between scorers and 0.74 within a scorer, with individual stances running from 0.44 to 0.83 and 0.50 to 0.88 Finnoff 2009. The minimum detectable change was 9.4 points between scorers and 7.3 within one.

A better score can be the athlete learning the test

Repeating the test teaches it. Sixteen high school athletes tested on five occasions dropped from 12.88 errors at baseline to 10.94 on day 5 and 9.44 on day 7 Valovich 2003. A paired cognitive screen given the same days showed no practice effect at all. The single-leg stance on foam moved most.

So a falling error count has two possible authors, the nervous system or the practice. The workup answers by spacing retests, scoring the stances separately rather than trusting the total, and reading balance beside the other three readouts. Sway metrics and the complexity of the sway path belong to Vestibular Balance.

Coupling read at the tandem line

Adding a second task turns a walking test into a coupling measurement. Ten concussed athletes and seven controls walked a tandem line with and without a concurrent cognitive task, tested at five points out to two months Howell 2017. Dual-task completion took 16.4 seconds against 10.1 in controls through the first two weeks, and dual-task cadence ran 89.5 against 127.0 steps per minute.

Single-task walking separated the groups only at 72 hours. The competing task held the difference open for two weeks, and completion time tracked center of mass sway from 0.70 to 0.93 throughout. Timing under competition for attention is what the cerebellum supplies, and The Cerebellum and Timing carries that account.

05Reflexes and tone

Reflex Grading Is the Weakest Number in the Room and It Still Belongs There

Deep tendon reflexes, graded on the standard 0 to 4+ scale, give an instant readout of the spinal reflex arcs and the descending control riding on top of them. The loop closes faster than conscious thought.

Symmetry matters more than any single value. A brisk asymmetry or a difference in muscle tone between sides points to where the nervous system is driving one side harder than the other. That is a subtle imbalance, and it shapes movement long before it shows up as injury.

The grade itself travels badly between examiners. Physicians graded biceps, triceps, knee and ankle reflexes in two groups of 50 patients, using the Mayo scale in one group and the NINDS scale in the other Manschot 1998. Agreement between observers was never better than fair on either scale, with a highest kappa of 0.35. The authors suggest a verbal description in place of a codified number.

A reflex grade written by one examiner and read by another carries little. Left against right, taken by one examiner in one sitting, carries a great deal. The workup records the comparison rather than the grade.

Tone is the resting tension the nervous system holds

That resting tension sits in muscle, and it reports the athlete's central integrative state and autonomic readiness directly. The Neuron and the Central Integrative State gives the cellular account of how a neuron sums its inputs into one output state.

The autonomic reading in the room is heart rate variability, taken as RMSSD in milliseconds from a short seated recording. Heart Rate Variability owns that methodology and the training trials built on it.

A low reading is not the only signature of an overloaded athlete. Pooled training data show resting RMSSD rising both when a block improved performance and when it produced overreaching, and Tone and the Athlete's Edge carries that analysis. The model marks excess tone by a narrowed range and a blunted answer to a load, rather than by the direction of one number.

Mapping reflexes and tone together lets the workup read the wiring and the state of the system running through it. That is the difference between an athlete who is recovered and one who only looks it.

Better instruments for reflex responsiveness than a hammer

Reaction time and its variability, measured in milliseconds, belong to Reaction Time and Motor Control. Joint position sense error in degrees is recorded in Proprioception and Joint Position Sense. Cortical drive is quantified with transcranial magnetic stimulation in Cortical Drive and Force, where the N30 sensory peak has moved in both directions after cervical manipulation depending on the state it met.

Whether a reading has moved is a question about measurement error before it is a question about the athlete. The working answer is the typical error, the standard deviation of one person's repeated measurements Hopkins 2000. A precise estimate of it takes roughly 50 participants and at least three trials.

06The baseline

The Workup Produces a Baseline, and the Baseline Is What Makes Later Change Legible

The greatest value of a functional-neurology workup is the baseline it creates, a precise map of the athlete's nervous system taken when they are at their best. Reaction time in milliseconds, oculomotor accuracy, balance error scores, reflex symmetry and autonomic markers together form a signature unique to that athlete.

When something changes, after a head impact, a hard season or a plateau in form, the baseline is what makes the change legible. Without it, every later test is a guess against a population average instead of against the athlete's own peak. An athlete who has been mapped at peak is an athlete who can be read accurately when it counts.

Recency of the baseline is measurable. In the college cohort of 1,458 athletes, assessment combinations performed best when the difference score came from a baseline recorded in the same season Broglio 2019. Baselines from the year before produced weaker results, so retesting frequency became a finding in its own right.

The result that complicates the baseline argument

One large study pushed the other way. A total of 1,060 collegiate athletes completed baseline testing, gender-specific norms came from 673 of them with no concussion history, and 258 were later concussed and retested within 10 days Schmidt 2012.

Comparing each athlete to their own baseline found 2.6 times more impairments than comparing them to the normative mean on one simple reaction time measure. Comparing to the norm found 7.6 times more on mathematical processing. For postural control and symptom severity the two methods agreed, and the authors concluded that clinicians may consider normative data in place of individual baselines.

The Unified Model of Tone reads the pattern rather than the verdict. The two comparison methods disagreed on the fast, high-variance measures and agreed on the coarse ones. Where between-athlete spread is wide, the athlete's own history carries the information. Where a measure is slow and stable, a population mean does the same work.

Low reliability and a stable personal range are both true

Professional athletes make that point cleanly. Baseline testing was run on 179 professional male ice hockey players before two consecutive seasons Hanninen 2017. Test-retest reliability of the components was uniformly low, and most players still stayed inside their own performance range across a year.

The distribution of change scores is the usable product. Fewer than 10 percent of that healthy sample worsened by 3 or more symptom points from one preseason to the next. Fewer than 10 percent added 3 or more balance errors, and fewer than 10 percent added 4 or more seconds to tandem gait. A correlation coefficient never says that. A distribution of year-to-year change does.

This is why the functional workup belongs at the front of the season rather than only after something goes wrong, and why it is repeated rather than taken once.

07What the battery settles

What This Battery Establishes, and What It Does Not

No instrument in a functional-neurology workup diagnoses anything on its own, and the battery reads better than any part of it. That result decides how every number in the battery is used.

Reliable change bands were built on 38 healthy college football players tested twice, then applied to 132 athletes assessed before and after a concussion Register-Mihalik 2013. The full battery of symptom severity, neurocognitive throughput and posturography identified half of the injured and correctly cleared 96 percent of the uninjured. Sensitivity for each measure taken alone was lower still.

The investigators state the position plainly. A battery of several measures is more sensitive than any single one, and these measures do not adequately identify impairment in isolation. A workup built on one favorite test is weaker than the same clinician using four.

Reliability decides how much weight a reading carries. Across 118 healthy volunteers, three computerized assessment programs returned test-retest coefficients from 0.15 to 0.66 Broglio 2007. The authors recommend priority for the scores with the highest reliability, which is what a weighted battery does.

The standard this page holds itself to

Functional neurology as a field has been surveyed. A scoping review searched PubMed, PsycINFO and SPORTDiscus for work in the context of chiropractic manual therapy Meyer 2017. It found one textbook and 11 articles carrying an element of manual therapy, alongside five practitioner websites and four interviews. Diagnostic procedures, it reports, include both conventional and unusual tests, with interpretation specific to the approach.

Every instrument named here has published measurement properties, cited above, and every claim made about one is a claim about what it measures. A reading that belongs to the model rather than to the literature is named as the model's.

The exam is carried out by a board-certified chiropractic neurologist holding the DACNB and FACFN credentials, working alongside the team physician, the athletic trainer and the strength staff. The testing is drug free and compliant with anti-doping rules, which matters for a competitor under testing. Scope and documentation belong to Medical, Legal and Ethical Standards.

Three things the workup does not do are worth stating. It does not diagnose a concussion, which is a clinical decision described in Concussion. It does not substitute for imaging, and Imaging the Athlete covers when a picture is the right instrument. It does not forecast which athlete gets hurt.

Two neighboring instruments hold their own pages. Quantitative electroencephalography is set out in Brain-Based Performance Training, which states what a recording measures and what it leaves open. The visit where these readouts get taken together and scored against the athlete is The Performance Assessment.

08What we corrected

Four Claims Removed From This Page

This page previously carried a quotation attributed to Dr. Jason Dulberg that was not drawn from anything he said or wrote. It has been removed. Claims here are either sourced to the literature or named explicitly as the model's.

It credited the popularization of the pre-participation exam to a named clinician. That attribution could not be traced to a source and is gone. What the clearance exam catches, and at what rate, is carried in The Pre-Participation Exam.

It stated that a reflex corrects a joint in well under a tenth of a second. No source could be found for that figure, so it has been removed. What replaces it is the observer-agreement result above, where reflex grading scales never rose past fair agreement Manschot 1998.

It also said the workup lets the practice target work that sharpens motor control and resilience, and that an athlete in sympathetic overdrive shows depressed heart rate variability. The first is an efficacy claim and is removed. The second overstates a direction that training studies have found running both ways.

09The model's claim

Four Windows Onto One Organization, Opened in the Same Room

Two layers run through this page and they should not be confused. The established science is the reliability coefficients, the minimum detectable change and the practice effect. It is also the screening properties of the eye movement screen and the two comparison methods for a baseline. All of that belongs to the investigators who validated it.

The Unified Model of Tone decides what a battery is for. The model names four measures together. Heart rate variability and its internal structure. The phase coupling between slow and fast neural rhythms. The responsiveness of a reflex. The time a system takes to return to baseline after a demand.

Of those four the model says that each is a window onto the same underlying organization, and each can be recorded before the clinical outcome is known. That is the reason the readings are taken in one sitting rather than ordered one at a time, and the reason a weak instrument still earns a place beside three others.

The prediction this page makes

The protocol is ordinary equipment used in a particular order. RMSSD in milliseconds from a 5 minute seated recording. Dual-task tandem gait completion time in seconds. Near point of convergence distance in centimeters. Time for heart rate and balance error score to return to their pre-exertion values after a standardized submaximal exertion protocol.

Every reading is scored against that athlete's own preseason values, and a change counts only when it clears the typical error for that instrument Hopkins 2000. Balance is read by stance rather than by total score, and reflexes are read left against right by one examiner.

The model predicts those four move together within an athlete rather than drifting independently. An athlete whose convergence distance lengthens across a hard block should show it in dual-task tandem gait time and in a slower return to baseline, on the same afternoon, without any injury having occurred. This is a claim about how the athlete's readouts are organized rather than a claim about what treatment does.

The room already holds every instrument the test needs. One squad, four readings, four times a season. Combining instruments already beats any of them alone Register-Mihalik 2013, and the open question is whether it works because they are sampling one variable.

If RMSSD, dual-task tandem gait time, convergence distance and time to return to baseline after a standardized exertion protocol are shown to move together within athletes, the unification claim is confirmed.

10The tone reading

The Workup Reads Coupling, Input Quality and Time Course

Three signatures of tone show up in the instruments this exam already uses.

The rest of the library carries the same logic through its other foundations. Set point is the value each of these readings defends, which is why a map taken at peak is worth keeping. Gain is how hard the system answers a tap at the tendon or a turn of the head. Prediction is the feedforward model that makes a second task expensive to carry. Load is the standardized demand the recovery reading is timed against. Oscillation is the rhythm underneath a 5 minute RMSSD recording. Constraint is why a reading can sit too tight as easily as too loose. The full framework is set out in the Unified Model of Tone.

11Where this sits

How This Page Relates to the Rest of the Library

Seven places the instruments named here are carried in full, each with the claim that earns the link.

12Questions athletes ask

Questions Athletes Ask

13The sources

References

12 primary sources, each linked to its record. Figures quoted on this page were checked against the published abstract.