Part V, Subpart iii, Chapter 12, Section ANeurological Conditions and Convulsive Disorders

Revised February 26, 2025

V.iii.12.A.1.a#Considerations in SC for Neurological Disorders

See the table below for etiological considerations and manifestations involving specific neurological disorders.

V.iii.12.A.1.b#Identifying Epilepsy

Seizures must be witnessed or verified by a physician to warrant service connection (SC) for epilepsy. Verification may be by an electroencephalogram (EEG), which measures electrical activity in the brain. A physician does not have to witness an actual seizure before a diagnosis of epilepsy can be accepted for evaluation purposes. Verification by a physician based upon factors other than observing an actual seizure is sufficient.References:** For more information on

• identifying epilepsy, see 38 CFR 4.121, and
• psychomotor epilepsy, see 38 CFR 4.122.

V.iii.12.A.1.c#Evaluating Progressive Spinal Muscular Atrophy

Progressive muscular atrophy, 38 CFR 4.124a, diagnostic code (DC) 8023, refers to progressive spinal muscular atrophy, which is a disease of the spinal cord. Progressive muscular atrophy is subject to presumptive SC under 38 CFR 3.309(a) because it is an organic disease of the nervous system.

V.iii.12.A.1.d#Other Organic Diseases of the Nervous System Under 38 CFR 3.309(a)

For the purpose of establishing presumptive SC for a chronic disease under 38 CFR 3.307, the term other organic diseases of the nervous system in 38 CFR 3.309(a) includes any commonly recognized neurological disease (such as may be found in a valid contemporary medical treatise), which is not otherwise specifically enumerated under 38 CFR 3.309(a). This includes, but is not limited to , the following conditions:

• carpal tunnel syndrome
• migraine headaches
• sensorineural hearing loss
• tinnitus
• glaucoma
• progressive spinal muscular atrophy
• diseases of the cranial nervous system
• cranial nerve conditions, and
• peripheral nerve conditions, such as peripheral neuropathy.

Important: If there is uncertainty as to whether or not a claimed disability may be considered as an organic disease of the nervous system for purposes of 38 CFR 3.309(a), send the case to Compensation Service for guidance.
References: For more information on

• presumptive SC, see M21-1, Part V, Subpart ii, 2.B
• referring a claim to Compensation Service for an advisory opinion, see M21-1, Part X, Subpart v, 1.A.2, and
• establishing SC for hearing loss and tinnitus, see M21-1, Part V, Subpart iii, 2.B.

V.iii.12.A.1.e#SC of Vertigo

Carefully consider the evidence of record when deciding SC for vertigo. Vertigo is generally considered a symptom of another disability such as traumatic brain injury (TBI), Meniere's disease, vestibular neuritis/labyrinthitis, MS, stroke or tumor. When the disability manifested by vertigo is adequately identified, SC should be established for that diagnosis rather than for "vertigo." However, SC can be established for "vertigo" in the absence of a known or established underlying etiology if there is

• an event in service (such as a nonspecific diagnosis of vertigo in service)
• vertigo present post service
• a nexus establishing the vertigo post service is connected to the event in service, and
• the condition is not associated with any other disease or injury.

References: For more information on

• evaluating vertigo as a symptom of TBI and the prohibition against evaluating vertigo separately from TBI, see M21-1, Part V, Subpart iii, 12.B.2.d, and
• principles related to SC, see
  • 38 CFR 3.303, and
  • M21-1, Part V, Subpart ii, 2.

V.iii.12.A.1.f#Requesting Examinations for Manifestations of Central Nervous System Diseases

All manifestations or residuals of a central nervous system disease under 38 CFR 4.124a, DCs 8000-8025, must be examined using only the applicable disability benefits questionnaire (DBQ) for the primary or underlying central nervous system disease. Do not request a different DBQ specifically for any manifestations or residuals, as these are accounted for in the DBQ for the primary or underlying disease.Note: This applies in all cases where an examination is needed for such manifestations or residuals, even if the primary or underlying central nervous system disease itself is not at issue in the associated claim.Exception: When the disabling manifestation requires a specialist examination, as outlined in M21-1, Part IV, Subpart i, 2.A.6.a, request the specific DBQ for the condition requiring a specialist examination.Example: Do not request a Peripheral Nerves Conditions Disability Benefits Questionnaire for evaluation of extremity tremor and weakness due to Parkinson’s disease. Request only the Parkinson’s Disease Disability Benefits Questionnaire , which includes an assessment for impairment of the extremities.References: For more information on

• examination requests, see M21-1, Part IV, Subpart i, 2.A
• progressive neurological disorders, see M21-1, Part V, Subpart iii, 12.C, and
• DBQs, see the DBQ Switchboard.

2Peripheral Nerves

This topic contains information on evaluating peripheral nerves, including

• regulations for evaluating peripheral nerves
• 38 CFR 4.124a guidance on evaluating completely sensory peripheral nerve impairment
• assigning level of incomplete paralysis, neuritis, or neuralgia
• considering the complete findings when evaluating incomplete paralysis
• nerve branches of the lower extremities for which separate evaluations may be assigned
• assigning separate evaluations for lower extremity peripheral nerves
• determining individual nerves affected in the upper and lower extremities when evaluating disabilities
• electromyography (EMG) and other tests for peripheral nerve conditions
• applying the amputation rule to peripheral nerve disabilities, and
• evaluating restless legs syndrome.

Revised April 16, 2020

V.iii.12.A.2.a#Regulations for Evaluating Peripheral Nerves

38 CFR 4.124a, DCs 8510-8730, provides evaluation levels for complete paralysis, incomplete paralysis, neuritis, or neuralgia of peripheral nerves. At the beginning of the DCs for the peripheral nerves, the regulation also states that “incomplete paralysis” anticipates substantially less impaired function than described for complete paralysis of the nerve. When impairment is wholly sensory, the evaluation should be that specified for the mild , or at most, the moderate degree of incomplete paralysis for the nerve. The regulations listed below also provide guidance on evaluating peripheral nerves. 38 CFR 4.120 provides that when rating peripheral nerve injuries and residuals consider the relative impairment of motor function, trophic changes, and/or sensory disturbances. Attention should be given to the site and character of the injury. 38 CFR 4.123 provides several principles relating to peripheral nerves:

• Neuritis, characterized by loss of reflexes, muscle atrophy, sensory disturbances, and constant pain, is to be rated on the scale provided for injury of the nerve involved under the DCs and evaluations provided in 38 CFR 4.124a.
• The maximum evaluation for neuritis is the evaluation provided for severe incomplete paralysis of the affected nerve.
• The maximum evaluation that may be assigned for neuritis not characterized by the organic changes referred to in the regulation
  • is generally the evaluation level specified for moderate incomplete paralysis of the nerve, but
  • is the evaluation level specified for moderately severe impairment when the affected nerve is the sciatic nerve.

38 CFR 4.124 provides that the maximum evaluation for neuralgia, characterized usually by a dull and intermittent pain in the distribution of a nerve, should be the evaluation provided for moderate incomplete paralysis of the nerve under the applicable DC.

V.iii.12.A.2.b#38 CFR 4.124a Guidance on Evaluating Completely Sensory Peripheral Nerve Impairment

In cases where a peripheral nerve disability is only manifested by sensory impairment, 38 CFR 4.124a directs decision makers to assign the evaluation corresponding with the mild or at most the moderate degree of impairment. To make a choice between mild and moderate, consider the evidence of record and the following guidelines:

• The mild level of evaluation would be more reasonably assigned when sensory symptoms are
  • recurrent but not continuous
  • assigned a lower medical grade reflecting less impairment, and/or
  • affecting a smaller area in the nerve distribution.
• Reserve the moderate level of evaluation for the most significant and disabling cases of sensory-only involvement. These are cases where the sensory symptoms are
  • continuous
  • assigned a higher medical grade reflecting greater impairment, and/or
  • affecting a larger area in the nerve distribution.

Important: This provision does not mean that if there is any impairment that is non-sensory (or involves a non-sensory component) such as a reflex abnormality, weakness, or muscle atrophy, the disability must be evaluated as greater than moderate. Significant and widespread sensory impairment may potentially indicate the same or even more disability than a case involving a minimally reduced or increased reflex or minimally reduced strength.References:** For more information on

• evaluating wholly sensory manifestations of peripheral nerves, see Miller v. Shulkin, 28 Vet.App. 376 (2017)
• considering the complete findings when evaluating incomplete paralysis, see M21-1, Part V, Subpart iii, 12.A.2.d
• the importance of fully descriptive examinations and limitations from the disabling condition, see 38 CFR 4.1, and
• the importance of coordinating the evaluation with impairment of function based on sufficiently characteristic findings, see 38 CFR 4.21.

V.iii.12.A.2.c#Assigning Level of Incomplete Paralysis, Neuritis, or Neuralgia

The table below provides general guidelines for each level of incomplete paralysis of the upper and lower peripheral nerves.

Notes:

• Always consider the specific criteria in the 38 CFR 4.124a DC at issue, as well as the general guidance on neuritis and neuralgia under 38 CFR 4.123 and 38 CFR 4.124.

• This guidance also applies to radiculopathy, which is evaluated under a peripheral nerve code.

• Separate evaluations may not be assigned when evaluating an upper extremity peripheral nerve disability. See note under 38 CFR 4.124a, DC 8719.

Reference: For more information on evaluating peripheral nerves, see the Peripheral Nerve Evaluation Matrix.

V.iii.12.A.2.d#Considering the Complete Findings When Evaluating Incomplete Paralysis

Evaluation Builder entries must be based upon the complete findings of the DBQ and/or evidentiary record, including

• the nerve(s) involved
• whether the impairment involves
  • reduced or elevated sensation to various tests, or abnormal sensations
  • reduced or hyperactive reflexes
  • muscle weakness
  • muscle atrophy, and/or
  • trophic changes
• the amount of area in the nerve distribution affected by symptoms
• the frequency of symptoms, and
• the grade of any impairments that are identified.

Do not base the entries solely upon the examiner’s assessment of the level of incomplete paralysis. The examiner’s clinical assessment of the extent of incomplete paralysis, as indicated on the DBQ, may be inconsistent with or appear to contradict the objective findings that are documented in other sections of the DBQ or other evidence of record.Important: The rating activity, not the examining medical professional, determines whether the overall evidentiary record shows the severity of the condition meets the criteria for a classification of mild, moderate, moderately severe, or severe.Example 1: An examiner assesses the peripheral nerve disability as “mild incomplete paralysis.” However, the DBQ shows muscle weakness, atrophy, and diminished reflexes, which are clearly demonstrative of more than mild incomplete paralysis. In this case, the complete evidentiary record shows the condition is more than mild under guidance contained in 38 CFR 4.124 and therefore warrants a higher evaluation.Example 2: An examiner renders an assessment of “severe incomplete paralysis” when the objective test results are wholly sensory. Therefore, the condition warrants an evaluation no higher than moderate incomplete paralysis under 38 CFR 4.124a.References: For more information on

• tests for peripheral nerve conditions, see M21-1, Part V, Subpart iii, 12.A.2.h, and
• interpretation of examination reports, see 38 CFR 4.2.

V.iii.12.A.2.e#Nerve Branches of the Lower Extremities for Which Separate Evaluations May Be Assigned

The table below lists the five nerve branches of the lower extremities for which separate evaluations may be assigned. See M21-1, Part V, Subpart iii, 12.A.2.f for rating guidance on assigning separate evaluations for nerve conditions of the lower extremities. To assist in evaluating these nerves, the table below also includes any associated nerves in each branch, corresponding DCs under 38 CFR 4.124a, and the general functions covered by each nerve branch.

V.iii.12.A.2.f#Assigning Separate Evaluations for Lower Extremity Peripheral Nerves

Unlike the upper extremities, separate evaluations of the lower extremities may be assigned for symptoms that are separate and distinct, do not overlap, and are attributed to different lower extremity nerves. This means that separate evaluations are warranted when symptoms arise from any of the five nerve branches listed in the table in M21-1, Part V, Subpart iii, 12.A.2.e. If symptoms arise from within the same nerve branch of any of the five individual nerve branches in the lower extremity, separate evaluations for those symptoms are not warranted as this would constitute pyramiding.Example 1:Separate Evaluations Warranted A Veteran has severe incomplete paralysis of the common peroneal nerve and mild incomplete paralysis of the femoral nerve. Assign separate evaluations of 30 percent under 38 CFR 4.124a, DC 8521 and 10 percent under 38 CFR 4.124a, DC 8526.Analysis: The common peroneal nerve is part of the sciatic branch and the femoral nerve is part of the femoral branch. The functions for these branches are separate and distinct and therefore warrant separate evaluations.__E xample 2 :** Separate Evaluations Not Warranted_**A Veteran has severe incomplete paralysis of the common peroneal nerve under 38 CFR 4.124a, DC 8521 and moderate incomplete paralysis of the tibial nerve under 38 CFR 4.124a, DC 8524. In this case, a single 30-percent evaluation is assigned under 38 CFR 4.124a, DC 8521.Analysis: Both of these nerves are part of the same sciatic branch, and therefore the functions associated with these nerves are not separate and distinct. The 30-percent evaluation shall be assigned under 38 CFR 4.124a, DC 8521 since it represents the predominant disability.References: For more information on

• separate evaluations and pyramiding, see M21-1, Part V, Subpart ii, 3.D.2.b, and
• nerve branches of the lower extremities, see M21-1, Part V, Subpart iii, 12.A.2.e.

V.iii.12.A.2.g#Determining Individual Nerves Affected in the Upper and Lower Extremities When Evaluating Disabilities

When evaluating peripheral nerve disabilities of the upper and lower extremities, the rating activity must conduct a thorough review of the medical evidence of record to determine the individual nerve(s) affected. Department of Veterans Affairs (VA) examiners are required, to the extent possible, to select the individual nerves affected when completing DBQs. However, the examiner may not necessarily conduct a review of all previous clinical records or perform comprehensive tests to pinpoint the exact nerve and/or symptoms attributable to that nerve. Important:**

• It is the responsibility of the rating activity, in accordance with 38 CFR 4.2, to interpret the DBQ along with the whole recorded history, and accurately identify and assess the current level of peripheral nerve disability. This includes identifying the appropriate nerve from a review of the evidence so that the appropriate evaluation can be assigned.
• Include the following language in all peripheral nerves examination requests:

Examiner: Please identify the specific nerve(s) affected. If you are unable to identify the specific nerve(s), please provide a rationale in the Remarks section. Thank you. Follow the guidance in the table below when reviewing medical evidence pertaining to peripheral nerve disabilities of the upper and lower extremities.

Exception: Where the disability at issue is lower extremity radiculopathy associated with service-connected (SC) thoracolumbar disability, follow the guidance in M21-1, Part V, Subpart iii, 1.B.3.d and evaluate using 38 CFR 4.124a, DC 8520 (the sciatic nerve).

Note: The nerve branches and general functions of the nerve branches of the lower extremities are described in the table found in M21-1, Part V, Subpart iii, 12.A.2.e.

V.iii.12.A.2.h#EMG and Other Tests for Peripheral Nerve Conditions

Electromyography (EMG) results are required for evaluations of peripheral nerve disabilities unless there is a previous EMG test of record or the record contains sufficient clinical evidence to determine the extent of paralysis in the peripheral nerve. As noted in the Peripheral Nerves Conditions (Not Including Diabetic Sensory - Motor Peripheral Neuropathy) Disability Benefits Questionnaire , EMG studies are usually rarely required to diagnose specific peripheral nerve conditions in the appropriate clinical setting and, if EMG studies are in the medical record and reflect the Veteran's current condition, repeat studies are not indicated. Important: Ultimately, it is the role of the rating activity to determine if the examination was sufficient to confirm the question and extent of peripheral nerve involvement.Note: Other clinical findings that may be sufficient to document a peripheral nerve disability include

• sensation to light touch testing
• deep tendon reflex testing
• certain signs for the median nerve
• trophic changes
• gait testing
• muscle strength testing, and
• the presence of muscle atrophy.

V.iii.12.A.2.i#Applying the Amputation Rule to Peripheral Nerve Disabilities

In determining whether the amputation rule under 38 CFR 4.68 applies to peripheral nerve evaluations, decision makers must consider the etiology of the peripheral nerve disability. If the peripheral nerve disability is associated with a musculoskeletal injury or amputation, follow the guidance in M21-1, Part V, Subpart iii, 1.E.2.j regarding the application of the amputation rule. When peripheral nerve disabilities are not associated with a musculoskeletal injury, such as diabetic neuropathy, the amputation rule does not apply. Reference: For more information on evaluating peripheral nerve injuries associated with a muscle injury, see 38 CFR 4.55.

V.iii.12.A.2.j#Evaluating Restless Legs Syndrome

Restless legs syndrome is a neurological disorder characterized by throbbing, pulling, creeping, or other unpleasant sensations in the legs and an uncontrollable, and sometimes overwhelming, urge to move them. Symptoms occur primarily at night when a person is relaxing or at rest and can increase in severity during the night. Restless legs syndrome should be rated under the appropriate peripheral nerve DC(s) that most closely approximates the area of the extremity or extremities affected by the distribution of the symptoms.

3Migraine Headaches

This topic contains information on migraine headaches, including

• evaluation criteria for migraine headaches
• DC 8100 terminology: prostrating and completely prostrating
• role of medical evidence in establishing the fact of prostration
• lay evidence of prostration from migraine headaches
• DC 8100 terminology:
  • severe economic inadaptability , and
  • less frequent and very frequent
• frequency determinations: types of proof, and
• headache journals.

Revised September 14, 2023

V.iii.12.A.3.a#Evaluation Criteria for Migraine Headaches

Migraine headaches are evaluated under the criteria of 38 CFR 4.124a, DC 8100. Evaluations depend primarily on the frequency of attacks and the degree to which symptoms are prostrating. The extent to which the headaches cause work impairment is also a factor and is considered for the 50-percent evaluation.Important: The Court of Appeals for Veterans Claims, in Holmes v. Wilkie, 33 Vet.App. 67 (2020), held that the criteria of 38 CFR 4.124a, DC 8100, contemplate more than merely headache symptoms, and that the DC requires VA to

• consider all symptoms experienced as a result of migraine attacks, and
• evaluate those symptoms based on the overall frequency, severity, and economic impact of the migraine attacks.

Example: A Veteran suffers SC migraine headaches that occur twice weekly and are prostrating in nature. Symptoms manifested during the migraine headache attacks include frontal headaches, photophobia, nausea, and dizziness. In evaluating the disability under 38 CFR 4.124a, DC 8100, VA must consider all symptoms associated with the migraine headache attacks, and not just the headaches themselves.

V.iii.12.A.3.b#DC 8100 Terminology: Prostrating and Completely Prostrating

Prostrating , as used in 38 CFR 4.124a, DC 8100, means “causing extreme exhaustion, powerlessness, debilitation or incapacitation with substantial inability to engage in ordinary activities.” Completely prostrating** , as used in 38 CFR 4.124a, DC 8100, means extreme exhaustion or powerlessness with essentially total inability to engage in ordinary activities.

V.iii.12.A.3.c#The Role of Medical Evidence in Establishing the Fact of Prostration

Although prostration is substantially defined by how the disabled individual subjectively feels and functions when having migraine headache symptoms, medical evidence is required to establish that the reported symptoms are due to the SC migraine headaches. The following is an example of a medical statement that would ordinarily establish the fact of prostration if the medical report and the history provided by the claimant are both credible._ __The patient reports symptoms of severe head pain, blurred vision, nausea and vomiting, and being unable to tolerate light or noise, worsened by most activities including reading, writing, and engaging in conversations or physical activities. When experiencing these symptoms, the patient only sleeps or rests. The symptoms reported by the patient are consistent with the diagnosis of migraine headaches and the reported limitations are consistent with those seen in patients suffering from migraine headaches of similar clinical severity. ___Note : Medical reports may not use the word “prostration.” However, this is an adjudicative determination based on the extent to which the facts meet the definition of the term.

V.iii.12.A.3.d#Lay Evidence of Prostration from Migraine Headaches

A claimant’s own testimony regarding symptoms and limitations when having those symptoms can establish prostration as long as the testimony is credible and symptoms are otherwise competently attributed to migraine headaches through medical evidence. Example: A claimant provides testimony that she 1) experiences severe headaches and vomiting when exposed to light; 2) does not engage in any activities when this occurs; and 3) must rest or sleep during these episodes. If there is medical evidence that the claimant’s description of symptoms is in fact symptoms of migraine headaches, a determination that the headaches cause prostration can be made.Reference: For more information on competency of lay testimony, see

• M21-1, Part V, Subpart ii, 1.B, and
• Espiritu v. Derwinski, 2 Vet.App. 492 (1992).

V.iii.12.A.3.e#DC 8100 Terminology: Severe Economic Inadaptability

Severe economic inadaptability denotes a degree of substantial work impairment. It does not mean the individual is incapable of any substantially gainful employment. Evidence of work impairment includes, but is not necessarily limited to, the use of sick leave or unpaid absence.Note: In cases where migraine headaches meet the criterion of severe economic inadaptability and, additionally, the evidence shows that the claimant is incapable of substantially gainful employment due to the headaches, referral for consideration of an extraschedular award of a total evaluation based on individual unemployability is appropriate.Reference: For more information on severe economic inadaptability, see Pierce v. Principi , 18 Vet.App 440 (2004).

V.iii.12.A.3.f#DC 8100 Terminology: Less Frequent and Very Frequent

38 CFR 4.124a, DC 8100 does not define the terms less frequent for the 0- percent criterion or very frequent for the 50-percent criterion. However, the overall rating criteria structure for migraine headaches provides a basis for guidance. As noted in 38 CFR 4.124a, DC 8100, the 10-percent evaluation specifies average frequency (“averaging one in 2 months over the last several months”), which is half of what is required for a 30-percent evaluation (“on average once a month over the last several months”). For definitions of the terms less frequent and very frequent , refer to the table below. — Term — Evaluation Level — Definition less frequent — 0 percent — Characteristic prostrating attacks, on average, are more than two months apart over the last several months. very frequent — 50 percent — Characteristic prostrating attacks, on average, are less than one month apart over the last several months.

V.iii.12.A.3.g#Frequency Determinations: Types of Proof

Frequency of migraine headache attacks or episodes is a factual determination. Analyze all evidence in the record bearing on the question. Probative evidence may include

• medical progress notes
• competent and credible lay evidence on how often the claimant experiences symptoms (as long as those symptoms have been competently identified as symptoms of migraine headaches)
• contemporaneous notes (a headache journal)
• prescription refills, and
• witness statements.

Note: The absence of treatment reports is not necessarily probative on the question of headache frequency as a claimant may not seek treatment for headaches during every episode.Reference:** For more information on evaluating evidence, including competency and credibility, see M21-1, Part V, Subpart ii, 1.

V.iii.12.A.3.h#Headache Journals

Headache journals, which routinely and relatively contemporaneously record headache episodes, may be accepted as credible lay testimony regarding

• headache frequency
• prostration, and
• occupational impairment (for example, sick leave due to headaches).

Note: Headaches recorded on non-work days may be used to prove frequency and prostration. However, they will not generally be relevant to work availability, and performance or limitations, which are considerations in determining severe economic inadaptability.