Peripheral Neuropathy

Regulation

• 38 C.F.R. § 3.303

  Direct service connection — a current disability linked to service. (Continuity of symptomatology under § 3.303(b) is limited by case law to the § 3.309(a) chronic diseases — Walker.)

Case law

• Shedden v. Principi, 381 F.3d 1163 (Fed. Cir. 2004)

  The three-element test: current disability, in-service event, and a nexus between them.

• Holton v. Shinseki, 557 F.3d 1363 (Fed. Cir. 2009)

  Federal Circuit restatement of the same three direct-service-connection elements.

• Caluza v. Brown, 7 Vet. App. 498 (1995)

  The evidentiary framework a rater weighs each element against.

• Walker v. Shinseki, 708 F.3d 1331 (Fed. Cir. 2013)

  Continuity of symptomatology (§ 3.303(b)) is available ONLY for a chronic disease listed in § 3.309(a); any other condition must use the medical-nexus pathway.

• Davidson v. Shinseki, 581 F.3d 1313 (Fed. Cir. 2009)

  A categorical 'a medical opinion is always required for nexus' is legal error — competent lay evidence can suffice.

• Jandreau v. Nicholson, 492 F.3d 1372 (Fed. Cir. 2007); Layno v. Brown, 6 Vet. App. 465 (1994)

  A veteran is competent to report symptoms they personally observe (Layno), and lay evidence can even establish a simple diagnosis in the right case (Jandreau).

• McLendon v. Nicholson, 20 Vet. App. 79 (2006)

  A LOW threshold — evidence that merely indicates a nexus MAY exist obligates VA to provide a C&P exam.

• 38 U.S.C. § 5107(b); Gilbert v. Derwinski, 1 Vet. App. 49 (1990)

  When the evidence is in relative equipoise, the tie goes to the veteran — the preponderance must be AGAINST the claim to deny it.

Regulation

• 38 C.F.R. § 3.310(a)

  A condition proximately caused by a service-connected condition (or by the treatment it requires).

• 38 C.F.R. § 3.310(b)

  A condition worsened beyond its natural progression by a service-connected condition.

Case law

• Wallin v. West, 11 Vet. App. 509 (1998)

  The three secondary elements: a current disability, a service-connected disability, and medical-nexus evidence linking them.

• Allen v. Brown, 7 Vet. App. 439 (1995)

  Secondary aggravation is compensable for the degree of worsening over the pre-aggravation baseline.

• El-Amin v. Shinseki, 26 Vet. App. 136 (2013)

  An opinion addressing only causation is inadequate where aggravation is also raised — the letter must speak to both prongs.

• Spicer v. McDonough, 61 F.4th 1360 (Fed. Cir. 2023)

  Expanded what qualifies (severity-worsening and treatment-based theories suffice; a § 3.310(b) baseline/permanence objection cannot defeat a but-for severity theory). Not a heightened standard.

• 38 U.S.C. § 5107(b); Gilbert v. Derwinski, 1 Vet. App. 49 (1990)

  When the evidence is in relative equipoise, the tie goes to the veteran — the preponderance must be AGAINST the claim to deny it.

Regulation

• 38 C.F.R. § 3.306 (38 U.S.C. § 1153)

  DIRECT aggravation: a pre-existing condition NOTED AT ENTRY that increased in disability during service — unless the increase is due to the natural progress of the disease. An in-service increase raises a PRESUMPTION of aggravation VA must rebut.

• 38 C.F.R. § 3.310(b)

  SECONDARY aggravation (a distinct branch): a non-service-connected condition worsened by an already service-connected condition — see Allen.

Case law

• Wagner v. Principi, 370 F.3d 1089 (Fed. Cir. 2004)

  If the condition was NOT noted at entry, the veteran is presumed sound; VA must rebut BOTH pre-existence and lack of aggravation by clear and unmistakable EVIDENCE (not the CUE error doctrine). If VA fails, the claim proceeds as ordinary DIRECT service connection — not as an aggravation claim.

• Horn v. Shinseki, 25 Vet. App. 231 (2012)

  That rebuttal burden never shifts back to the veteran — VA must rely on affirmative evidence of no aggravation.

• Hunt v. Derwinski, 1 Vet. App. 292 (1991); Davis v. Principi, 276 F.3d 1341 (Fed. Cir. 2002)

  Temporary flare-ups are not aggravation — the UNDERLYING condition (not just symptoms) must have worsened.

• Allen v. Brown, 7 Vet. App. 439 (1995)

  Compensation is for the measurable degree of worsening over the established baseline.

• 38 U.S.C. § 5107(b); Gilbert v. Derwinski, 1 Vet. App. 49 (1990)

  When the evidence is in relative equipoise, the tie goes to the veteran — the preponderance must be AGAINST the claim to deny it.