Citation Nr: 21002852 Decision Date: 01/15/21 Archive Date: 01/15/21 DOCKET NO. 13-31 848 DATE: January 15, 2021 ORDER Entitlement to service connection for peripheral neuropathy (PN) of the left upper extremity, to include as due to in-service herbicide agent exposure, is denied. Entitlement to service connection for PN of the right upper extremity, to include as due to in-service herbicide agent exposure, is denied. Entitlement to service connection for PN of the left lower extremity, to include as due to in-service herbicide agent exposure, is denied. Entitlement to service connection for PN of the right lower extremity, to include as due to in-service herbicide agent exposure, is denied. Entitlement to service connection for a sleep disability, to include as secondary to a service-connected disability, is denied. FINDINGS OF FACT 1. The Veteran’s PN of the left upper extremity was not shown in-service or manifest to a compensable degree within a year post-service, was not shown for many years following service, and is not etiologically related to an event, disease, or injury of service origin. 2. The Veteran’s PN of the right upper extremity was not shown in-service or manifest to a compensable degree within a year post-service, was not shown for many years following service, and is not etiologically related to an event, disease, or injury of service origin. 3. The Veteran’s PN of the left lower extremity was not shown in-service or manifest to a compensable degree within a year post-service, was not shown for many years following service, and is not etiologically related to an event, disease, or injury of service origin. 4. The Veteran’s PN of the right lower extremity was not shown in-service or manifest to a compensable degree within a year post-service, was not shown for many years following service, and is not etiologically related to an event, disease, or injury of service origin. 5. The Veteran’s contended sleep condition was not shown in-service and is not etiologically related to an event, disease, or injury of service origin, and because the Veteran’s PN of the bilateral upper extremities and bilateral lower extremities has not been granted service connection, the Veteran’s contended sleep disability secondary to PN cannot be established. CONCLUSIONS OF LAW 1. The criteria for entitlement to service connection for PN of the left upper extremity, to include as due to in-service herbicide agent exposure, have not been met. 38 U.S.C. §§ 1110, 1112, 1113; 38 C.F.R. §§ 3.303, 3.307, 3.309. 2. The criteria for entitlement to service connection for PN of the right upper extremity, to include as due to in-service herbicide agent exposure, have not been met. 38 U.S.C. §§ 1110, 1112, 1113; 38 C.F.R. §§ 3.303, 3.307, 3.309. 3. The criteria for entitlement to service connection for PN of the left lower extremity, to include as due to in-service herbicide agent exposure, have not been met. 38 U.S.C. §§ 1110, 1112, 1113; 38 C.F.R. §§ 3.303, 3.307, 3.309. 4. The criteria for entitlement to service connection for PN of the right lower extremity, to include as due to in-service herbicide agent exposure, have not been met. 38 U.S.C. §§ 1110, 1112, 1113; 38 C.F.R. §§ 3.303, 3.307, 3.309. 5. The criteria for entitlement to service connection for a sleep disability, to include as secondary to a service-connected disability, have not been met. 38 U.S.C. § 1110; 38 C.F.R. §§ 3.303, 3.304, 3.310. REASONS AND BASES FOR FINDINGS AND CONCLUSIONS The Veteran served on active duty from August 1966 to September 1968. These matters return to the Board of Veterans’ Appeals (Board) on appeal from a December 2011 rating decision issued by the Department of Veterans’ Affairs (VA) Regional Office (RO) in Detroit, Michigan. By way of background, the Board previously remanded these matters for additional development in October 2015 and July 2018. Included in the October 2015 remand were directives pertaining to the issues of entitlement to service connection for hypertension and a total disability evaluation based on individual unemployability (TDIU) due to service-connected disabilities. Said issues, however, are no longer in appellate status as they were not timely perfected for appeal to the Board. See Smallwood v. Brown, 10 Vet. App. 93, 97 (1997); see also In re Fee Agreement of Cox, 10 Vet. App. 361, 374 (1997) (holding that if the claims file does not contain a notice of disagreement, a statement of the case and a VA Form 9 (substantive appeal), the Board is not required, and in fact, has no authority, to decide the claim). As will be discussed in more detail below, the Board finds substantial compliance has been met with the July 2018 remand directives. See Stegall v. West, 11 Vet. App. 268, 271 (1998) (holding when a remand is issued, the Veteran is entitled, as a matter of law, the right to compliance with the remanded order). The Board has limited the discussion below to the relevant evidence required to support its finding of fact and conclusion of law, as well as to the specific contentions regarding the case as raised directly by the Veteran and those reasonably raised by the record. See Scott v. McDonald, 789 F.3d 1375, 1381 (Fed. Cir. 2015); Robinson v. Peake, 21 Vet. App. 545, 552 (2008). Service Connection Service connection may be granted for a disability resulting from personal injury suffered or disease contracted in the line of duty, or for the aggravation of a pre-existing injury or disease in the line of duty. 38 U.S.C. § 1110; 38 C.F.R. § 3.303(a). Veterans who, during active service, served in the Republic of Vietnam during the period beginning on January 9, 1962, and ending on May 7, 1975, shall be presumed to have been exposed to an herbicide agent, unless there is affirmative evidence of non-exposure. 38 U.S.C. § 1116; 38 C.F.R. § 3.307. If a Veteran was exposed to an herbicide agent (to include Agent Orange) during active military, naval or air service and has contracted an enumerated disease to a degree of 10 percent or more at any time after service, the Veteran is entitled to a presumption of service connection even though there is no record of such disease during service. 38 U.S.C. § 1112; 38 C.F.R. §§ 3.307, 3.309(e). The list of diseases associated with exposure to certain herbicide agents includes early-onset PN. 38 C.F.R. § 3.309(e). The Veteran is entitled to have been presumed exposed to herbicide agents during his verified service in Vietnam during the relevant time period under 38 C.F.R. § 3.307. Where a Veteran served continuously for 90 days or more during a period of war, or during peacetime service after December 31, 1946, and an organic disease of the nervous system, such as PN, becomes manifest to a degree of 10 percent within one year from date of termination of such service, such disease shall be presumed to have been incurred in or aggravated by service, even though there is no evidence of such diseases during the period of service. This presumption is rebuttable by affirmative evidence to the contrary. 38 U.S.C. §§ 1101, 1112, 1113, 1137; 38 C.F.R. §§ 3.307, 3.309. See also Fountain v. McDonald, 27 Vet. App. 258, 271 (2015). Evidence of continuity of symptomatology from the time of service until the present is required where the chronicity of a chronic condition manifested during service either has not been established or might reasonably be questioned. 38 C.F.R. § 3.303(b); see also Walker v. Shinseki, 708 F.3d 1331, 1340 (Fed. Cir. 2013) (holding that only conditions listed as chronic diseases in § 3.309(a) may be considered for service connection under 38 C.F.R. § 3.303(b)). In the event a Veteran has at least one service-connected disability, he or she may be entitled to benefits based on a secondary service connection. In order to establish a secondary service connection, the Veteran must show: (1) a current disability that is not already service-connected; (2) at least one service-connected disability; and, (3) evidence that the non-service-connected disability is either proximately due to or aggravated beyond its natural progression by a service-connected disability. 38 C.F.R. § 3.310; Allen v. Brown, 7 Vet. App. 439, 444 (1995). When service connection cannot be established on a presumptive or secondary basis, the Court has held that the claim must nevertheless be reviewed to determine whether service connection can be established on a direct basis. See Combee v. Brown, 34 F.3d 1039 (1994). The elements of direct service connection are: “(1) the existence of a present disability; (2) in-service incurrence or aggravation of a disease or injury; and (3) a causal relationship between the present disability and the disease or injury incurred or aggravated during service,” also known as the nexus element. Shedden v. Principi, 381 F.3d 1163, 1167 (Fed. Cir. 2004). 1. Entitlement to service connection for PN of the left upper extremity, to include as due to in-service herbicide agent exposure, is denied. 2. Entitlement to service connection for PN of the right upper extremity, to include as due to in-service herbicide agent exposure, is denied. The Veteran contends his PN of the bilateral upper extremities was caused by service including herbicide agent exposure. The Board finds service connection is not warranted. Upon entrance, the Veteran declined experiencing problems with his upper extremities. See May 1966 entrance examination. During service, treatment records lack reference to any symptoms, treatment, or diagnosis related to PN in the upper extremities. At separation, the Veteran declined experiencing upper extremity problems. See July 1968 separation examination. The Veteran stated that his PN symptoms began in his hands “very soon after” discharge. See March 2013 Statement in Support of Claim. Then, the numbness and pins and needles increased in severity in the 1970s. Id. Elsewhere, the Veteran stated that he began experiencing chronic numbness and tingling in his hands in the early 1970s. See November 2011 Statement in Support of Claim. He stated that by the 1990s, he had to seek treatment due to his worsened symptoms. Id. Since then, he has continued to experience symptoms. Id. During this time, the Veteran noted that he published trade magazines that he then distributed. Id. In 1998, during a neurological appointment for feet problems including pain and paresthesias, the Veteran declined experiencing upper extremity symptoms. See May 1998 non-government treatment records. In 2003, the Veteran reported numbness, paresthesias, and discomfort in his fingers and hands. See October 2003 non-government treatment records. Upon review, the provider noted that the Veteran had a history of neuropathy that was diagnosed “a number of years ago.” Id. It was noted that he never had an EMG. Id. The provider noted that the Veteran’s neuropathy is a small fiber neuropathy. Id. The Veteran had a cervical spine MRI in December 2003 following complaints of burning and numbness in his hands. See December 2003 treatment records. In 2006, the Veteran reported that he began to experience symptoms of pain, numbness, and tingling in his hands in approximately 1975 to 1977. See October 2006 non-government treatment record. He stated that the tingling paresthesias in the hands at some point changed to a dull ache. Id. Upon examination, the provider determined that the Veteran had small fiber neuropathy noted in the lower extremities. Id. Regarding the hands, the provider stated that he has pain in his hands that sometimes awakens him at night and at other times is simply more noticeable at night. Id. He works with his hands. Id. The provider recommended treatment empirically for “what sounds like carpal tunnel syndrome.” Id. In 2016, the Veteran conveyed a history of paresthesias and hypersensitivity in both hands up to the wrists. See September 2016 VA treatment records. EMG and NCS testing revealed moderate sensory motor neuropathy involving “lower extremities more than upper extremities” and “bilateral distal median dysfunction – carpal tunnel syndrome, moderate to severe on the right side and moderate on the left side. See September 2016 VA treatment records. The Veteran was afforded a VA examination in September 2016 to determine the nature and etiology of his upper extremity PN. The examiner noted the Veteran has idiopathic progressive neuropathy diagnosed in 2016 and bilateral carpal tunnel syndrome diagnosed in 2016. See September 2016 VA examination. The examiner noted the Veteran’s reports of numbness, tingling, and hands “falling asleep” beginning the 1970s with worsening symptoms over the years. Id. The examiner opined that the Veteran’s bilateral upper extremity PN is less likely as not related to military service and herbicide agent exposure. Id. The examiner reasoned that while the VA has recognized a positive association exists between herbicide agent exposure and acute and subacute PN, this refers to transient PN that appears within weeks or months of exposure to an herbicide agent and resolves within two years of the date of onset. Id. In the Veteran’s case, the examiner found no complaints of, treatment for, or diagnosis of PN in the service treatment records or within two years of presumed last exposure to herbicide agents. Id. Further, the Veteran’s PN is continuous and therefore does not meet the criteria definition of acute or subacute PN associated with herbicide agent exposure. Id. The examiner also explained that the Veteran has an occupational history of work requiring repetitive wrist motion, which increases the risk of developing carpal tunnel syndrome as diagnosed in the EMG. Id. A September 2016 VA addendum opinion stated given the Veteran’s herbicide agent exposure and the clinical course of his PN, it “could be” due to herbicide agent exposure unless another etiology could be proven. See September 2016 VA addendum. Another addendum opinion was obtained in August 2019 wherein the examiner opined that the Veteran’s bilateral upper extremity PN is less likely as not due to or the result of his active duty service including presumed herbicide agent exposure. See August 2019 VA addendum. The examiner reasoned that the Veteran’s PN of the upper extremities does not meet the criteria for PN due to herbicide agent exposure repeating the rationale from the initial examination in September 2016. Id. The examiner then further opined that the Veteran’s latent PN was not diagnosed during service or in the immediate years following separation. Id. The examiner stated that the Veteran was 52 years old when he was evaluated for neuropathy in 1998 in relation to his feet, which was 30 years following service and too remote from discharge. Id. Further, the Veteran’s PN is isopathic, which is common etiology and is consistent with his age and symptoms. Id. Medical records indicate symptoms could have begun in the 1990s which is when the Veteran was in his 50s, correlating with idiopathic neuropathy. Id. The examiner cited to multiple articles discussing idiopathic neuropathy including one indicating that most cases present in adults 50 years of age and progress slowly over months to years presenting typically with sensory symptoms of parasthesia, numbness, and pain. Id. Additionally, the Veteran’s occupation required repetitive motion of the wrist and he was diagnosed with bilateral carpal tunnel confirmed by EMG. Id. The examiner stated that this was related to his post-military occupation. Id. A medical article was cited in support thereof stating that risk factors for carpal tunnel syndrome include occupational biomechanical factors involving the hands and wrist, particularly repetition, forceful exertion, and vibration. Id. The Veteran has a current diagnosis of PN of the bilateral upper extremities diagnosed in 2016. This disability, however, does not meet the presumptive requirements regarding herbicide agent exposure or chronic conditions. The Veteran has presented conflicting statements regarding the onset of his symptoms. In one instance, he stated that his symptoms began during service and worsened since separation. Later, the Veteran stated that his PN upper extremity symptoms began sometime in the 1970s and worsened thereafter. Of note, the Veteran’s service treatment records lack complaints of his described symptoms including pain, numbness, tingling and any other symptoms related to the upper extremities. Similarly, his separation examination notes normal upper extremities and did not include complaints of numbness, tingling, pain, or any other PN symptoms. In fact, upon review, the Veteran declined experiencing upper extremity PN symptoms in 1998 during a neurological consult for PN symptoms related to the feet. Documented complaints of upper extremity PN symptoms were not found until 2003 when the Veteran reported numbness, paresthesias, and discomfort in his fingers and hands. While the Veteran is competent to report his symptoms, the Board finds his reports that said symptoms began in service are not credible or supported by the evidence of record. Rather, the Board finds the Veteran competently and credibly reported his upper extremity PN symptoms in 2003 which are corroborated by the record. Thus, the Board assigns more probative value to the documented medical evidence of record noting the Veteran’s symptoms of upper extremity PN in 2003 than the statements made in connection with a claim for benefits. The Board also assigns more probative value to the Veteran’s service treatment records and separation examination reflecting a lack of complaints related to the upper extremities and PN during service or at separation. The Veteran was formally diagnosed with upper extremity PN through testing in 2016 with symptoms first noted in 2003, both of which are decades outside of service and decades outside the required manifestation period for chronic conditions. Thus, the Veteran’s upper extremity PN cannot fall under continuity of symptomatology because the Veteran’s reported symptoms and diagnoses occurred multiple decades after separation from service. In order for the presumptions related to herbicide agent exposure to apply when the early-onset peripheral neuropathy was not noted in-service, the disease must have manifested to a degree of 10 percent or more within a year after the last date on which the Veteran was exposed to an herbicide agent. The Veteran separated from active duty in September 1968. As noted above, it was not until 2016 that the Veteran was diagnosed with upper extremity PN with symptoms documented in 2003. Even considering on-set of 2003, this is decades beyond the one-year manifestation period following exposure under 38 C.F.R. § 3.307. Therefore, the presumption under 38 C.F.R. § 3.309 for herbicide agent exposure is not applicable for the Veteran’s upper extremity PN. Service connection may still be awarded on a direct basis. The question for the Board is whether the Veteran’s upper extremity PN was caused by or incurred during service including due to herbicide agent exposure. Upon review, a nexus to service has not been established. The Board finds the September 2016 VA examination and August 2019 VA addendum opinion include consideration of the Veteran’s medical history and set forth all pertinent findings, such that the Board is able to make a fully informed decision. See Stefl v. Nicholson, 21 Vet. App. 120, 123 (2007). When considered together and with the entire evidence of record, the Board finds the examination report and addendum adequate for adjudication of the Veteran’s service connection claim because they are based upon an accurate medical history and provide explanations that contain clear conclusions and supporting data. Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 304 (2008); see also Barr v. Nicholson, 21 Vet. App. 303, 312 (2007) (once VA undertakes to provide a medical examination or opinion, it must ensure that the examination or opinion is adequate). With regards to the September 2016 VA addendum opinion, the Board finds this opinion not adequate as it fails to address whether it is at least as likely as not the Veteran’s upper extremity PN was caused by his herbicide agent exposure during service and it fails to provide sufficient rationale as to why it “could be” due to herbicide agent exposure. See Ardison v. Brown, 6 Vet. App. 405, 407 (1994) (finding an adequate medical opinion must be based upon a consideration of the Veteran’s prior medical history and must describe the Veteran’s condition in sufficient detail so as to allow the Board to make a fully informed evaluation); see also Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 301 (2008) (holding the opinion must “contain not only clear conclusions with supporting data, but also a reasoned medical explanation connecting the two”). Thus, the Board assigns more probative value to the adequate medical opinion and addendum of record. The Veteran’s representative contends that herbicide agent exposure can cause delayed-onset PN. See December 2020 Appellate Brief. In this case, however, the August 2019 VA examiner specifically considered whether the Veteran’s upper extremity PN was caused by herbicide agent exposure. The examiner attributed the Veteran’s upper extremity PN to his carpal tunnel syndrome that was more likely caused by his repeated wrist movements in his post-separation occupation and that his PN is idiopathic and related to his age. The Board finds this to be highly probative because the examiner specifically considered the Veteran’s symptoms and history in relation to his herbicide agent exposure during service. While the Veteran believes peripheral neuropathy of the upper extremities is caused by herbicide agent exposure, he is not competent to provide a nexus opinion in this case. This issue is medically complex, as it requires specialized medical knowledge. Jandreau v. Nicholson, 492 F.3d 1372, 1377 (Fed. Cir. 2007). Thus, the Board gives more probative weight to the competent medical evidence. The Veteran also contended that his fellow service members experienced similar symptoms in relation to his PN. Unfortunately, however, this contention does not apply to the facts and circumstances of the Veteran’s specific case or provide competent and credible evidence to establish a causative relationship between the Veteran’s service and his upper extremity PN. Based on the aforementioned, the Board finds the preponderance of the evidence is against an award of service connection for PN of the left and right upper extremities. As such, the benefit-of-the-doubt doctrine is not for application and the claim must be denied. 38 U.S.C. § 5107 (b); see also Gilbert v. Derwinski, 1 Vet. App. 49, 57 (1990). 3. Entitlement to service connection for PN of the left lower extremity, to include as due to in-service herbicide agent exposure, is denied. 4. Entitlement to service connection for PN of the right lower extremity, to include as due to in-service herbicide agent exposure, is denied. The Veteran contends his PN of the bilateral lower extremities was caused by service including herbicide agent exposure. The Board finds service connection is not warranted. Upon entrance, the Veteran declined experiencing problems with his lower extremities. See May 1966 entrance examination. During service, treatment records lack reference to any symptoms, treatment, or diagnosis related to PN in the lower extremities. At separation, the Veteran declined experiencing lower extremity problems. See July 1968 separation examination. The Veteran reported experiencing numbness and burning in his feet beginning in the mid-1980s. See November 2010 Statement in Support of Claim. In 1998, the Veteran reported experiencing problems with his feet for “several years.” See May 1998 non-government treatment records. He stated that for the past three years he noticed pain and paresthesia in both feet from the ankles down. Id. Symptoms included burning, itching, aching, and tickling of both the dorsal and plantar surface on both feet. Id. In 2000, following a neurologic assessment for continued symptoms, the provider stated that the Veteran’s feet paresthesias are suggestive of PN; however, the impression had not been proven with scientific neurologic testing. See December 2000 non-government treatment records. The provider noted the requested MRI in 1998 that remained incomplete. Id. In 2003, the Veteran complained of burning and numbness in his feet. See December 2003 non-government treatment records. He stated that the symptoms spread from his toes to the balls of his feet. See October 2003 non-government treatment records. Upon examination, the provider reported that the Veteran had a history of neuropathy and was first diagnosed a number of years ago without EMG testing. Id. In 2006, the Veteran reported he began experiencing pain, numbness, and tingling in his feet fifteen years prior, about 1990. See October 2006 non-government treatment records. He was referred to neurology to rule out PN. Id. Upon examination, the provider noted that his feet dysesthesias and paresthesias sounded like PN, but he had a normal neurologic examination except for brisk reflexes in the legs. Id. He stated that although the Veteran’s symptoms sounded neuropathic in nature, the brisk reflexes would be inconsistent, and as such, the provider recommended an MRI for further diagnostic testing. Id. The Veteran, however, did not complete an MRI. Id. In 2016, the Veteran reported a long history of painful dysesthesias in both feet that progressed up to mid-lower legs. See September 2016 VA treatment records. EMG and NCS testing revealed moderate sensory motor neuropathy involving “lower extremities more than upper extremities.” See September 2016 VA treatment records. The Veteran was afforded a VA examination to determine the nature and etiology of his bilateral lower extremity PN which occurred in August 2016. The examiner noted the Veteran was diagnosed with idiopathic progressive neuropathy in 2016. See August 2016 VA examination. The Veteran reported developing bilateral foot burning, pain, and numbness in the early to mid-1980s but did not seek medical attention until the 1990s. Id. The examiner opined that the Veteran’s bilateral lower extremity PN was less likely as not related to military service and herbicide agent exposure. Id. The examiner reasoned that while the VA has recognized a positive association exists between herbicide agent exposure and acute and subacute PN, this refers to transient PN that appears within weeks or months of exposure to an herbicide agent and resolves within two years of the date of onset. Id. In the Veteran’s case, the examiner found no complaints of, treatment for, or diagnosis of PN in the service treatment records or within two years of presumed last exposure to herbicide agents. Id. Further, the Veteran’s PN is continuous and therefore does not meet the criteria definition of acute or subacute PN associated with herbicide agent exposure. Id. A September 2016 VA addendum opinion stated given the Veteran’s herbicide agent exposure and the clinical course of his PN, it “could be” due to herbicide agent exposure unless another etiology could be proven. See September 2016 VA addendum. Another addendum opinion was obtained in August 2019 wherein the examiner opined that the Veteran’s bilateral lower extremity PN is less likely as not due to or the result of his active duty service including presumed herbicide agent exposure. See August 2019 VA addendum. The examiner reasoned that the Veteran’s PN of the lower extremities does not meet the criteria for PN due to herbicide agent exposure repeating the rationale from the initial examination in September 2016. Id. The examiner then further opined that the Veteran’s latent PN was not diagnosed during service or in the immediate years following separation. Id. The examiner stated that the Veteran was 52 years old when he was evaluated for neuropathy in 1998 in relation to his feet, which was 30 years following service. Id. The examiner stated that the Veteran’s complaints related to PN of the lower extremities were too remote from military discharge. Id. Further, the Veteran’s PN is isopathic, which is common etiology and is consistent with his age and symptoms. Id. Medical records indicate symptoms could have begun in the 1990s which is when the Veteran was in his 50s, correlating with idiopathic neuropathy. Id. The examiner cited to multiple articles discussing idiopathic neuropathy including one indicating that most cases present in adults 50 years of age and progress slowly over months to years presenting typically with sensory symptoms of parasthesia, numbness, and pain. Id. The Veteran has PN of the bilateral lower extremities diagnosed in 2016. This disability, however, does not meet the presumptive requirements regarding herbicide agent exposure or chronic conditions. The Veteran’s onset of PN symptoms in the lower extremities is inconsistent throughout the record. In one instance, he reported PN symptoms in the lower extremities began in the mid-1980s. Later, in 1998, he stated that he experienced symptoms for “several years” which he then noted to be three years prior, 1995. Of note, the Veteran’s service treatment records lack complaints of his described PN symptoms in the lower extremities. Similarly, his separation examination notes normal lower extremities and did not include complaints of numbness, tingling, pain, or any other PN symptoms. In fact, documented complaints within the Veteran’s treatment records of lower extremity PN symptoms were not found until 1998 during which the Veteran stated the symptoms began approximately three years earlier, 1995. Recognizing the Veteran is competent to report symptoms, the Board finds this evidence to be highly probative regarding symptom onset. The Board relies upon this onset date rather than the timeframe the Veteran reported in connection with his claim for benefits. Assuming onset of approximately 1995, the chronic condition presumptions cannot apply because it is decades outside of the required manifestation period. Thus, the Veteran’s lower extremity PN cannot fall under continuity of symptomatology because the Veteran’s reported symptoms and diagnoses occurred multiple decades after separation from service. In order for the presumptions related to herbicide agent exposure to apply when the early-onset peripheral neuropathy was not noted in-service, the disease must have manifested to a degree of 10 percent or more within a year after the last date on which the Veteran was exposed to an herbicide agent. The Veteran separated from active duty in September 1968. As noted above, it was not until 2016 that the Veteran was diagnosed with lower extremity PN with symptoms reportedly beginning in 1995. Even considering symptom onset of 1995, this is decades beyond the one-year manifestation period following exposure under 38 C.F.R. § 3.307. Therefore, the presumption under 38 C.F.R. § 3.309 for herbicide agent exposure is not applicable for the Veteran’s upper extremity PN. Service connection may still be awarded on a direct basis. The question for the Board is whether the Veteran’s lower extremity PN was caused by or incurred during service including due to herbicide agent exposure. The Board finds a nexus to service has not been established. The Board finds the September 2016 VA examination and August 2019 VA addendum opinion include consideration of the Veteran’s medical history and set forth all pertinent findings, such that the Board is able to make a fully informed decision. See Stefl, 21 Vet. App. at 123. When considered together and with the entire evidence of record, the Board finds the examination report and addendum adequate for adjudication of the Veteran’s service connection claim because they are based upon an accurate medical history and provide explanations that contain clear conclusions and supporting data. Nieves-Rodriguez, 22 Vet. App. at 304; see also Barr, 21 Vet. App. at 312. With regards to the September 2016 VA addendum opinion, the Board finds this opinion not adequate as it failed to address whether it is at least as likely as not the Veteran’s lower extremity PN was caused by his herbicide agent exposure during service and it fails to provide sufficient rationale as to why it “could be” due to herbicide agent exposure. See Ardison, 6 Vet. App. at 407; see also Nieves-Rodriguez, 22 Vet. App. at 301. Thus, the Board assigns more probative value to the adequate medical opinion and addendum of record. The Veteran’s representative contends that herbicide agent exposure can cause delayed-onset PN. See December 2020 Appellate Brief. In this case, however, the August 2019 VA examiner specifically considered whether the Veteran’s lower extremity PN was caused by herbicide agent exposure. The examiner explained that the Veteran’s PN is idiopathic and attributable to his age which was consistent with his symptom onset. The Board finds this to be highly probative because the examiner specifically considered the Veteran’s symptoms and history in relation to his herbicide agent exposure during service. While the Veteran believes peripheral neuropathy of the lower extremities is caused by herbicide agent exposure, he is not competent to provide a nexus opinion in this case. This issue is medically complex, as it requires specialized medical knowledge. Jandreau v. Nicholson, 492 F.3d 1372, 1377 (Fed. Cir. 2007). Thus, the Board gives more probative weight to the competent medical evidence. Based on the aforementioned, the Board finds the preponderance of the evidence is against an award of service connection for PN of the left and right lower extremities. As such, the benefit-of-the-doubt doctrine is not for application and the claim must be denied. 38 U.S.C. § 5107 (b); see also Gilbert v. Derwinski, 1 Vet. App. 49, 57 (1990). 5. Entitlement to service connection for a sleep disability, to include as secondary to a service-connected disability, is denied. The Veteran contends he has a sleep disability that was caused or incurred during service or is secondary to his PN of the bilateral upper and lower extremities. The Board finds service connection is not warranted. Upon entrance, the Veteran declined experiencing trouble sleeping. See May 1966 entrance examination. During service, treatment records lack reference to any symptoms, treatment, or diagnosis related to a sleep disability. At separation, the Veteran declined experiencing trouble sleeping. See July 1968 separation examination. In 1994, the Veteran reported a history of excessive snoring that became more pronounced over the past few years. See July 1994 non-government treatment records. A sleep study was recommended and the time. Id. In 2011, the Veteran reported worsened sleep problems. See November 2011 Statement in Support of Claim. As decided above, service connection for PN of the bilateral upper and lower extremities has not been awarded. Thus, there is no service-connected disability for which service connection for a sleep disability could be granted on a secondary basis. Further, the Veteran’s service treatment records lack diagnosis of a sleep disability. The Veteran declined experiencing trouble sleeping upon entrance and at separation. The Veteran has not contended his sleep disability began during service. In fact, the Veteran’s treatment records lack any reference or reports of interference with sleep until 1994 during which the Veteran reported a long history of snoring. The Veteran initially contended his sleep disability was secondary to tinnitus for which service connection has been denied. See November 2010 Statement in Support of Claim. Then, alternatively, the Veteran contended his PN symptoms caused or aggravated his sleep disability. Because service connection has not been granted for any conditions, service connection on a secondary basis for a sleep disability must be denied. Additionally, the preponderance of the evidence is against an award of service connection on a direct basis. Shereen M. Marcus Veterans Law Judge Board of Veterans’ Appeals Attorney for the Board A.C. Allen, Associate Counsel The Board’s decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.