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Transient motor paresis caused by herpes zoster
J Shoulder Elbow Surg (2016) 25, e309–e312
www.elsevier.com/locate/ymse
Transient motor paresis caused by herpes zoster Sang-Eun Park, MD, Prasanth Ganji, MS (Ortho), Jong-Hun Ji, MD*, Seong Hyeon Park, MD Department of Orthopedic Surgery, College of Medicine, The Catholic University of Korea, Daejeon St Mary’s Hospital, Daejeon, Republic of Korea Keywords: Motor weakness; upper trunk; brachial plexus; paresis; herpes zoster infection; rotator cuff tear
Segmental zoster paresis is characterized by focal, asymmetrical motor weakness in the myotome that corresponds to the dermatome of a skin rash. A 73-year-old man and a 76-year-old woman who presented with severe right shoulder pain and weakness were diagnosed with segmental zoster paretic involvement of the upper trunk (C5-C6) of the brachial plexus as a complication of herpes zoster. Magnetic resonance imaging (MRI) showed a large cuff tear in 1 patient and a small cuff tear in the other patient. Despite 2 months of conservative treatment for herpetic neuralgia, the patient with the large rotator cuff tear had persistent shoulder pain, particularly at night, and underwent arthroscopic rotator cuff repair. Conservative treatment was performed for the small rotator cuff tear in the other patient. Both patients showed satisfactory clinical results at the last follow-up. In this study, we present these 2 cases to emphasize that post-herpetic segmental motor paresis should be considered in the differential diagnosis of acute painful motor weakness of the upper extremities, such as brachial neuritis. We report the clinical courses of 2 patients with herpes zoster infection combined with rotator cuff tear.
Case 1 A 73-year-old man presented with right shoulder pain and weakness. Active range of motion was limited to 15° of Because this is a case report, no Institutional Review Board approval was required. *Reprint requests: Jong-Hun Ji, MD, Department of Orthopaedic Surgery, Daejeon St Mary’s Hospital, The Catholic University of Korea, 502-2, Daehung-dong, Joong-ku, Daejeon 302-803, Republic of Korea. E-mail address: [email protected] (J.-H. Ji).
forward flexion and 20° of abduction, and the biceps reflex was absent. Shoulder flexion power was grade 2 of 5, and abduction was grade 2 of 5. The biceps was grade 3 of 5. The muscles distal to the elbow were spared. The patient had no history of trauma. Regarding the patient’s medical history, he reported pain and tingling in the right shoulder 1 week prior and development of a skin rash 3 days after the tingling and pain. He was diagnosed with herpes zoster infection and underwent brachial plexus block for pain relief. On physical examination, the patient had a skin lesion in the C5-C6 dermatomes of the right shoulder and arm (Fig. 1). Vesicles formed on the posterior neck and right shoulder 4 days later. A nerve conduction study (NCS) and needle electromyography (EMG) were performed 3 weeks after the onset of the herpes zoster eruption, and the patient was diagnosed with brachial plexopathy of the upper trunk (C5-C6). Despite 2 months of conservative treatment for herpetic neuralgia, the shoulder pain persisted, particularly at night. Moreover, muscle atrophy around the shoulder joint was observed. Plain radiography showed an acromial spur and inferior subluxation of the humeral head. MRI showed a large, fullthickness rotator cuff tear (Fig. 2). Follow-up EMG and NCS performed 2 months after the onset of the herpes zoster infection showed an increased frequency of polyphasic motor unit action potentials in the infraspinatus, deltoid, and biceps brachii muscles and the reappearance of volitional interference activity, indicating reinnervation. The patient had 80° of forward flexion, 70° of abduction, 10° of external rotation, and internal rotation to the fourth lumbar vertebra. We decided to perform arthroscopic surgery because of persistent weakness and increased pain at night.
1058-2746/$ - see front matter © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. http://dx.doi.org/10.1016/j.jse.2016.07.023
e310
Figure 1 (A) Skin lesions developed along the C5 segment of the right shoulder joint. (B) Atrophy of the supraspinatus and infraspinatus muscles and subluxation of the right shoulder joint.
Arthroscopic surgery The glenohumeral joint was evaluated, and the arthroscope was moved to the subacromial space. The supraspinatus tendon showed a large 4 × 3–cm tear (Fig. 3). A tendon-to-tendon repair was performed using No. 2 Ethibond (Ethicon, Somerville, NJ, USA) to repair the torn cuff margin. A Twinfix anchor (Smith & Nephew, Andover, MA, USA) was used for the arthroscopic double-row repair.
Postoperative course Shoulder pain was almost absent at the final follow-up 3 years later. The American Shoulder and Elbow Surgeons score improved from 15 to 96.5 points, and the University of California, Los Angeles score improved from 6 to 34 points. The patient had 150° of forward flexion, 145° of abduction, 40° of external rotation, and internal rotation to the 12th thoracic vertebra. Muscle strength in the shoulder and elbow had returned to normal.
Case 2 A 76-year-old woman presented with a skin lesion over the C5-C6 dermatome of the right shoulder (Fig. 4). Multiple
Figure 2 Oblique sagittal magnetic resonance image showing a large, full-thickness tear of the supraspinatus tendon (arrow) but intact subscapularis and infraspinatus tendons.
S.-E. Park et al.
Figure 3 Arthroscopic images showing a large-sized tear of the supraspinatus tendon (A) and the repaired tendon (B).
vesicles were observed on the right shoulder and upper arm. She had had a headache in the right temporal area 1 week prior, and 4 days later, vesicles and pain developed on the posterior neck and right shoulder. A herpes zoster infection was diagnosed, and acyclovir was prescribed. She had no history of diabetes mellitus or hypertension. No tenderness was found in the shoulder. The patient had 10° of active flexion, 20° of active abduction, 10° of active external rotation, and internal rotation to the buttocks level. She exhibited motor weakness on shoulder flexion (grade 2 of 5) and abduction (grade 2 of 5). The biceps was checked (grade 3+ of 5). Deep tendon reflexes were diminished in the right biceps. The impingement and drop-arm signs were positive. MRI showed a small (1-cm) full-thickness rotator cuff tear and a type 3 acromion with a spur (Fig. 5). We performed an NCS and needle EMG 3 weeks after the onset of the herpes zoster eruption, and the condition was diagnosed as brachial plexopathy of the upper trunk (C5-C6). We opted for conservative treatment consisting of medications and physiotherapy. The patient’s pain improved, so we continued conservative treatment. Strength had improved to grade 3 to 4 at a 2-month follow-up. Pain had improved but was present at the insertion point of the deltoid. Strength had improved to grade 5 at a 6-month follow-up. At 1 year of followup, the American Shoulder and Elbow Surgeons score was 88 points; the University of California, Los Angeles score was 32 points; and the Simple Shoulder Test score was 10 points. Final range of motion was forward flexion of 150°, abduction of 150°, external rotation of 10°, and internal rotation to L2.
Figure 4 (A, B) Vesicles and severe pain developed on the posterior neck and area under the right shoulder. The patient had 10° of forward flexion and 20° of abduction.
Rotator cuff tears in herpes zoster
e311
Figure 5 (A) Radiograph showing an acromial spur and osteophyte of the greater tuberosity. (B, C) Magnetic resonance images showing a small, full-thickness tear of the anterior supraspinatus tendon (arrows) but intact subscapularis and infraspinatus tendons.
Discussion This study showed that after the development of motor nerve paresis due to herpes zoster, an asymptomatic torn rotator cuff may become a symptomatic tear. Depending on the tear size and the ongoing symptoms of the patients, treatment of the torn cuff should be individualized. In our cases, we performed arthroscopic rotator cuff repair in a patient with a largesized cuff tear and the other patient, with a small-sized cuff tear, recovered well from motor nerve paresis without rotator cuff repair. The incidence of herpes zoster is 10.4 cases per 1000 person-years; there are 12.6 cases per 1000 person-years in women and 8.3 cases per 1000 person-years in men.9 The motor nerves can be invaded along the myotomes during a herpes zoster eruption. Aktas et al2 reported that the longterm prognosis of the paralysis caused by herpes zoster was good in most cases and that herpes zoster–associated axillary neuropathy could mimic subacromial impingement syndrome; therefore, relying on MRI alone might lead to a misdiagnosis. Clinical and electrophysiological evaluations are important in patients with shoulder problems. EMG aids in the accurate evaluation of motor nerve damage caused by herpes zoster infection,1,10 and it is a very sensitive measure of motor nerve invasion.4,7 In our cases, brachial plexopathy of the upper trunk was diagnosed by EMG. Skin rash over the C5 and C6 dermatomes and motor weakness in the shoulder and elbow were noted. Segmental paresis caused by herpes zoster eruption has been reported 2 to 3 weeks after the beginning of the eruption.10 After herpes zoster paresis, complete or almost complete recovery of muscle function occurs in more than 50% of patients within 6 to 12 months.8 However, permanent paralysis of the motor nerves in the myotome of the trunk, the unilateral diaphragm, and the anterior area of the tibia has been reported.6 Geertzen et al5 showed that patients with brachial plexus neuropathy may have significant disability. Neither of our patients had shoulder pain or discomfort before the zoster-induced paresis. However, both patients had herpes zoster infection involving the upper trunk of the brachial plexus combined with rotator cuff tears, making it very difficult to pinpoint the exact cause of the shoulder pain. We performed 2 months’ conservative treatment during the motor
nerve recovery period in both patients. However, in the patient with the large rotator cuff tear, conservative treatment for 2 months failed and shoulder pain was aggravated. On the other hand, the patient with the small rotator cuff tear showed improvements of shoulder pain and motor weakness following conservative treatment. Large-sized full-thickness rotator cuff tears involving the supraspinatus and infraspinatus muscles may disrupt the normal balance of force, resulting in loss of a stable fulcrum and abnormal loading. Burkhart3 reported that if transverse force coupling remains functional, the balanced motor mechanism of the shoulder joint will maintain a properly centered humeral head. In our series, we assumed that the asymptomatic rotator cuff tear became symptomatic owing to altered balanced force coupling caused by zoster paresis in our patient with the large rotator cuff tear. The pattern of pain may change from neuropathic pain caused by herpes zoster to somatic pain caused by the rotator cuff tear. However, the patient with the small rotator cuff tear was asymptomatic after zoster paresis because there was less of a change in balanced force coupling of the rotator cuff muscles.
Conclusion Any change in the pattern of pain should be a focus during treatment of a herpes zoster eruption in elderly patients with rotator cuff tears, particularly if shoulder pain was absent before herpes zoster infection.
Disclaimer The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
References 1. Akiyama N. Herpes zoster infection complicated by motor paralysis. J Dermatol 2000;27:252-7. 2. Aktas I, Akgun K, Gunduz OH. Axillary mononeuropathy after herpes zoster infection mimicking subacromial impingement syndrome. Am
e312
3.
4.
5.
6.
J Phys Med Rehabil 2008;87:859-61. http://dx.doi.org/10.1097/ PHM.0b013e318186bb95 Burkhart SS. Reconciling the paradox of rotator cuff repair versus debridement: a unified biomechanical rationale for the treatment of rotator cuff tears. Arthroscopy 1994;10:4-19. Cioni R, Giannini F, Passero S, Paradiso C, Rossi S, Fimiani M, et al. An electromyographic evaluation of motor complications in thoracic herpes zoster. Electromyogr Clin Neurophysiol 1994;34:125-8. Geertzen JH, Groothoff JW, Nicolai JP, Rietman JS. Brachial plexus neuropathy. A long-term outcome study. J Hand Surg Br 2000;25:461-4. Gerber C. Massive rotator cuff tears. In: Iannotti JP, Gerald R, Williams J, Miniaci A, Zuckerman JD, editors. Disorders of the shoulder: diagnosis
S.-E. Park et al.
7. 8. 9.
10.
and management. Philadelphia: Lippincott Williams & Wilkins; 1999. p. 57-92. Greenberg MK, McVey AL, Hayes T. Segmental motor involvement in herpes zoster: an EMG study. Neurology 1992;42:1122-3. Gupta SK, Helal BH, Kiely P. The prognosis in zoster paralysis. J Bone Joint Surg Br 1969;51:593-603. Kim YJ, Lee CN, Lim CY, Jeon WS, Park YM. Population-based study of the epidemiology of herpes zoster in Korea. J Korean Med Sci 2014;29:1706-10. http://dx.doi.org/10.3346/jkms.2014.29.12.1706 Mondelli M, Romano C, Della Porta P, Rossi A. Electrophysiological findings in peripheral fibres of subjects with and without postherpetic neuralgia. Electroencephalogr Clin Neurophysiol 1996;101: 185-91.
www.elsevier.com/locate/ymse
Transient motor paresis caused by herpes zoster Sang-Eun Park, MD, Prasanth Ganji, MS (Ortho), Jong-Hun Ji, MD*, Seong Hyeon Park, MD Department of Orthopedic Surgery, College of Medicine, The Catholic University of Korea, Daejeon St Mary’s Hospital, Daejeon, Republic of Korea Keywords: Motor weakness; upper trunk; brachial plexus; paresis; herpes zoster infection; rotator cuff tear
Segmental zoster paresis is characterized by focal, asymmetrical motor weakness in the myotome that corresponds to the dermatome of a skin rash. A 73-year-old man and a 76-year-old woman who presented with severe right shoulder pain and weakness were diagnosed with segmental zoster paretic involvement of the upper trunk (C5-C6) of the brachial plexus as a complication of herpes zoster. Magnetic resonance imaging (MRI) showed a large cuff tear in 1 patient and a small cuff tear in the other patient. Despite 2 months of conservative treatment for herpetic neuralgia, the patient with the large rotator cuff tear had persistent shoulder pain, particularly at night, and underwent arthroscopic rotator cuff repair. Conservative treatment was performed for the small rotator cuff tear in the other patient. Both patients showed satisfactory clinical results at the last follow-up. In this study, we present these 2 cases to emphasize that post-herpetic segmental motor paresis should be considered in the differential diagnosis of acute painful motor weakness of the upper extremities, such as brachial neuritis. We report the clinical courses of 2 patients with herpes zoster infection combined with rotator cuff tear.
Case 1 A 73-year-old man presented with right shoulder pain and weakness. Active range of motion was limited to 15° of Because this is a case report, no Institutional Review Board approval was required. *Reprint requests: Jong-Hun Ji, MD, Department of Orthopaedic Surgery, Daejeon St Mary’s Hospital, The Catholic University of Korea, 502-2, Daehung-dong, Joong-ku, Daejeon 302-803, Republic of Korea. E-mail address: [email protected] (J.-H. Ji).
forward flexion and 20° of abduction, and the biceps reflex was absent. Shoulder flexion power was grade 2 of 5, and abduction was grade 2 of 5. The biceps was grade 3 of 5. The muscles distal to the elbow were spared. The patient had no history of trauma. Regarding the patient’s medical history, he reported pain and tingling in the right shoulder 1 week prior and development of a skin rash 3 days after the tingling and pain. He was diagnosed with herpes zoster infection and underwent brachial plexus block for pain relief. On physical examination, the patient had a skin lesion in the C5-C6 dermatomes of the right shoulder and arm (Fig. 1). Vesicles formed on the posterior neck and right shoulder 4 days later. A nerve conduction study (NCS) and needle electromyography (EMG) were performed 3 weeks after the onset of the herpes zoster eruption, and the patient was diagnosed with brachial plexopathy of the upper trunk (C5-C6). Despite 2 months of conservative treatment for herpetic neuralgia, the shoulder pain persisted, particularly at night. Moreover, muscle atrophy around the shoulder joint was observed. Plain radiography showed an acromial spur and inferior subluxation of the humeral head. MRI showed a large, fullthickness rotator cuff tear (Fig. 2). Follow-up EMG and NCS performed 2 months after the onset of the herpes zoster infection showed an increased frequency of polyphasic motor unit action potentials in the infraspinatus, deltoid, and biceps brachii muscles and the reappearance of volitional interference activity, indicating reinnervation. The patient had 80° of forward flexion, 70° of abduction, 10° of external rotation, and internal rotation to the fourth lumbar vertebra. We decided to perform arthroscopic surgery because of persistent weakness and increased pain at night.
1058-2746/$ - see front matter © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. http://dx.doi.org/10.1016/j.jse.2016.07.023
e310
Figure 1 (A) Skin lesions developed along the C5 segment of the right shoulder joint. (B) Atrophy of the supraspinatus and infraspinatus muscles and subluxation of the right shoulder joint.
Arthroscopic surgery The glenohumeral joint was evaluated, and the arthroscope was moved to the subacromial space. The supraspinatus tendon showed a large 4 × 3–cm tear (Fig. 3). A tendon-to-tendon repair was performed using No. 2 Ethibond (Ethicon, Somerville, NJ, USA) to repair the torn cuff margin. A Twinfix anchor (Smith & Nephew, Andover, MA, USA) was used for the arthroscopic double-row repair.
Postoperative course Shoulder pain was almost absent at the final follow-up 3 years later. The American Shoulder and Elbow Surgeons score improved from 15 to 96.5 points, and the University of California, Los Angeles score improved from 6 to 34 points. The patient had 150° of forward flexion, 145° of abduction, 40° of external rotation, and internal rotation to the 12th thoracic vertebra. Muscle strength in the shoulder and elbow had returned to normal.
Case 2 A 76-year-old woman presented with a skin lesion over the C5-C6 dermatome of the right shoulder (Fig. 4). Multiple
Figure 2 Oblique sagittal magnetic resonance image showing a large, full-thickness tear of the supraspinatus tendon (arrow) but intact subscapularis and infraspinatus tendons.
S.-E. Park et al.
Figure 3 Arthroscopic images showing a large-sized tear of the supraspinatus tendon (A) and the repaired tendon (B).
vesicles were observed on the right shoulder and upper arm. She had had a headache in the right temporal area 1 week prior, and 4 days later, vesicles and pain developed on the posterior neck and right shoulder. A herpes zoster infection was diagnosed, and acyclovir was prescribed. She had no history of diabetes mellitus or hypertension. No tenderness was found in the shoulder. The patient had 10° of active flexion, 20° of active abduction, 10° of active external rotation, and internal rotation to the buttocks level. She exhibited motor weakness on shoulder flexion (grade 2 of 5) and abduction (grade 2 of 5). The biceps was checked (grade 3+ of 5). Deep tendon reflexes were diminished in the right biceps. The impingement and drop-arm signs were positive. MRI showed a small (1-cm) full-thickness rotator cuff tear and a type 3 acromion with a spur (Fig. 5). We performed an NCS and needle EMG 3 weeks after the onset of the herpes zoster eruption, and the condition was diagnosed as brachial plexopathy of the upper trunk (C5-C6). We opted for conservative treatment consisting of medications and physiotherapy. The patient’s pain improved, so we continued conservative treatment. Strength had improved to grade 3 to 4 at a 2-month follow-up. Pain had improved but was present at the insertion point of the deltoid. Strength had improved to grade 5 at a 6-month follow-up. At 1 year of followup, the American Shoulder and Elbow Surgeons score was 88 points; the University of California, Los Angeles score was 32 points; and the Simple Shoulder Test score was 10 points. Final range of motion was forward flexion of 150°, abduction of 150°, external rotation of 10°, and internal rotation to L2.
Figure 4 (A, B) Vesicles and severe pain developed on the posterior neck and area under the right shoulder. The patient had 10° of forward flexion and 20° of abduction.
Rotator cuff tears in herpes zoster
e311
Figure 5 (A) Radiograph showing an acromial spur and osteophyte of the greater tuberosity. (B, C) Magnetic resonance images showing a small, full-thickness tear of the anterior supraspinatus tendon (arrows) but intact subscapularis and infraspinatus tendons.
Discussion This study showed that after the development of motor nerve paresis due to herpes zoster, an asymptomatic torn rotator cuff may become a symptomatic tear. Depending on the tear size and the ongoing symptoms of the patients, treatment of the torn cuff should be individualized. In our cases, we performed arthroscopic rotator cuff repair in a patient with a largesized cuff tear and the other patient, with a small-sized cuff tear, recovered well from motor nerve paresis without rotator cuff repair. The incidence of herpes zoster is 10.4 cases per 1000 person-years; there are 12.6 cases per 1000 person-years in women and 8.3 cases per 1000 person-years in men.9 The motor nerves can be invaded along the myotomes during a herpes zoster eruption. Aktas et al2 reported that the longterm prognosis of the paralysis caused by herpes zoster was good in most cases and that herpes zoster–associated axillary neuropathy could mimic subacromial impingement syndrome; therefore, relying on MRI alone might lead to a misdiagnosis. Clinical and electrophysiological evaluations are important in patients with shoulder problems. EMG aids in the accurate evaluation of motor nerve damage caused by herpes zoster infection,1,10 and it is a very sensitive measure of motor nerve invasion.4,7 In our cases, brachial plexopathy of the upper trunk was diagnosed by EMG. Skin rash over the C5 and C6 dermatomes and motor weakness in the shoulder and elbow were noted. Segmental paresis caused by herpes zoster eruption has been reported 2 to 3 weeks after the beginning of the eruption.10 After herpes zoster paresis, complete or almost complete recovery of muscle function occurs in more than 50% of patients within 6 to 12 months.8 However, permanent paralysis of the motor nerves in the myotome of the trunk, the unilateral diaphragm, and the anterior area of the tibia has been reported.6 Geertzen et al5 showed that patients with brachial plexus neuropathy may have significant disability. Neither of our patients had shoulder pain or discomfort before the zoster-induced paresis. However, both patients had herpes zoster infection involving the upper trunk of the brachial plexus combined with rotator cuff tears, making it very difficult to pinpoint the exact cause of the shoulder pain. We performed 2 months’ conservative treatment during the motor
nerve recovery period in both patients. However, in the patient with the large rotator cuff tear, conservative treatment for 2 months failed and shoulder pain was aggravated. On the other hand, the patient with the small rotator cuff tear showed improvements of shoulder pain and motor weakness following conservative treatment. Large-sized full-thickness rotator cuff tears involving the supraspinatus and infraspinatus muscles may disrupt the normal balance of force, resulting in loss of a stable fulcrum and abnormal loading. Burkhart3 reported that if transverse force coupling remains functional, the balanced motor mechanism of the shoulder joint will maintain a properly centered humeral head. In our series, we assumed that the asymptomatic rotator cuff tear became symptomatic owing to altered balanced force coupling caused by zoster paresis in our patient with the large rotator cuff tear. The pattern of pain may change from neuropathic pain caused by herpes zoster to somatic pain caused by the rotator cuff tear. However, the patient with the small rotator cuff tear was asymptomatic after zoster paresis because there was less of a change in balanced force coupling of the rotator cuff muscles.
Conclusion Any change in the pattern of pain should be a focus during treatment of a herpes zoster eruption in elderly patients with rotator cuff tears, particularly if shoulder pain was absent before herpes zoster infection.
Disclaimer The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
References 1. Akiyama N. Herpes zoster infection complicated by motor paralysis. J Dermatol 2000;27:252-7. 2. Aktas I, Akgun K, Gunduz OH. Axillary mononeuropathy after herpes zoster infection mimicking subacromial impingement syndrome. Am
e312
3.
4.
5.
6.
J Phys Med Rehabil 2008;87:859-61. http://dx.doi.org/10.1097/ PHM.0b013e318186bb95 Burkhart SS. Reconciling the paradox of rotator cuff repair versus debridement: a unified biomechanical rationale for the treatment of rotator cuff tears. Arthroscopy 1994;10:4-19. Cioni R, Giannini F, Passero S, Paradiso C, Rossi S, Fimiani M, et al. An electromyographic evaluation of motor complications in thoracic herpes zoster. Electromyogr Clin Neurophysiol 1994;34:125-8. Geertzen JH, Groothoff JW, Nicolai JP, Rietman JS. Brachial plexus neuropathy. A long-term outcome study. J Hand Surg Br 2000;25:461-4. Gerber C. Massive rotator cuff tears. In: Iannotti JP, Gerald R, Williams J, Miniaci A, Zuckerman JD, editors. Disorders of the shoulder: diagnosis
S.-E. Park et al.
7. 8. 9.
10.
and management. Philadelphia: Lippincott Williams & Wilkins; 1999. p. 57-92. Greenberg MK, McVey AL, Hayes T. Segmental motor involvement in herpes zoster: an EMG study. Neurology 1992;42:1122-3. Gupta SK, Helal BH, Kiely P. The prognosis in zoster paralysis. J Bone Joint Surg Br 1969;51:593-603. Kim YJ, Lee CN, Lim CY, Jeon WS, Park YM. Population-based study of the epidemiology of herpes zoster in Korea. J Korean Med Sci 2014;29:1706-10. http://dx.doi.org/10.3346/jkms.2014.29.12.1706 Mondelli M, Romano C, Della Porta P, Rossi A. Electrophysiological findings in peripheral fibres of subjects with and without postherpetic neuralgia. Electroencephalogr Clin Neurophysiol 1996;101: 185-91.