AANEM Case Study: Hirayama s Disease. Children s National Health System George Washington University

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1 AANEM Case Study: Hirayama s Disease Author Information Full Name: Luca Bartolini, MD and Perry K. ichardson, MD Affiliation: Children s National Health System George Washington University No one involved in the planning of this CME activity had any relevant financial relationships to disclose. Authors/Faculty had nothing to disclose. eviewed and accepted by the Website CME Committee of the American Association of Neuromuscular & Electrodiagnostic Medicine Certified for CME credit 10/ /2018 Copyright October 2015 AMEICAN ASSOCIATION OF NEUOMUSCULA & ELECTODIAGNOSTIC MEDICINE ELECTODIOGNOSTIC MEDICINE 2621 Su perior Drive NW ocheste r, MN Case Study: Hirayama s Disease - pg. 1

2 Hirayama s Disease EDUCATIONAL OBJECTIVES: Upon completion of this case study, participants will acquire skills to 1) Compare different causes of chronic unilateral muscle weakness; 2) Define the necessary diagnostic workup in cases of chronic unilateral muscle weakness; and 3) apply electrophysiologic data to formulate the right diagnosis in chronic unilateral muscle weakness. ACCEDITATION STATEMENT: The American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education (CME) for physicians. The AANEM certifies that this CME activity was planned and produced in accordance with ACCME Policies, Accreditation Criteria, and Standards for Commercial Support. CME CEDIT: The AANEM designates this enduring material for a maximum of 2 AMA PA Category 1 Credit(s) TM. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Case Studies published by the AANEM are reviewed every 3 years by an AANEM education committee for their scientific relevance. CME credit is granted for 3 years from the date of publish, review, or revision. Individuals requesting credit for CME materials that have been discontinued will be notified that CME credit is no longer available. CLAIMING CME/CEU CEDIT: The reader should carefully and thoroughly study the material. If further clarification is needed, references should be consulted. To obtain CME/CEU credit: 1. After checkout, a CME survey link will be ed to you from education@aanem.org 2. eview the case study, then follow the CME survey link to complete the post-test 3. After completing the post-test, your CME/CEU transcript will update automatically Case Study: Hirayama s Disease - pg. 2

3 EMG CASE: Hirayama s Disease Luca Bartolini, MD and Perry K. ichardson, MD Presenting Symptom(s): Case-specific Diagnosis: Appropriate Audience: Level of Difficulty: Case Information Chronic weakness of one hand Hirayama s disease esidents, fellows, and practicing physicians Advanced 1. HISTOY A 42-year-old, right-handed Spanish woman presents for evaluation of chronic weakness and muscle wasting of the right hand. Symptoms started 5 years prior to presentation and initially consisted of aching pain of the right hand, which progressively became weak to the point that the patient had to give up painting. More recently, she also noticed hand muscle wasting. 2. COMMENTAY I Based on the history, the differential diagnosis includes: A. Ulnar neuropathy: This is possible, given the muscle atrophy of the intrinsic hand muscles, associated with a weak grip. Usually, ulnar neuropathy is accompanied by sensory changes such as numbness, tingling, or burning in the ring and little fingers and sometimes the medial side of the middle finger. Pain may be present and usually described in the arm and elbow. B. Amyotrophic lateral sclerosis (ALS): Onset of ALS may be characterized by gradual, slowly progressive, painless weakness with no associated sensory changes. As ALS progresses, muscle atrophy and spasticity may affect manual dexterity. Up to 25% of patients may have bulbar involvement. According to the World Federation of Neurology, if only one body region is involved, as in this case, in order to establish a diagnosis of clinically possible ALS both upper motor neuron and lower motor neuron signs are needed. Moreover, median survival is usually 3 years from the onset of weakness. Family Case Study: Hirayama s Disease - pg. 3

4 history is important because of possible mendelian inheritance and strong association with frontotemporal dementia in second- and third-degree relatives. C. Multifocal motor neuropathy with conduction block (MMN): Usually, MMN is characterized by gradual, progressive, painless focal or asymmetric weakness with no sensory loss, often in a distal distribution. It starts in the distribution of individual nerves and it may be associated with muscle atrophy and fasciculations. There are no upper motor neuron signs. The weakness is slowly progressive over up to 30 years. Electrodiagnostic studies show motor conduction block in sites other than those observed in cases of compressive neuropathies. D. Syringomyelia: A cervical syrinx can cause diffuse muscle atrophy and may begin in the hands and progress proximally. The clinical course of syringomyelia may extend over years. However, the syrinx is associated with sensory changes as it interrupts the decussating spinothalamic tract resulting in loss of temperature and pain, while vibration, light touch, and position senses are preserved (dissociated sensory loss). If the syrinx is large enough to involve the posterior columns, then vibration and position senses are lost too. E. Compressive cervical radiculopathy: Typical presentation of compressive cervical radiculopathy comprises neck and arm pain of insidious onset and varying intensity. Pain may be referred to the shoulder and later on radiate to the upper or lower arm and into the hand, in the distribution of the affected nerve root. F. Hirayama s disease: This disease is characterized by an oblique asymmetric muscular atrophy involving C7-T1 myotomes. Hirayama s disease s onset is insidious and often presents in young men from India or Asia. Progression is very gradual over the course of up to 5 years and leads to weakness and atrophy of intrinsic muscles of the hand and forearm with preserved brachioradialis. A similar but even slower progression over decades is observed in the O Sullivan McLeod syndrome. G. Hereditary motor neuropathy (HMN) type 5 (distal spinal muscular atrophy): HMN type 5A is characterized by progressive weakness of the hands with involvement of the thenar eminence and first dorsal interosseous. The mean age of clinical expression is 17 years. Involvement of the lower extremities may be seen in up to 50% of patients after 2 years. HMN type 5C is associated with early weakness of the hands in the same distribution of type 5A but usually asymmetric. Lower extremity involvement is common and foot deformities are observed in up to 95% of patients. The mean age of onset is 15 years. H. Thoracic outlet syndrome (TOS): Lower trunk brachial plexopathy is caused by compression of the neurovascular structures as they pass through the thoracic outlet. TOS usually is characterized by positional numbness along the medial arm. At this point, it is very important to inquire about sensory changes, pain, and any family history of neuromuscular disease, in order to narrow down the differential further. 3. HISTOY, CONTINUED The patient has no sensory changes. She has had some aching pain in her hand for the past 3-5 years. Family history is noncontributory. Laboratory studies reveal positive anti-gm1 Case Study: Hirayama s Disease - pg. 4

5 ganglioside immunoglobulin (Ig) M antibodies (>1:100) with negative IgG, mildly elevated aldolase (10 U/L, reference range ), and normal creatine kinase. 3. COMMENTAY II The relatively indolent course of the patient s symptoms without involvement of other body regions makes the diagnosis of ALS unlikely. The absence of sensory changes makes TOS, ulnar neuropathy, and syringomyelia less likely, although still possible. The age of onset and the lack of family history make HMN type 5 less likely. 4. PHYSICAL EXAMINATION Physical examination shows wasting and weakness of the right first dorsal interosseous (FDI) with a 2/5 Medical esearch Council grading and the right abductor digiti minimi (ADM) with a 2/5. The abductor pollicis brevis (APB), flexor pollicis longus (FPL), flexor digitorum profundus (FDP), and all other muscle groups are all 5/5 with normal bulk. Sensation to all modalities is intact. Deep tendon reflexes are 2+ and symmetrical. 5. COMMENTAY III Based on the physical examination, the main differential diagnosis at this point is a focal motor neuron disorder or MMN. The distribution of weakness in the case presented here is myotomal (C8-T1) and does not involve individual nerves, as is commonly seen in MMN. Case Study: Hirayama s Disease - pg. 5

6 6. ELECTOPHYSIOLOGIC DATA SENSOY NEVE CONDUCTION STUDIES NEVE SIDE STIM SITE ECOD cm AMPL LAT CV Dorsal cutaneous anti sensory ight Wrist Dorsum 5 th metacarpal Lateral ight Lateral Lateral antebrachial biceps forearm cutaneous anti sensory Medial ight Elbow Medial antebrachial forearm cutaneous anti sensory Median anti ight Wrist Index sensory finger Ulnar anti sensory Left Wrist Little finger Ulnar anti sensory ight Wrist Little finger MOTO NEVE CONDUCTION STUDIES NEVE SIDE STIM SITE ECOD cm AMPL LAT CV Median motor ight Wrist APB Median motor ight Elbow APB NA NA Ulnar motor ight Wrist ADM Ulnar motor ight Below ADM elbow Ulnar motor ight Above ADM NA NA elbow Ulnar motor ight Wrist FDI NA Ulnar motor ight Below FDI elbow Ulnar motor ight Above elbow FDI MGA APB = abductor pollicis brevis; NA = not available; ADM = abductor digiti minimi; FDI = first dorsal interosseous; MGA = Martin-Gruber anastomosis Case Study: Hirayama s Disease - pg. 6

7 NEEDLE ELECTOMYOGAPHY INSEtional activity: N, sust, unsust FIB: 0, 1+, 2+, 3+, 4+ OTHer: 0 or fascic, myotonia, myokymia EFFort: N, decr ECruitment: N, inc or dec 1+, 2+, 3+, 4+ AMPlitude: N, inc or dec 1+, 2+, 3+, 4+ DUation: N, inc or dec 1+, 2+, 3+, 4+ POLyphasia: N, inc or dec 1+, 2+, 3+, 4+ /L Muscle Nerve oot INSE FIB/PSW FASC Activation EC AMP DU POL Abductor pollicis brevis Median C8-T1 N 0 0 N *S *+1 *+1 *1+ Abductor digiti minimi Ulnar C8-T1 *Inc *2+ 0 N *MK *+2 *+2 N First dorsal interosseous Flexor digitorum profundus Ulnar C8-T1 *Inc *2+ 0 N *MK *+2 *+2 *1+ Ulnar C8, T1 *Inc *1+ 0 N *S *+1 *+1 *1+ Pronator teres Median C6-7 N 0 0 N N N N N Biceps brachii Musculo- cutaneous C5-6 N 0 0 N N N N N Triceps adial C6-7-8 N 0 0 *Tremulous N N N N Deltoid Axillary C5-6 N 0 0 N N N N N Flexor pollicis Median longus (anterior interosseous) Extensor indicis adial (posterior interosseous) C7-8 N 0 0 N *S *+2 *+2 N C7-8 *Sl Inc 0 0 N *MK *+2 *+2 N MK = markedly reduced, S = slightly reduced 7. DIAGNOSTIC IMPESSION The final diagnosis for the patient is Hirayama s disease. Of note, the patient does not present tremor or minipolymyoclonus on finger extension, as initially described by Hirayama, and her prolonged course raises the possibility of the O Sullivan McLeod syndrome. Case Study: Hirayama s Disease - pg. 7

8 8. COMMENTAY IV Nerve conduction studies showed normal sensory nerve action potentials. Also, there was no evidence of conduction block. Incidentally noted was evidence of a Martin Gruber anastomosis to the FDI, a normal anatomic variant. Needle electromyography showed severe acute and chronic changes consistent with acute and chronic C8 radiculopathy or focal motor neuron disease, with a partial dissociation of median (APB) and ulnar (FDI, ADM) nerves. A magnetic resonance imaging (MI) of the C-spine was normal. Given the gradual progression of a focal purely motor syndrome with no imaging abnormalities, the patient was diagnosed with Hirayama s disease, or possible O Sullivan McLeod syndrome. Hirayama s disease (benign monomelic amyotrophy) is a rare oblique asymmetric muscular atrophy involving C7-T1 myotomes. Its onset is insidious, and it usually presents in young men from India or Asia. Progression is very gradual over the course of up to 5 years and leads to weakness and atrophy of intrinsic muscles of the hand and forearm with preserved brachioradialis. A more prolonged course comprises a rare variant, the O Sullivan McLeod syndrome. The etiology is poorly understood, but it may be related to laxity of the cervical thecal sac, with motor neuron damage with neck flexion and extension. Dynamic spinal MI of the neck can reveal intramedullary T2 hyperintensity, representing atrophy and gliosis of the anterior horn cells. Anterior cervical fusion or the use of a cervical collar have been described as possible treatment for Hirayama s disease, but the evidence remains anecdotal. This patient is of particular interest for several reasons. The majority of cases of Hirayama s disease are young men from India or Asia; this patient is a middle-aged woman from Spain. Moreover, she did not present tremor or minipolymyoclonus on finger extension, as initially described by Hirayama, and her prolonged course raises the possibility of the O Sullivan McLeod syndrome. The measurement of anti-gm1 ganglioside antibodies can be helpful in cases of motor predominant neuropathies with minimal sensory involvement. A titer of less than 1:400 may not be clinically significant. Further cervical MI studies with flexion are pending. 10. BIBLIOGAPHY 1. Autoantibodies in chronic motor syndromes. Neuromuscular Disease Center Website, Washington University, St. Louis, MO ( Accessed August 3, Lehman VT, Luetmer PH, Sorenson EJ, et al. Cervical spine M imaging findings of patients with Hirayama disease in North America: a multisite study. Am J Neuroradiol 2013;34: Patel D, Knepper L, Jones H Jr. Late-onset monomelic amyotrophy in a Caucasian woman. Muscle Nerve 2008;37: Petiot P, Gonon V, Froment JC, Vial C, Vighetto A. Slowly progressive spinal muscular atrophy of the hands (O Sullivan-McLeod syndrome): clinical and magnetic resonance imaging presentation. J Neurol 2000;247: Case Study: Hirayama s Disease - pg. 8

Distal chronic spinal muscular atrophy involving the hands

Journal ofneurology, Neurosurgery, and Psychiatry, 1978, 41, 653-658 Distal chronic spinal muscular atrophy involving the hands D. J. O'SULLIVAN AND J. G. McLEOD From St Vincent's Hospital, and Department