The Turkish Journal of Pediatrics 2011; 53: 471-476 Case Report

Benign monomelic amyotrophy in a 7-year-old girl withproximal upper limb involvement: case reportznur Yilmaz', ipek Alemdaroglu', Aye Karaduman', Gknur Haliloglu^,Haluk Topaloglu^'Department of Physical Therapy and Rehabilitation, Faculty of Health Sciences, and ^Unit of Pdiatrie Neurology,Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey

SUMMARY: Yilmaz , Alemdaroglu I, Karaduman A, Haliloglu G,Topaloglu H. Benign monomelic amyotrophy in a 7-year-old girl with proximalupper limb involvement: case report. Tlirk J Pediatr 2011; 53: 471-476.Monomelic amyotrophy (MMA) is a benign motor neuron disease characterizedby neurogenic amyotrophy, which usually affects one of the upper or lowerextremities. Progression is slow and symptoms are clinically stable. Symptomsare seen in the second or third decades of life. In this study, we presenta seven-year-old girl who was diagnosed and directed to the PhysiotherapyDepartment at the age of 5 years and had unilateral proximal upper limljinvolvement. Family history of the case was recorded. Neurologic evaluationwas performed. Range of joint motion, muscle shortness and strength, posture,extremity lengths, gait, timed performance, arm function, and motor andmental maturation were assessed. The physiotherapy program was designedprogressively as strengthening and resistive exercises. Motor and mentaldevelopmental milestones were normal. There was no limitation in activeor passive motion of all joints. She had more flexible joints, scapula alata,

, asymmetry between shoulder levels, and weakness on proximal muscles ofthe right upper extremity. In the follow-up assessment at eight months,there was no asymmetry between shoulder levels and scapular symmetrybegan to improve. Female gender and involvement restricted to one proximalupper limb are rare in the literature. This patient demonstrates the positiveeffects of physical therapy with early diagnosis of MMA. The rapid recoveryof muscle weakness shows the importance of strengthening and resistiveexercises applied to specific muscles in the treatment.Key words: monomelic amyotrophy, lower motor neuron, proximal upper limbinvolvement.

Monomelic amyotrophy (MMA) is a benignmotor neuron disease characterized byneurogenic amyotrophy, which usually affectsone of the upper or lower extremities''^.Young males are affected more. There is nosensory, bulbar or pyramidal involvement'"''.The symptoms are seen in the second or thirddecades of life '^'*'^ . Progression is slow andsymptoms are clinically stable^. MMA is mostlyreported from Asia'"*. Although the cause ofthe disease has not been clearly defined yet,the neuropathological studies showed that thelesion is on the anterior horn motor neuroncells of the spinal cord^.The laboratory findings are normal, except forelectrophysiologic studies. In these studies.

reduced compound muscle activation potentialamplitudes (CMAP) and acute and chronicdenervation in the affected muscles are seen'.Distal muscle groups are predominantly affectedin thisMonomelic amyotrophy (MMA) must bedifferentiated from other lower motor neurondiseases. The discriminative feature of thedisease is the involvement of only one of theupper or lower extremities and restriction ofonly lower motor neurons'.In this case report, we present the two-yearfollow-up of a seven-year-old girl with MMAwho had proximal upper limb involvement andwas diagnosed and directed to physiotherapyat the age of 5 years.

4 7 2 Yilmaz , et al The Turkish Journal of Pediatrics July-August 2011

Case ReportThe presented case was born at termafter an uneventful pregnancy. There wasno consanguinity. Early motor and mentaldevelopmental milestones were normal. Therewas a family history of shoulder problems;however, there was no marked history of aneuromuscular disease.At the age of 5 years, the patient started tocomplain of shoulder pain just after physicaleducation classes and dancing in preschool.The family noticed asymmetry in the shouldergirdle. Her functional and motor developmentwas appropriate for her age; however, duringthe physical examination, she had a mildscapular winging on the right side. Otherthan the mentioned muscle groups involved inTable II, she had no facial or proximal muscleinvolvement in the lower extremities.

Except for muscle strength, the neurologicalexamination was normal, with normal deeptendon reflexes and absence of pyramidal tractinvolvement. Electromyography on referral wasreported to be normal. She was directed tophysiotherapy with the diagnosis of MMA andwas evaluated in the Physiotherapy Departmentat four-month intervals over the followingtwo years.

P h y s i o t h e r a p y A s s e s s m e n t s >

Range of motion: There was no limitation inactive or passive motion of all joints. Moreover,she had more flexible joints (Fig. 1).

Figure 1. Hyperelasticity of elbow joints.

Shortness test: There was no shortness insix muscle groups of the upper and lowerextremities (hip flexors, hamstrings, tensorfasciae latae, gastrocsoleus, pectoralis major orminor, lumbar extensor muscles). No muscleshortness developed during the two-yearfollow-up.Posture analysis: There was no additionalfeature, except scapula alata and asymmetrybetween shoulder levels (Figs. 2, 4). In thefollow-up assessment at eight months, therewas no asymmetry between shoulder levels andscapular symmetry had begun to improve. Inthe assessment in May 2009, the appearance ofshoulder levels was symmetrical (Figs. 3, 5).Extremity lengths: It was confirmed that therewas no difference between upper extremitylengths.Gait analysis: There was no abnormal featurein gait analysis.

Table I. Physical Therapy AssessmentsAssessments

Joint limitationMuscleshortnessPosture analysisShoulder asymmetry 'Scapular asymmetry ' '*Scapula alataTimed performance tests (sec)Standing up from prone ;positionStanding up from supinepositionGait analysis

1st evaluationApril 2007

No

No

YesYesYes

1.5 sec

2 sec

Normal

2nd evaluationApril 2008

No

No

NoYesYes

2 sec

2.5 sec

Normal

3rd evaluationMay 2009

No

No

NoNoNo

3 sec

2.5 sec

Normal

Volume 53 Number 4 Benign Monomelic Amyotrophy with Proximal Upper Limb Invokement 4 7 3

Figure 2. Levels of scapula lower angles and shouldersin arms-up position before physiotherapy.

Timed performance tests: Standing up fromprone and supine position was selected fortimed performance tests (Table I).Arm functional test: The patient was requiredto make a eirele with her arms to assess upperextremity funetion. At the first assessment, sheeould not perform this motion symmetrieally;however, improvement was noted after eightmonths. At the end of the first year, symmetriealmotion was observed in both extremities.Muscle strength: The musel strength wasassessed in Lowet's manual musel testing

positions. There was no weakness in the lowerextremities or the distal musels of the upperextremities (pronators, supinators of the elbow,flexors and extensors of the wrist). The muselstrengths of the upper extremities and trunkare given in Table II.

Physical Therapy ProgramAn exereise program was planned to strengthenthe trunk and proximal upper extremity musclesand to inerease the active upper extremity rangeof motion. This active program was instructedto the family by converting to daily activitiesand games. The family was edueated as to howto apply this program effeetively by eonsideringthe age and motivation of the ehild. Swimmingwas advised. After the first assessment, withinthe first month, the patient started to swimtwo days per week.The physiotherapy program was improvedparallel to ehanges in the patient's eliniealstatus. After the April 2008 assessment,the instrueted aetivities were eonverted to aresisting form by using balls of different sizesand weights. On the other hand, age-relatedarrangements were performed using differentgames in therapy.In the Deeember 2008 assessment, the patientwas instrueted to use a yellow Thera-bandfor strengthening upper extremity musclesbilaterally. The family reported that the patient'senduranee was improved after one year oftherapy; swimming distanee was espeeiallyinereased.

Table II. Musel Strength of the Upper Extremities

Musels

M. rectus ab(dominisBack extensorsM. serratus anteriorUpper part of M. trapeziusMiddle part of M. trapeziusLower part of M. trapeziusAnterior part of M. deltoideusMiddle part of M. deltoi(JeusPosterior part of M. deltoideusM. biceps brachiiM. triceps braehii

R

453

4 '43 +55

1st assessmentApril 2007

L3-t-4

453-1-344455

2nd assessmentApril 2008

R45

555455555

L

555455555

3rd assessmentMay 2009

R45

55 "

555 5 ..'

5 . :.

5 . .,5

L

555555555

4 7 4 Yilmaz , et al The Turkish Journal of Pediatrics July-August 2011

Figure 3. Levels of scapula lower angles and shouldersin arms-up position after 1 year of physiotherapy.

The patient's right upper extremity becameas functional as the left after physiotherapy,and she participates in sportive and dancingactivities at school.

DiscussionMonomelic amyotrophy (MMA) is a rarecondition, which may present a diagnosticchallenge, and it affects especially one limb ofthe upper or lower extremities. There is usuallyunilateral, asymmetric motor neuropathy.Patients with upper or lower limb syndromeshave been reported. This is usually a sporadiccondition, with familial cases with focal upperlimb involvement. The initial progressivecourse is followed by a period of stability.Individual nerves or nerve roots may beaffected, leading to multiple mononeuropathy.Differential diagnosis, especially in adulthood,includes lymphoma, granuloma (sarcoidosis),inflammatory demyelination when thenerve roots are affected, and mechanicalinjury, entrapment, inherited pressure palsy,inflammatory demyelination, tumor, granuloma,and ischmie injury when individual nerves areaffeeted. In the ehildhood period, inflammation,wild-type poliovirus myelitis, polio-like virusmyelitis, and vaeeine-assoeiated paralytiepoliomyelitis have all been diseussed underthe etiologieal elassifieation. Ineidenee andprevalenee of the disease are not reported; itis very uneommon in European populations,and most eases deseribed in the literature arefrom Japan and

Figure 4. Levels of scapula lower angles ancin arms-down position before

physiotherapy.

bhuiders

insidious onset of focal weakness and wasting ofone limb, either arm or leg, of neurogenic cause,b) a history of progression over a period of atleast three years without clinical involvementof any other limb or bodily region, c) puremotor features without sensory symptoms orsigns, d) no evidence of generalized neuropathy,multifocal motor neuropathy or eompressiveneuropathy, according to clinical criteria andnerve conduction studies, e) exclusion ofcausative local pathology and cord compressionby magnetic resonance imaging (MRI), f) noadditional neurological signs, and absence ofcranial nerve or respiratory involvement, g)no potential causative disease such as trauma,cancer, radiation therapy, diabetes, vasculitis,and remote poliomyelitis, h) no family historyof a neuromuscular disorder, i) no signs ofcorticospinal involvement at presentation, andj) normal motor and sensory nerve conductionvelocity and absence of conduction block inall four limbs.

Diagnosis of MMA is based on: a) painless and When we review the characteristics of the

Volume 53 ' Number 4 Benign Monomelic Amyotrophy with Proximal Upper Limb Involcement 4 7 5

Figure 5. Levels of scapula lower angles and shouldersin arm-down position after 1 year

of physiotherapy.

reported patients, it is also known that malesare mostly affected between 26-42 or 15-25years of age^. Ereitas and Nascimento' studied21 cases with benign MMA and found nofamilial cases. About 90% of tbe patientsdeveloped the disease symptoms betweenthe ages of 18-22 years in their study. Theyoungest patient was 4 years old and theoldest was 41 years. Eew cases have beendescribed in the first decade of life and fewfemale cases are reported. Although Ereitas etal.^ reported no male predominance in theirseries, Gourie-Devi et al.^ reported 13 caseswith upper limb involvement and 10 withlower limb involvement, and only 2 patientswere female. Sobue et al.''* reported femalegender in 12 of 71 cases.

Our patient is interesting with respect to boththe female gender and involvement of one upperlimb at the time of presentation. Other thanthe affected muscles in the upper extremity,her neurological examination was normal.

Electromyography performed at referral wasnormal, which may be because of subdinicalinvolvement or pitfalls in the evaluation ofdiagnostic electrophysiological studies inchildren. Subdinical motor involvement inpatients can be demonstrated with centralmotor conduction time (CMCT), especiallyduring voluntary contractions from affected andunaffected limbs'^ Multichannel somatosensoryevoked potentials may also help to demonstratesegmentai cervical cord involvement'^. Thesetwo advanced electrophysiological studieswere not available in our patient. Because ofthe rather benign course and distribution ofmuscle groups involved, cervical MRI studywas not done at the time of presentation inour patient; however, it should be included inthe laboratory work-up to exclude spinal cordpathology in patients with signs of cervicalcord compression.In many of the studies, it has been reportedthat the involvement of the upper extremitiesis usually restricted to the distal parts of theextremities and that deep tendon refiexes areabsent '^^ '^^ ^. The proximal involvement of ourpatient was restricted to the shoulder girdle,and deep tendon refiexes were preserved. Thesevariations in clinical presentations should beconsidered in the diagnosis of MMA.No familial patient has been presented todate; however, our patient's father, the father'ssister and the paternal grandmother had frozenshoulder in their medical history. This historyof shoulder problems in the family must beconsidered in the development of the child andin physiotherapy follow-ups to differentiate thepossible problems that may be caused by MMAand other orthopedic problems in the future.The disease has a special prognosis and thecourse is slowly progressive over one or twoyears but then stable afi:erwards'^. In a differentlong-term study conducted by Peiris et al.'O,it was shown that the disease ceased withinfive years in 75% of patients. Our patient wasfollowed by our unit for two years after thediagnosis. It is different from the cases declaredin the literature previously in that tbe weaknesswas not progressive during the physiotherapyfollow-ups. Conversely, most of the upperlimb muscles strengthened, and symmetricalposture was achieved within one year of thefollow-up and was maintained afterwards. This

4 7 6 Ymaz , et al The Turkish Journal of Pediatrics July-August 2011

may highlight the importance of this dynamicand operational physiotherapy approach. Earlydiagnosis and appropriate physiotherapy mayhave a positive effect in the prognosis of thepatients with MMA. Regular follow-ups byphysiotherapy and pdiatrie neurology areimportant to maintain the medical and physicalimprovement and stabilization.In conclusion, among the patients with an earlydiagnosis of MMA, female gender, involvementrestricted to one proximal upper limb, andstability in the prognosis of the disease arerare presentations. In this case report, a seven-year-old girl who was diagnosed at the age of5 years with proximal upper limb involvementis presented. The positive effects of dynamicphysical therapy in this case with MMA wereshown in this report. The rapid recovery ofmuscle weakness and then a stable phaseof disease demonstrate the importance ofstrengthening and resistive exercises applied tospecific muscles involved in the rehabilitationprocess as well as the family's cooperation.

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