ELECTRODIAGNOSIS(EDx) IN: ENTRAPMENT NEUROPATHIES Prepared by: Ali Farkhani M.D Physiatrist(PM&R)

ELECTRODIAGNOSIS ROLE IN ENTRAPMENT NEUROPATHIES: 1- Confirming the site of lesion 2-Estimating severity of injury 3-Judge the pathophysiologic nature 4-Prognostication

Classification of peripheral nervous lesions: Suderland 1th degree 2th degree 3th degree 4 th degree 5 th degree SeddonNeuraraxiaAxonotmesisNeurotmesis EDx Conduction block Axon loss Pathology Demyelinati on` Intact supporting Disrupted endoneureu m Disrupted endo and perineurium All supporting structures Prognosis 2-3 mos excellent recovery Slow rec Protracted unlikely without surgery Imossible without surgery

Major EDx consequencies:. Focal slowing.Conduction block.Axon loss(Wallerian degeneration)

EDx criteria for Conduction block : Definite in any nerve: >50% decrease in CMAP Amp with <15% prolongation of Dur >50% decrease in CMAP Area >30% decrease in Area or Amp over a short nerve segment Possible in only median,ulnar and peroneal n: 20%-50% in CMAP Amp,with<15% prolongation of Dur 20%-50% decrease in CMAP Area

Axon loss(Wallerian degeneration) Completed within 7-11 days EDx abnormalities appear: Distal CMAP: 5-6 days Distal SNAP: days Fibrillation and PSWs: days

Common Enrapment Neuropathies CRANIAL NERVES:  Facial n  Accessory n  Scapular winging(inf angle: inward,whole scapula slips downward,worsens by Abd  SCM atrophy and Fib

Common Enrapment Neuropathies UPPER EXTREMITIE(UE ): 1-Median n: 1-Median n: Pronator teres(P.T) Sx Pronator teres(P.T) Sx Entrapment at ligamentum of Struthers Entrapment at ligamentum of Struthers Anterior interosseous nerve Sx Anterior interosseous nerve Sx Carpal tunnel Sx Carpal tunnel Sx Digital nerve entrapment Digital nerve entrapment Radial n: Radial n: Entrapment at spiral groove Entrapment at spiral groove Posterior interosseous syndrom Posterior interosseous syndrom Ulnar n: Ulnar n: Tardy uln palsy and cubital tunnel Sx Tardy uln palsy and cubital tunnel Sx Compression at Guyon’s canal Compression at Guyon’s canal Involvement of palmar branch Involvement of palmar branch

Shoulder Girdle nerve entrapments:  Long thoracic n  Scapular winging(DDx with accessory n lesion)  Hx of heavy shoulder bag or shoulder braces,radical mastectomy  Suprascapular n  In volleyball serving,RCT,crutches  Dorsal scapular n  Winging of scapula at wide Abd  EMG Abn restricted o rhomboids and levator scapula  Axillary n  Hyperextention in wrestling,cruthes,Fx or Dx of head of humerus  Limited Abd after 30 degrees  Musculocutaneous n

Entrapment n s of Lower Extremities(LE):  Pelvic Girdle Sciatic n Fem n Lat Fem Cut n(LFCN) Saphenous n Obturator n  Common Peroneal n(CPN)  Tibial n T.T.S Sural n

EDx in individual nerve entrapments: Median n(C.T.S) Causes:  Idiopathic  Secondary(pregnancy,DM,R.A,acromegaly hyperthyroidism,hyperpar athyroidism, tenosynovitis,Colle’s Fx)

EDx in C.T.S:  Nerve Conduction Studies(NCS): Delayed S or M Lat(1/2-2/3 Pts) Delayed Compound nerve AP(less dilution) Comparison of median S Lat to ulnar or radial Inching techniqu of Kimura( ms/cm)  Needle EMG: Thenar m(fib or PSW indicates ongoing denervation) Excluding other causes of hand numbness(cervical radiculopathy,T.O.S)

Ulnar neuropathy at Cubital tunnel Sx, Anatomy:

Ulnar neuropathy : Cubital tunnel Sx No Hx of trauma,Def or arthritis Proposed lesion(FCU aponeurosis) EDx: sensory NCS(dorsal ulnar SNAP,palmar 5 th digit SNAP),motor NCS Evalute for:Slowing,Conductiobn Block or Axon Loss  How much slowing? Long segment comparison:>10 m/s Short segment comparison:>15 m/s  EMG: FCU & FDP Usually spared in lesions around elbow(>50% Pts)

Ulnar n at Guyon’s canal: Anatomy:

Ulnar n at Guyon’s canal: Common causes:  Ganglion  Compression at pisohamate hiatus: Occupational or recreational(e.g: use of hand tools,bicycling) With acute closed injuries(e.g: fall on hand,carpal Fx) Idiopathic Other space occupying lesions(neuroma,lipoma,cyst,false aneurism,giant cell tumor)

Distal ulnar entrapments: Proximal Guyon’s canal Palmar S loss and weakness of all intrinsics Distal Guyon’s canal: No S loss,weakness of all intrinsic m Pisohamate hiatus Sparing of hypothenar m,No S loss Mid palm Sparing the 4 th interossei and hypothenar m,No S loss

Radial n neuropathies: Acute compression at spiral groove –Saturday night palsy,Honeymoon palsy,Intraoperative,Coma Humeral Fx Sternous muscle effort Injection injury Open trauma

EDx in Radial mononeuropathies:  Establish lesion of main trunk: Motor Block across spiral groove Decrease SNAP Amp(Dist)  Finding exact location: Denervation in Brachioradialis and/or ECRL,ECRB Normal Triceps(and Anconeous) Normal Deltoid  Prognosticate CMAP Amp & Area In lesions of combined pathophysiology is biphasic

DDx of common causes of wrist drop/finger drop:

Sciatic neuropathy: Common causes(descending order of frequency) Hip replacement,Fx or Dx,femor Fx Acute compression(coma,drug overdose,ICU,prolonged sitting) Gunshot or knife wounds Infarction(vasculitis…) Gluteal contusionor compartment syndrom(during anticoagulation) Gluteal injection Endometriosis(catamenial sciatica)

Peroneal neuropathy at fibular head Common causes  Recent anesthesia and surgery  Wheight loss  Recent prolonged hospitalization)including bedrest and coma)  Habitual leg crossing  Diabetes  Others(prolonged squatting,braces,plaster casts)

Peroneal neuropathy at fibular head

Tarsal Tunnel Syndrom(TTS): Burning pain over sole of the foot,sens deficit in the toes and sole,weakness of intrinsic m Burning pain over sole of the foot,sens deficit in the toes and sole,weakness of intrinsic m Often with Hx of Fx,Dx or sprain Often with Hx of Fx,Dx or sprain EDx: EDx: Difference in motor lat(med or lat plantar n) >1 ms Difference in motor lat(med or lat plantar n) >1 ms CMAP onset lat(not sensitive) CMAP onset lat(not sensitive) >4.8 : medial plantar >4.8 : medial plantar >4.9 : lat plantar >4.9 : lat plantar CNAP lat > 3.8 ms(14 cm dist) CNAP lat > 3.8 ms(14 cm dist) EMG:?/AH,ADMP/4 th IO EMG:?/AH,ADMP/4 th IO