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MSKCase-BasedTeaching Case1 Suyash Poshakwale The Case Maria, a 32-year-old teacher, visits her GP with a 6-month history of: • Intermittent tingling and numbness in her right hand, especially the fourth and fifth fingers. • Weakness in gripping objects, often dropping items such as pens and coffee mugs. • Cold, pale discoloration of the hand during stress or cold weather. • Recently noticed drooping of her right eyelid and a smaller pupil on the same side, which she describes as persistent. She denies significant pain but reports occasional aching in her right shoulder, which worsens after prolonged teaching sessions, particularly when raising her arm overhead. Her past medical history includes a minor car accident two years ago, where she sustained a whiplash injury.Dissectingthe presentation • What keyfeatures in Maria’s symptomsstandout? • Howwouldyoucategorize her symptoms(e.g., sensory,motor, autonomic,vascular)? • What anatomical regions mightbe involvedbased on her presentation?Maria’spresentation • Mariapresentswith acombinationof symptomsthat canbecategorized as: 1.Sensorysymptoms: Tingling andnumbness inthefourthandfifthfingers. These correspondto the C8-T1 dermatomes, suggesting involvement of the lower trunk ofthebrachial plexus. 2.Motor symptoms: Weakness in gripandmuscle wasting ofthe interossei muscles.Theseare suppliedby the ulnar nerve, whichis derivedfrom the lower trunk ofthebrachial plexus. 3.Autonomicsymptoms: Right-sided ptosis,miosis, and possiblemild anhidrosis(Horner’ssyndrome). These indicate involvement of the sympatheticchain, whichrunsclosetothe thoracic outlet. 4.Vascular symptoms: Cold and pale handwith delayedcapillary refill, flow tothe hand.ntermittent subclavianartery compression,reducing bloodFoodforthought • What nerves are responsible for innervating the hand muscles? • More specifically,whatmuscles in the handare innervatedby what nerves and howdoes thisrelate to Maria’s presentation? • What about sensory innervation? UpperLimb DermatomesHandmusclesandtheirinnervationHandinnervation SensoryInnervation: MotorInnervation: 1.Median Nerve: 1. Median Nerve: 1. PalmarSurface: Lateral3½fingers(thumb,index,middle,and 1. Innervates: 1. Thenar muscles: lateral halfoftheringfinger). 1. Abductor pollicis brevis (APB) 2. Dorsal Surface:Tipsof the samefingers. 2. Opponens pollicis (OP) 3. Flexor pollicis brevis (FPB, superficialhead) 3. ClinicalSignificance:Compression leadsto sensorysymptoms 2. Lateraltwo lumbricals (1st and 2nd) inthisdistribution,asseenin carpal tunnelsyndrome. 2. Role: 1. Thumb opposition, abduction,and flexion. 2. UlnarNerve: 2. Flexion of themetacarpophalangeal (MCP)joints of the indexand middle fingers while extending the interphalangeal(IP) joints. 1. PalmarSurface: Medial1½fingers(little andmedial halfofthe 2. UlnarNerve: 1. Innervates: ringfinger). 1. Hypothenar muscles: 2. Dorsal Surface:Samedistribution. 1. Abductor digiti minimi 2. Flexor digitiminimi 3. ClinicalSignificance:Compression at thethoracic outlet or 3. Opponens digitiminimi 2. Medial two lumbricals (3rd and 4th) Guyon’scanal causessensory deficitsinthisregion,asinMaria's 3. Palmar and dorsalinterossei case. 4. Adductor pollicis 5. Palmaris brevis 3.RadialNerve: 2. Role: 1. Dorsal Surface:Lateralaspectofthedorsumofthehand(not 1. Finger abduction and adduction (interossei). 2. Adduction ofthe thumb (adductor pollicis). includingthefingertips). 3. Flexion and extension of thering and little fingers (lumbricals). 2. ClinicalSignificance:Doesnotusuallycausesensory 3. RadialNerve: 1. Innervates: None of the intrinsic hand muscles but controls extension ofthe symptomsin TOS. wrist and fingers via extrinsic muscles in the forearm.BacktoMaria…. 1.Motor Symptoms: 1.Mariahas muscle wasting in theinterossei andhypothenarmuscles,which are innervatedby the ulnar nerve.This indicates compression of the brachial plexus's lower trunk (C8-T1). 2.Weak gripstrength also points to ulnar nervedysfunction,which affects the interossei andmediallumbricals. 2.SensorySymptoms: 1.Tingling and numbness in the4th and5th fingers (ulnar nervedistribution) further supportcompression of thelower trunk of thebrachialplexus,where the ulnar nerveoriginates. 2.No involvementofthe median nerve suggests that compression is localized to the ulnar components of the lower trunk,sparing thelateraltrunk (C5-C7).Based on the anatomy and Maria’s presentation, what are the possible causes of her symptoms? List structural or functional abnormalities that might explain thoracic outlet compression.ThoracicOutletSyndrome (TOS) • Anatomical causes: • Cervical rib (osseous anomaly). • Scalenemuscle hypertrophy or fibrous bands (soft tissue anomalies). • Postural abnormalities (droopingshoulders,forward head posture). • Functionalcauses: History of trauma,like whiplash,mayhave triggeredsymptoms byaggravating pre-existing anatomical predispositions.Different typesofTOS • Neurogenic TOS: Compression ofthe C8-T1 nerves causing sensory and motor deficits. • VascularTOS: Subclavian arterycompression causing claudication,or subclavian vein compression causing swelling. • Disruption of the sympathetic chain near the thoracic outlet leads to ptosis, miosis,and anhidrosis (suggestive of?)InvestigationsandAbnormalities? 1.Imaging: 1.X-rays: Lookforacervical riborotherosseous anomalies. 2.MRI/CT: Assesssofttissue (scalenemuscles, fibrousbands) and brachial plexusstructures. 2.VascularStudies: 1.Dopplerultrasound: Evaluatesubclavianartery/veincompression. 2.Venography orangiography: Identify vascularabnormalities. 3.SpecializedTests: 1.Anteriorscaleneblock: DiagnosticandtherapeuticforneurogenicTOS.CervicalRibWhatisthe diagnosis? 1. Neurogenic TOS 2. Cervicalradiculopathy 3. CarpalTunnel Syndrome 4. Vascular TOS 5. C-Spine injuryWhatisthe diagnosis? 1. Neurogenic TOS 2. Cervicalradiculopathy 3. CarpalTunnel Syndrome 4. Vascular TOS 5. C-Spine injuryHowtomanagesomeonewithTOS • ConservativeManagement: • Educationandposture correction. • Physical therapy forscalene musclerelaxationandstrengthening. • Surgical Intervention: • Indicated for persistent symptomsorconfirmed anatomical anomalies (e.g., resectionof cervical rib orfibrousbands). • Post-Treatment Care: • Monitorforresolutionof Horner’ssyndrome and vascularsymptoms. • Gradual returntodaily activities.Maria’smanagement 1.Initiate conservative management(education,physical therapy, ergonomic adjustments). 2.Conductimaging and diagnostic tests to confirmstructural anomalies. 3.Consider surgicalintervention if symptoms persist after 3–6 monthsof conservative therapy or ifimaging revealssevere anatomical compression. 4.Provide post-operative rehabilitation andlong-termfollow-up to ensure symptom resolution.