Neuropathies Notes


Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Neuropathies essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Neuropathies:

Winged scapula

Carpal tunnel syndrome

Erb-Duchenne palsy

Klumpke paralysis


Thoracic outlet syndrome

Ulnar claw

NOTES NOTES NEUROPATHIES GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Peripheral nervous system (PNS) disorders caused by neuronal damage SIGNS & SYMPTOMS ▪ Impairment/loss of motor/somatosensory function; “pins and needles” sensation (paresthesia) DIAGNOSIS ▪ History: characteristic symptoms, sometimes preceding injury DIAGNOSTIC IMAGING ▪ Imaging for some conditions OTHER DIAGNOSTICS ▪ Electromyography (EMG), nerve conduction studies (NCS) TREATMENT MEDICATIONS ▪ For neuropathic pain SURGERY ▪ Surgery to relieve nerve compression 666 OSMOSIS.ORG OTHER INTERVENTIONS ▪ Physiotherapy ▫ Helps restore muscle function (if nerves are not severed → may help motor function with partial lesions) ▪ Splinting (e.g. wrist, ankle) MNEMONIC: DANG THERAPIST Peripheral neuropathies common differential diagnosis Diabetes Amyloid Nutritional (e.g. B12 deficiency) Guillain-Barre Toxic (e.g. amiodarone) Hereditary (Charcot-MarieTooth) Endocrine Recurring (10% of Guillain– Barre) Alcohol Pb (lead) Idiopathic Sarcoid Thyroid
Chapter 86 Neuropathies CARPAL TUNNEL SYNDROME PATHOLOGY & CAUSES SIGNS & SYMPTOMS ▪ Nerve entrapment disorder → compression of wrist’s median nerve ▫ Median nerve passes through carpal tunnel ▪ Carpal tunnel ▫ Floor: carpal arch ▫ Roof: flexor retinaculum (transverse carpal ligament) ▫ Contains nine flexors, median nerve ▪ Repetitive stress injury in susceptible people → inflammation → edema → fluid in narrow space compresses structures → nerve injury, impaired neuronal transport/ vessel compression, nerve ischemia ▪ Usually unilateral symptoms ▪ Individual may awake with numbness, tingling (after day of use → worsens at night) ▪ Initially dull ache, discomfort; paresthesia, sharp pain extending to forearm ▪ Pain, numbness, tingling in thumb, index finger, middle finger, thumb side of ring finger on palmar side of hand ▪ Clumsiness, dropping small objects ▪ No sensation loss in palm’s central region ▫ Palmar branch of median nerve innervates it, branches off before going through carpal tunnel CAUSES ▪ Tendonitis, edema, repetitive stress injury (typing) RISK FACTORS ▪ Obesity, pregnancy, other underlying conditions (rheumatoid arthritis), trauma, genetic predisposition, occupation COMPLICATIONS ▪ Thenar muscle atrophy MNEMONIC: TRAMP Carpal tunnel syndrome common causes Trauma (occupational) Rheumatoid arthritis Acromegaly Myxoedema Pregnancy DIAGNOSIS OTHER DIAGNOSTICS EMG ▪ Identifies neuropathic changes (sharp waves, ↑ insertional activity) NCS ▪ ↓ response amplitude Physical exam ▪ Findings that support diagnosis ▫ Phalen maneuver: pressing of upper hands together while flexing wrists induces pain ▫ Tinel’s sign: tapping on wrist over median nerve elicits pain ▫ Durkan’s test: pressing of median nerve for 30 seconds worsens symptoms ▫ Thenar eminence atrophy OSMOSIS.ORG 667
MNEMONIC: WRIST TREATMENT Carpal tunnel syndrome treatment Wear splints at night Rest Inject steroid Surgical decompression Take diuretics MEDICATIONS ▪ Corticosteroid injections → ↓ inflammation SURGERY ▪ If symptoms persist, cut transverse ligament to relieve pressure OTHER INTERVENTIONS ▪ Behavior modification (e.g. adjusting typing position, weight loss) ▪ Wrist supports, splints ▪ Physical therapy ▫ Helps relieve wrist strain, ↓ symptom severity Figure 86.1 Relative wasting of the right thenar eminence in a case of carpal tunnel syndrome. ERB–DUCHENNE PALSY PATHOLOGY & CAUSES ▪ Type of neonatal brachial plexus palsy ▫ Caused by upper part of brachial plexus injury ▫ AKA Erb’s palsy ▫ Brachial plexus: group of nerves provide movement, feeling to shoulder, arm, hand, fingers; roots included in plexus are C5–T1 forming superior, middle, inferior trunks which form lateral, posterior, medial cords ▪ Nerves affected ▫ Axillary ▫ Musculocutaneous (biceps brachii, brachioradialis) ▫ Suprascapular 668 OSMOSIS.ORG ▪ Upper brachial plexus stretching → nerve damage TYPES ▪ Brachial plexus injuries ▫ Neuropraxia (most common, nerve stretched but not torn) ▫ Avulsion (most severe, roots torn from spinal cord) ▫ Rupture (nerve torn) ▫ Neuroma (nerve torn → healed, scar puts pressure on injured nerve) RISK FACTORS ▪ Shoulder dystocia, macrosomia, malpresentation, maternal obesity, cephalopelvic disproportion, prolonged/
Chapter 86 Neuropathies difficult labor, precipitous delivery COMPLICATIONS ▪ Affected arm grows shorter than other ▪ Limited range of motion ▪ Muscle weakness SIGNS & SYMPTOMS ▪ “Waiter’s tip” ▫ Hanging arm rotated medially, extended forearm, fixed wrist ▪ Affected arm may be held against body; flaccid, flexed at elbow ▪ Lateral part of forearm sensation loss, circulatory disturbances, paralysis ▪ Asymmetric Moro reflex ▫ Infant spreads only one arm (instead of two) when it feels like it’s falling DIAGNOSIS DIAGNOSTIC IMAGING X-ray ▪ Rule-out fracture Ultrasound ▪ May show shoulder dislocation OTHER DIAGNOSTICS ▪ Neurological exam ▫ Difficult due to limited child movement ▫ Involves evaluation of arm range of movement, motility Electromyoneurography (EMNG) ▪ Shows damage extent TREATMENT SURGERY ▪ Nerve repair/reconstruction OTHER INTERVENTIONS ▪ Physical therapy ▫ Promotes muscle strengthening, normal function Figure 86.2 An illustration of the “waiter’s tip” position. OSMOSIS.ORG 669
KLUMPKE PARALYSIS PATHOLOGY & CAUSES ▪ Type of brachial plexus palsy affecting lower brachial plexus nerve roots C8–T1 ▪ Abducted arm during childbirth → arm traction, pulling → nerve stretching in inferior brachial plexus area → brachial plexus damage CAUSES ▪ Obstetric injury in adulthood ▫ Caused by grabbing things when falling from height RISK FACTORS ▪ Birth injury ▫ Macrosomia, cephalopelvic disproportion, shoulder dystocia, prolonged/difficult labor, precipitous delivery, abnormal presentations ▪ Adult trauma ▫ Car crashes, falls, contact sports COMPLICATIONS ▪ Severe pain, arm immobility SIGNS & SYMPTOMS ▪ Claw hand ▫ Intrinsic hand muscle atrophy → flexion of interphalangeal, extension of metacarpophalangeal joints ▪ Sensation loss in appropriate dermatome (medial side of arm), upper-arm weakness Horner’s syndrome ▪ Ptosis (drooping eyelid) ▪ Enophthalmos (deep-set eye) ▪ Miosis (constricted pupil) ▪ ↓ sweating on one side of face 670 OSMOSIS.ORG Figure 86.3 An illustration of the claw hand position. DIAGNOSIS OTHER DIAGNOSTICS ▪ Clinical diagnosis through neurological exam ▫ Testing mobility, sensation, Horner’s syndrome symptoms EMG/NCS ▪ Confirms lesion location, assesses severity TREATMENT OTHER INTERVENTIONS ▪ Physiotherapy, electrical nerve stimulation, occupational therapy ▪ Repositioning, splinting (extreme damage cases)
Chapter 86 Neuropathies SCIATICA PATHOLOGY & CAUSES SIGNS & SYMPTOMS ▪ Type of neuralgia following sciatic nerve along its distribution path ▪ Lumbosacral radiculopathy (spinal nerve root disorder) → radicular (radiating, shooting) pain ▪ Most commonly caused by spinal disc disease → narrowing of neural foramen/ intraspinal space → disc profusion outside spinal column border → lumbar/sacral nerve root compression → nerve irritation ▪ Sudden shooting pain onset radiating from lumbar spine → down leg → areas innervated by sciatic nerve (side, back) ▫ Mostly unilateral ▪ Pain may involve lower back, hip, foot ▪ Numbness, muscle weakness, burning sensation CAUSES DIAGNOSTIC IMAGING ▪ Spinal disc herniation (most common) ▪ Spinal stenosis (spinal canal narrowing) ▪ Piriformis syndrome ▫ Rare variation of sciatic nerve passing through piriformis muscle → symptoms ▪ Pregnancy ▫ Due to ligament loosening, shifting of center of gravity pressure on nerve ▪ Nerve tumors (schwannoma), trauma ▪ Younger individuals ▫ Infection DIAGNOSIS X-ray, MRI ▪ Confirms disc herniation, stenosis, tumors as etiology; determines management OTHER DIAGNOSTICS ▪ Clinically diagnosed ▫ Straight leg raise test: passive straight leg raising between 30–70° while lying down, produces Lasègue’s sign (positive if pain present); not very specific ▫ Crossed straight leg raising test: has higher specificity, not very sensitive RISK FACTORS ▪ Preexisting spinal disorders ▪ Age: ↑ risk ▪ Biologically-male individuals COMPLICATIONS ▪ Nerve damage, muscle atrophy, immobility, permanent sensation loss TREATMENT MEDICATIONS ▪ Pain management (nonsteroidal antiinflammatory drugs (NSAIDs), opioids) SURGERY ▪ Spinal disc repair (severe symptoms) OTHER INTERVENTIONS ▪ Recommend normal activity OSMOSIS.ORG 671
THORACIC OUTLET SYNDROME PATHOLOGY & CAUSES ▪ Compression of neurovascular bundle in space between clavicle, first rib; traverses thoracic outlet ▫ Can result from combination of developmental abnormalities, injuries, physical activities that predispose neurovascular compression TYPES Structures involved ▪ Neurogenic ▫ Brachial plexus compressed ▫ Most common ▪ Venous ▫ Subclavian vein ▪ Arterial ▫ Subclavian artery Obstruction areas ▪ Anterior scalene ▫ Inflammation/structural anomaly (multiple attachments) → scalene muscle presses down onto structures, brachial plexus compressed ▫ Most common ▪ Cervical rib ▫ Congenital abnormality of additional rib, subclavian vein compressed ▫ More common in biologically-female individuals ▪ Costoclavicular ▫ All structures may be involved ▫ Second most common CAUSES ▪ Repetitive motion → chronic inflammation ▪ Congenital ▫ Cervical rib, supernumerary muscle insertions ▪ Neck hyperextensions 672 OSMOSIS.ORG RISK FACTORS ▪ Coagulation disorders, pregnancy, tumors, trauma ▪ Repetitive movement sports (swimming, handball) COMPLICATIONS ▪ Stroke (arising from retrograde thrombi); deep venous thrombosis; arterial thromboembolism; atrophy; neural damage, paralysis; limb ischemia SIGNS & SYMPTOMS ▪ Differ according to structure involved, unilateral presentation more common ▪ Neurogenic ▫ Pain, numbness, paresthesia (tingling), weakness when raising arm, muscle atrophy (thumb muscles) ▪ Venous ▫ Swollen, painful, cyanotic (blue) arm; spontaneous edema, may cause paresthesia ▪ Arterial ▫ Cold, painful, pale arm; ↓ systolic blood pressure in affected arm, diminished distal pulses, aneurysmal change in artery after compression may → thrill over subclavian artery; thromboembolism → worsening symptoms, ischemia DIAGNOSIS DIAGNOSTIC IMAGING Upper-extremity ultrasound, angiography ▪ Shows blood clot formation in vessels; distinguishes between arterial, venous etiology
Chapter 86 Neuropathies Chest X-ray ▪ Identifies bone abnormalities TREATMENT CT scan ▪ Identifies compression areas in greater detail MRI ▪ Identifies brachial plexus compression, contrast displays vessel occlusion level OTHER DIAGNOSTICS Physical exam ▪ Examine limbs for signs of neural, venous/ arterial insufficiency ▪ Blood pressure difference between arms indicates arterial involvement ▪ Adson test: raising arms above head induces further compression → distal pulse diminishment MEDICATIONS ▪ Local corticosteroid, anesthetic injections (symptom relief) ▪ Thrombolysis (in vascular clot cases) SURGERY ▪ Decompression techniques OTHER INTERVENTIONS ▪ Physical therapy ▫ Stretching, exercise EMNG ▪ Confirms neurological dysfunction ULNAR CLAW PATHOLOGY & CAUSES ▪ Two medial fingers (fourth, fifth) become flexed at interphalangeal level, extended at metacarpophalangeal level ▫ Due to ulnar nerve damage, hand resembles “claw” ▪ Prolonged ulnar nerve pathway pressure → nerve injury → hand muscle wasting (except thenar, two lateral lumbricals); flexor carpi ulnaris, flexor digitorum profundus → fourth, fifth finger flexion at interphalangeal joint, extension at metacarpophalangeal joint Injury level ▪ Low ▫ Wrist, damage usually more severe ▫ Lesion site of nerve within wrist area doesn’t influence symptoms ▫ Cause: usually trauma/repetitive movement ▪ High ▫ Cause: regularly leaning against elbows CAUSES ▪ Prolonged pressure on Guyon’s canal (where ulnar nerve passes) ▪ Trauma RISK FACTORS ▪ Biologically-male individuals: ↑ BMI ▪ Biologically-female individuals: ↓ BMI ▪ Cubitus valgus (forearm at pathological angle) ▪ Cycling ▪ Leaning against desk OSMOSIS.ORG 673
▪ Tool use requiring downward pressure (musical instruments) COMPLICATIONS ▪ Nerve palsy SIGNS & SYMPTOMS ▪ Range in severity from mild intermittent paresthesia to complete sensation loss, atrophy ▪ Flexion at interphalangeal joints, extension at metacarpophalangeal ▪ Weakness, dexterity loss DIAGNOSIS DIAGNOSTIC IMAGING Ultrasound ▪ Identifies local inflammation in Guyon’s canal (where ulnar nerve passes) MRI ▪ Identifies nerve thickening OTHER DIAGNOSTICS Clinical exam ▪ Identify injury level ▫ Elbow has different muscles involved (flexor carpi ulnaris, flexor digitorum profundus) ▫ Froment’s sign: card gripped using interphalangeal joints (abductor pollicis weak) ▫ Finger abduction, pressing hands together causes one side to collapse EMNG ▪ Identifies neural damage level in fingers TREATMENT SURGERY ▪ Severe injury ▫ Nerve decompression at level of Guyon’s canal OTHER INTERVENTIONS ▪ Lighter injury ▫ Physical therapy, occupational therapy ▪ Splints, avoiding exacerbation Figure 86.4 A left hand demonstrating an ulnar claw. 674 OSMOSIS.ORG
Chapter 86 Neuropathies WINGED SCAPULA PATHOLOGY & CAUSES DIAGNOSIS ▪ Abnormal scapula protrusion from back of chest wall, usually unilateral ▫ AKA scapula alata ▪ Caused by muscle weakness ▫ Serratus anterior: damage either to brachial plexus, long thoracic nerve (most common) ▫ Trapezius: damage to accessory nerve ▫ Rhomboid: damage to dorsal scapular nerve ▪ Nerve damage, irritation/muscular dystrophy → muscle weakness → scapula elevation from thoracic wall → scapula winging DIAGNOSTIC IMAGING RISK FACTORS OTHER INTERVENTIONS Neck lymphadenectomy Neuromuscular disorder Idiopathic Traumatic ▫ Neck injury, repetitive movement, backpack straps, sleeping in bad position, surgery ▪ Non-traumatic ▫ Viral neuritis (influenza), allergy, toxic; neuromuscular disorders (facioscapulohumeral muscular dystrophy) ▪ ▪ ▪ ▪ X-ray ▪ Confirms absence of fractures, structural irregularities OTHER DIAGNOSTICS ▪ Scapular asymmetry, winging TREATMENT SURGERY ▪ Nerve transfer, scapular fixation ▪ May resolve spontaneously ▪ Massage therapy ▫ Muscle relaxation ▪ Physical therapy ▫ Improves shoulder weakness COMPLICATIONS ▪ Compensatory back muscle imbalance SIGNS & SYMPTOMS ▪ ▪ ▪ ▪ Fatigue Neck, shoulder pain Scapular winging, shoulder asymmetry Muscle weakness, difficulty lifting objects, difficulty raising arm above head Figure 86.5 Winged scapula in an individual with a long thoracic nerve palsy. OSMOSIS.ORG 675

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Neuropathies essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Neuropathies by visiting the associated Learn Page.