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NERVE: PROXIMAL MOTOR

Brachial neuropathies   Acquired   Hereditary   Radiation vs Neoplastic Demyelinating neuropathies Diabetic amyotrophy Lumbosacral plexopathies   Types   Radiation vs Neoplastic Myopathy Progressive motor neuropathies Rule out Spinal muscular atrophy Thoracic outlet syndromes

• Demyelinating Neuropathies (with conduction block)
  • Guillain Barré
  • CIDP
• Acute Axonal Motor Neuropathy
  • Associated with Campylobacter jejuni, or IgG vs GM1 ganglioside: Usually Distal > Proximal
  • Porphyria
• Proximal Lower Motor Neuron Syndrome
• Hereditary Spinal Muscular Atrophies:
  • SMA 5q
  • X-BSMA
  • HMSN-P
  • Other
• Lumbosacral plexopathies
  • Diabetic Amyotrophy
  • Radiation
  • Neoplastic
  • Immune
  • Hereditary: Neuralgic amyotrophy; HNPP
  • Circulatory
    • Ischemic plexopathy
    • Hemorrhage
    • Arterial injections
  • Differential diagnosis:
    • Cauda equina lesion
    • Hip disease
    • Lumbosacral radiculopathy
  • Episodic lumbosacral weakness
    • Cauda equina lesion
    • Ischemic plexopathy
    • Peripheral arterial occlusive disease
• Brachial Neuropathy
• Rule out
  • Orthopedic disorders: Rotator cuff injury; Shoulder joint contractures; Hip disease
  • Mononeuropathies: Axillary, Suprascapular, Dorsal scapular, Spinal accessory
  • Myopathy

BRACHIAL NEUROPATHIES

Brachial Plexus Structure   Upper extremity innervation   Cervical radiculopathy Hereditary disorders   HNPP   HNA: Acute attacks   HNA2: Chronic, Undulating   HNA3: Acute attacks Acquired disorders   Diagnoses by anatomy     Supraclavicular       Lower plexus       Upper plexus     Infraclavicular     Root avulsion   Types     Burner syndrome     Gunshot wounds     Heroin     Neonatal (Obstetric)     Neoplastic     Neuralgic amyotrophy     Postoperative     Radiation     Rucksack paralysis     Thoracic outlet syndromes     Traction

Brachial Plexus: Structure⁸

ACQUIRED BRACHIAL PLEXOPATHIES
Differential diagnosis by anatomy

• Upper plexus
  • Clinical features
    • Most common site of brachial plexus lesion
    • C5, C6, Roots or Upper trunk
    • Arm: Adducted by trunk; Extended at elbow; Internally rotated
    • Sensory loss
      • Nerves: Axillary & Lateral antbrachial cutaneous
      • Distribution: Over lateral deltoid & arm; May extend ot thumb
    • Frequent spontaneous recovery
    • Tendon reflexes lost: Biceps & Brachioradialis
  • NCV: Nerves commonly affected
    • Motor: Axillary (Deltoid); Musculocutaneous (Biceps); Suprascapular
    • Sensory: Lateral antebrachial cutaneous; Median nerve at 1st digit
  • Specific syndromes
    • Neuralgic amyotrophy
    • Rucksack paralysis
    • "Burner" syndrome
    • Partial post-anesthesia paralysis
    • Neonatal (Erb)
    • Infections: Lyme; Erlichiosis
    • Traction injuries
    • Vasculitis
    • Heroin
• Middle trunk
  • Primarily derived from C7
  • Weakness: Triceps; Flexor carpi radialis; Pronator teres
  • Sensory loss: Middle finger
  • Tendon reflex lost: Triceps
  • Uncommon
• Lower plexus
  • Clinical features
    • C8, T1, Roots or Lower trunk
    • Nerves supplied by lower trunk
      • Ulnar
      • Medial brachial cutaneous
      • Medial antebrachial cutaneous
      • Partial: Median; Radial
    • Sensory loss: Especially medial forearm ± hand
    • Less recovery than upper plexus lesions
    • Other
      • Pure lower trunk lesions: Tendon reflexes normal
      • Klumpke paralysis: Wasted & weak medial forearm & hand
  • NCV: Nerves commonly affected
    • Median & Ulnar
  • Specific syndromes
    • Neoplasia
      • Metastatic
      • Pancoast
      • Neurofibroma; Schwannoma; Meningioma
    • Post-sternotomy
    • Thoracic outlet syndrome (neurogenic)

• Clinical features
  • General
    • Cords or terminal nerves affected
    • Less regional proclivity than supraclavicular lesions
    • Better recovery than supraclavicular lesions
  • Lateral cord
    • Nerves
      • Musculocutaneous
      • C6-C7 portion of median
    • Weakness: Elbow flexion; Forearm pronation; Wrist flexion (Flexor carpi radialis)
    • Sensory loss: Anterolateral forearm & hand
    • Reflex loss: Biceps
  • Medial cord
    • Anatomy: Anterior division of lower trunk
      • Similar to lower trunk lesions: Except intact radial C8 axons
    • Weakness
      • All ulnar & C8-T1 innervated median muscles
      • Finger flexion, extension & abduction; Ulnar wrist flexion
      • Spared: Finger extensors
    • Sensory loss: Medial arm forearm & hand
  • Posterior cord
    • Nerves: Radial; Axillary; Thoracodorsal
    • Weakness
      • Arm abduction & adduction, forward elevation & extension
      • Extension of forearm, wrist & fingers
    • Sensory loss: Variable over deltoid, posterior arm & forearm & base of thumb
    • Tendon reflex loss: Brachioradialis; Triceps
• Specific syndromes
  • Radiation: Axillary lymph nodes; Lateral cord
  • Gunshot
  • Fractures
    • Humeral
    • Midshaft clavicular: Medial cord
  • Medical Procedures
    • Orthopedic
      
    • Plexus block
      
    • Axillary arteriography
  • Neurovascular disorders
  • Medial brachial fascial compartment syndrome

• Traction: Most common
  
• More severe trauma, metastatic, radiation, neurovascular
• Mass lesion
  • Subclavian artery aneurysm: May be related to Behçet's disease

• Associations
  • Trauma: Traction
  • Brachial plexus injury
  • Less common: Fractures & Dislocations of cervical spine
  • Upper-extremity position at time of injury
    • C5–C6 fibers: Most susceptible with upper extremity alongside the torso
    • C7 fibers: Most susceptible with upper extremity oriented parallel to floor
    • C8–T1 fibers: Most susceptible with upper extremity in above-shoulder position
    • Strong enough traction avulses all roots, regardless of limb position
  • Concomitant nerve injuries may occur: Axillary, Musculocutaneous, Suprascapular
• Anatomy: Lower roots (C8 & T1) more commonly damaged
• Clinical
  • Weakness
    • Proximal ± Distal muscles: Levator scapulae; Serratus anterior
  • Sensory features
    • Pain
      • Common
      • Often severe
      • More with greater injury
      • Location: Often in hand
    • Prognosis: Little or no recovery
    • Electrophysiology: Reduced in regions with normal sensory action potentials
  • Treatment: Surgical repair not possible
• Lab
  • Electrodiagnostic studies: Proximal; Preganglionic lesion
    • Paraspinous denervation
    • Motor potentials (CMAPs): Reduced amplitudes
    • Sensory potentials (SNAPs): Normal
  • Myelography: Traumatic meningocoeles filling with dye
  • Axon reflex: Normal skin flare to histamine in preganglionic lesion

ACQUIRED BRACHIAL PLEXOPATHIES: Types

General: Vulnerability to trauma or compression

• Size: Large
• Location: Superficial
• Position: Between two highly mobile structures (neck and upper extremity)
• Neighboring structures
  • Lungs
  • Vessels
  • Skeletal
  • Muscular

Brachial plexus: Traction lesions

• Brachial plexus & roots susceptible to traction
  • May be injured without major damage to neighboring structures
  • Roots especially at risk
• Usually closed lesion
  • Incomplete
  • High magnitude stretch forces over brief period
  • Often associated with contusion
• Stretch with
  • Birth
  • Injury or fracture: Motorcycle accidents
  • Anesthesia
• Location of damage
  • Supraclavicular plexus: Common
  • Avulsion: C8 & T1; Ventral more common
  • Extraforaminal tear: C5 to C7 roots
• Pain
  • Common in all forms of plexus injury
  • Worst with Root avulsion
    • Constant background pain + Paroxysmal shocks
    • Temperature: Pain increased by Cold & reduced by warmth
• Prognosis: Poorer recovery after root avulsion

Postoperative paralysis

• Operation
  • Type: Especially abdominal (Cholecystectomy; Hysterectomy)
  • Positions
    • Supine
      • Trendelenburg
      • Arm abduction (esp. both)
      • Arm restraint on board in extension, abduction, external rotation
      • Head: Rotation & Lateral flexion to opposite side
    • Lateral: Lower shoulder & arm under rib cage + Poor padding
    • Upper arm abducted & forearm pronated
  • Injury type: Traction or Pressure
• Onset
  • Time: Immediate postoperative
  • Weakness
  • Sensory: Paresthesias; Pain not prominent
• Distribution
  • Unilateral
  • Upper or total plexus
• Recovery
  • Onset: After 2 to 3 weeks
  • Progression of recvovery
    1. Sensory first
    2. Lower plexus strength
    3. Upper plexus strength
  • Mostly complete after months, occasionally year
  • Best with partial plexus lesions
• Electrophysiology
  • Motor: Conduction block
  • Sensory: Often normal SNAPs

Post-Medial Sternotomy Paralysis

• Operation: Coronary artery bypass grafts
• Anatomical distribution
  • C8 radiculopathy: Lower (Trunk) plexus
  • Damage caused by 1st thoracic rib
• Clinical
  • Weakness: Ulnar distribution in hand
  • Sensory: Paresthesias & sensory loss in medial (ulnar) hand
  • Pain: Medial hand; In more severe lesions
• Electrophysiology
  • Ulnar sensory potential: Reduced amplitude
  • Ulnar motor: ± Reduced amplitude
  • Normal in most: Medial antebrachial cutaneous
  • EMG: C8 denervation
• Pathology: Fracture of 1st rib at costotransverse articulation
• Recovery: Most resolve by 4 months

Neuralgic amyotrophy

• Nosology: Also called
  • Parsonage-Turner syndrome
  • Brachial neuritis
• Onset
  • Sudden
  • Pain: Most commonly over lateral deltoid
  • Commonly at night
• Epidemiology
  • Male:Female = 2.5:1
  • Right > Left
  • Age: Young & middle aged adults; Range 20 to 70 years
  • Incidence: 1.6 per 100,000
  • Also see: Hereditary brachial plexopathies
• Prodromes
  • Antecedent illness (25% to 50%): Upper respiratory; Immunization
  • Other: Childbirth; Surgery
• Clinical
  • Weakness: Often patchy
    • Onset: Often as pain is subsiding
    • Maximal: Onset to 2 weeks
    • Distribution
      • Proximal arm: Deltoid; Serratus anterior; Supraspinatus; Infraspinatus
      • Other regions of weakness
        • Anterior interosseus nerve (Distal thumb flexion)
        • Pronator teres
        • Musculocutaneous
        • Diaphragm
      • Bilateral in 20%: Sequential onset; Asymmetric
    • Often severe in affected extremity
  • Atrophy: Prominent
  • Sensory loss
    • Distribution: Over lateral deltoid, or Forearm
    • Severity: Mild
  • Pain
    • Shoulder & scapular region
    • Maximal at onset
    • Acute: Persists hours to 2 weeks
    • Chronic: Ache may persist for months
  • Tendon reflexes: Normal unless musculocutaneous nerve involved
• Lab
  • CSF: Normal
  • NCV: Routine nerves often unremarkable
    • Sensory abnormal more than motor
    • Abnormal lateral antebrachial cutaneous in 50%
    • Axonal loss in affected muscles: Small CMAPs
  • EMG: Denervation
    • In regions of nerves arising from brachial plexus
    • Other nerves may also be involved: Phrenic; Spinal accessory; Laryngeal
    • Patchy distribution: May be differential fascicular involvement
    • Denervation may be bilateral in clinically unilateral syndrome
• Prognosis
  • Improvement begins after 1 or more months
  • 90% with functional recovery after 4 years
• Treatment: Pain control; ? Benefit from corticosteroids
• Childhood (< 16 years) variant⁵
  • Male:Female 1.8 to 1
  • Onset age: Median 3 years; Range 3 days to 15 years
  • Prodrome
    • Upper respiratory infection: Onset before weakness
    • Osteomyelitis (Shoulder or Humerus): Newborns; Onset after weakness
  • Weakness
    • Acute onset
    • Unilateral
    • Arm
    • Proximal & Distal
  • Pain (50%)
  • Recovery
    • Full: Often in 6 months; 65%
    • Partial: 25%
    • None: 10%
  • Rule out
    • Hereditary neuralgic amyotrophy
    • HNPP

Rucksack paralysis

• Predisposing factors
  • Pack used without waist support
  • Prior anomaly or injury: Cervical rib; Vertebral anomaly
  • Greater weight
  • Longer duration of load
• Weakness
  • Full syndrome may be preceded by transient weakness
  • Upper & middle trunks + occasional individual nerves
    • Lateral shoulder & upper arm
    • Shoulder: Deltoid; Supraspinatus; Infraspinatus; Serratus anterior
    • Other: Triceps; Biceps; Wrist extensors
  • Dominant or non-dominant arm
• Sensation
  • Paresthesias but no pain
  • Loss: Normal or patchy change on exam
• Electrophysiology
  • Conduction block: 67%
  • Axonal loss in 1/3
• Prognosis
  • 2/3 with recovery in 3 months
  • Less recovery with axonal loss

"Burner" syndrome

• Injury
  • Sudden forceful depression of shoulder
  • Occurs in contact sports: Football
• Weakness
  • 1 upper limb
• Sensory
  • Pain
    • Onset: Sudden
    • Duration: Transient (minutes)
    • Burning dysesthesia
    • Distribution: C6; May extend to thumb
  • Reduced sensation: May be in whole limb
• Course
  • Most resolve in minutes
  • Occasional longer term change: Upper trunk distribution
  • Recovery: Asymptomatic patients may have mild residual EMG signs
  • Recurrence: With repeated injury

Thoracic outlet syndromes

• Arterial vascular: Major
  • Unilateral
  • Rib changes: Full cervical rib
  • Sex: Male = Female
  • Vascular
    • Subclavian artery compression with post stenotic dilatation
    • Subclavian artery aneurysm
      • May be related to Behçet's disease
      • May present with severe arm weakness & pain
  • Clinical syndrome: Unilateral hand & finger ischemia; Pain
• Arterial vascular: Minor
  • Hyperabduction of arm: Pain; Reduced pulse
  • Young adults
  • Rib changes: None
• Neurogenic
  • Epidemiology
    • Male > Female: 9 to 1
    • Age: Mean 4th decade; Range 2nd to 8th decade
  • Pathology
    • Rib changes
      • X-ray:
        • Rudimentary cervical rib, or Elongated C7 transverse process
        • Usually bilateral change
      • Radiolucent fibrous band from 1st rib to above process
    • Lower plexus: Stretched & angulated over band
    • Functional anatomy: T1 root compression
  • Clinical
    • Unilateral signs
    • Onset: Pain
    • Sensory loss: Minor
      • Forearm & Arm: Medial
      • Hand: ± Ulnar 2 fingers
    • Pain & Paresthesias
      • Intermittent
      • Medial forearm, arm ± 2 fingers
    • Weakness
      • Distal
      • Thenar > Hypothenar
    • Wasting
      • Distribution: Thenar
      • Poorer prognosis for recovery after surgery
    • Course
      • Very slowly progressive: Years
  • Associated anomalies
    • Cervical rib
    • Spinal accessory nerve lesion
  • Electrodiagnostic: Nerve conductions
    • Medial antebrachial cutaneous sensory amplitude (SNAP): Small
    • Median motor: Small
    • Ulnar sensory amplitudes: Small; Exam may show normal or reduced Ulnar sensation
    • Normal: Median sensory amplitude
    • Rule out: Carpal tunnel syndrome
  • Treatment: Surgical
    • Sectioning of cervical band
    • Pain may improve after ~ 1 to 4 weeks
    • Little abnormality in strength or electrophysiology
  • Prognosis: Stabilizaton of weakness; ? Mild recovery
• Disputed Neurogenic
  • Thoracic outlet syndromes with no objective plexus change
  • Rib changes: None
  • Symptoms: Variable; Few objective
    • Pain & paresthesias: lower trunk distribution
    • Supraclavicular tenderness
    • Non-progressive
  • Treatment: Removal of anterior scalene muscle, ? benefit
• Droopy shoulder syndrome
  • Females
  • Low-set shoulders & Long necks
  • Pain & paresthesias
    • Upper neck, shoulder & head
    • Bilateral
    • Reduced by passive shoulder elevation
    • Increased by Plexus palpation & Downward arm traction
  • Electrodiagnostic: Normal
  • X-ray: 2nd thoracic vertebra visualized on laterals 2° sloping shoulders

Gunshot wounds

• Males; Average 28 years
• Location: Supraclavicular 23%; Infraclavicular 77%
• Plexus lesion
  • Usually left in anatomical continuity
  • Axonal degeneration
• Recovery: Variable; Some very good even with severe initial weakness

Neonatal brachial plexopathy⁷

• Incidence
  • 0.4 to 1 per 1,000 live births
  • Lower with Cesarian section
• Distribution

  ERB's PALSY From: P Bailey

  • Erb's Palsy (C5, C6 ± C7): 80% to 90%
  • Total plexus: 6% to 10%
  • Klumpke's palsy (C8 & T1): 1%
  • Diaphragm (Phrenic): 1% to 5%
  • Horner's: 5% to 30%
  • Right slightly more common than left
  • Bilateral: 10% to 20%
• Associated features
  • Fractures: Clavicle (10%); Humerus (10%)
  • Cervical spine subluxation or cord injury: 5% to 10%
  • Other nerve palsies
    • Facial palsy: 3% to 20%
  • Fetal
    • High birth weight (> 90th centile)
    • Prolonged delivery & fetal distress
    • Abnormal presentation: Breech; Shoulder dystocia (60%)
  • Increased risk of 2nd event with succeding births
  • No associated feature: 6%
• Prognosis
  • Spontaneous recovery
    • 50% at 6 months
    • ~ 90% of upper plexus palsies at 1 year
    • Less with extensive lesions
    • More with neurapraxia on nerve conduction studies
• Pathogenesis
  • Stretching brachial plexus by lateral traction
• Management
  • Prevent contractures
  • ?? Surgery in patients with poor recovery
• Variant
  • Prenatal weakness: 1 patient described

Heroin plexopathies

• Location: Brachial or Lumbosacral
• Onset: Pain; Allodynia
• Weakness: Proximal; Single extremity
• Course
  • Persistent proximal weakness
  • Pain resolution over months
• Associated disorders: Some patients with rhabdomyolysis
• Also see: Heroin toxicity

Pancoast syndrome

• Anatomy
  • Apical lung lesion
  • Primary lung tumor extension: Non–small cell carcinoma;
• Pain
  • Shoulder
    • Character: Burning or boring
    • Worse at night
    • Radiation: Along medial aspect of arm to elbow; Occasionally to the 4th and 5th digits
  • Interscapular: Involvement of posterior primary rami
• Signs: Later in course
  • Lower plexus distribution
  • Horner's: T1 involvement

Medial brachial fascial compartment syndrome

• Medial brachial fascial compartment: Anatomy
  • Extends from the clavicle to the elbow
  • Houses terminal nerves of brachial & plexus & axillary vessels
  • Formed by medial intermuscular septum
• Pathophysiology
  • Lesions within compartment: Hematomas; Aneurysms; Other masses
• Clinical
  • Pain, Paresthesias or weakness in distribution of affected nerves
  • Median nerve: Affected most commonly & severely
  • Other nerves in compartment: Musculocutaneous, Axillary, Radial & Ulnar
• Treatment: Early surgery

Primary Brachial Plexus Neoplasms

• Nerve sheath tumors, benign: Most common
  • Neoplasm features
    • Solitary schwannomas or neurofibromas
    • Involve upper or middle plexus, proximally
    • Slow-growing, encapsulated tumors
    • More commonly affect sensory roots
    • May grow through the neural foramen: Expand at both ends, dumbbell-shaped
  • Clinical
    • Onset
      • Painless mass
      • May have paresthesias exacerbated by motion or palpation
    • Motor symptoms: With ventral root or spinal cord compression
    • Treatment: Surgical; Recurrence uncommon
• Malignant nerve sheath tumors

HEREDITARY BRACHIAL PLEXOPATHIES: Autosomal dominant

HNPP: Recurrent; Painless HNA: Acute attacks; Pain HNA2: Chronic, Undulating; Pain HNA3: Acute attacks; Pain

HNA eyes: Hypotelorism

• Recurrent brachial neuropathy
• Painless
• Electrodiagnostic: Demyelination
• Prognosis: Recovery is common

• Genetics⁹
  • Mutations: R88W (Hotspot); S93F; -131G-C
  • Missense mutations are in N-terminus
  • Occasional non-penetrant individuals
  • Founder effect in some populations
  • Chromosomal aberration involving SEPT9/MSF
    • Therapy-related acute myeloid leukemia (t-AML)
    • Translocation t(11;17)(q23;q25) with MLL
• SEPT9 protein
  • Role in cell division
  • Forms filaments
  • Colocalizes with actin & tubulin
  • May localize to plasma membrane
  • 6 alterntively spliced forms
  • Nosology: MLL Septin-like fusion gene; MSF
• Onset: 1st (occasional congenital) to 3rd decades
• Neurological
  • Recurrent episodes
    • Over periods of years with intervening recovery
    • Average 6 to 8 years between eipsodes
    • Attacks
      • Associated with pregnancy & puerperum
      • ? After infections, surgery or stress
    • Few episodes after 50 years
    • Only rare patients with non-penetrance
  • Pain
    • Precedes weakness
    • Increased by limb movement
  • Weakness: Multifocal
    • Course: Maximum weakness from episode in days to weeks
    • May be bilateral: Clinical or sub-clinical denervation in opposite limb
    • Long thoracic nerve often involved: Scapular winging
    • Lumbosacral plexus also involved
    • Cranial nerves
      • Facial paresis
      • X: Hoarseness
      • VIII: Unilateral hearing loss
      • Horner's syndrome
    • Phrenic nerve paresis may occur
    • Right side more commonly affected than left
  • Tendon reflexes: Reduced
  • Sensory: Less prominent than weakness
• Morphological
  • Hypotelorism
  • Small face & palpebral fissures
  • Syndactyly
  • Short stature
• Electrodiagnostic
  • Axonal loss in affected limb: Small CMAP
  • Patchy denervation
  • Little evidence for generalized neuropathy
• Prognosis
  • Recovery (complete or partial) is common after each attack
  • Residual weakness after attacks
    • Little after initial episodes
    • Common: After several exacerbations
    • More weakness when Sensory changes are prominent

• Preceding event in 25%
• Onset
  • Painful muscles
  • Gradual: 6 weeks to 2 years leading up to 1st attack
• Course
  • Incomplete remissions
  • Persistent pain & weakness between episodes
• Lumbosacral plexus also involved: In separate events, or with brachial involvement

• Epidemiology: Finnish & Belgian families
• Clinical features
  • Onset
    • Bimodal: 1st or 5th decade
    • Pain & Weakness
  • Weakness: Acute attacks
    • Prodromes: Cold air; Strenuous exercise; Immobilization; Flu-like illness; Parturition
    • Distribution of weakness
      • Brachial plexus: Affected in all attacks
        • Unilateral or Bilateral
        • Whole plexus or Distal
      • Phrenic nerve
  • Pain
    • Frequency: Almost always present
    • Moderate to severe
    • Distribution: In limb with weakness
    • May occur without subsequent weakness
  • Sensory
    • Dysesthesias common
    • Loss: Distal, Hand
  • Course of episodes
    • Onset of weakness: Within hours after stimulus
    • Pain: Resolves over weeks
    • Weakness
      • May occur repetitively in same distribution
      • Resolves over weeks to months
      • Degree of resolution: Complete or Partial
    • Number of attacks
      • 0 to > 6
      • Asymptomatic carriers occur
      • One family with only one attack in afected members
    • Long asymptomatic intervals common
  • No dysmorphic features
• Electrophysiology
  • EMG: Denervation, Acute to chronic
  • Nerve conduction velocities: Normal

Proximal Lower Motor Neuron Arm Syndrome^1,2

• Nosology: Also called
  • Brachial Amyotrophic Diplegia
  • Flail arm syndrome
  • Vulpian-Bernhard syndrome
• Epidemiology
  • Onset age: Older; 45 to 76 years
  • Males (80% to 90%)
  • Sporadic
• Clinical
  • Onset: Upper extremities; Asymmetric
  • Weakness: Lower motor neuron
    • Asymmetric
    • Shoulder > Elbow
    • ± Bulbar change
    • Face & Legs: Spared for long periods
  • Fasciculations
  • Muscle atrophy
  • Tendon reflexes: Reduced in arms; Preserved in legs
  • Musculoskeletal: Subluxation of shoulder joints
  • Progression
    • To posterior neck & legs
    • Respiratory failure
    • Temporal progression
      • Slower than typical ALS
      • Over 2 to 11 years: 50% survival > 5 years
• Laboratory
  • ? Associated with anti-asialo-GM1 antibodies (10% to 20%)
  • Serum CK: Mildly elevated
  • Electrodiagnostic
    • EMG: Denervation & Reinnervation
    • NCV: Normal
  • Pathology
    • Spinal cord: Loss of Anterior horn cells; Astrogliosis
    • Motor cortex: ± Cell loss
    • Inclusions: Bunina, Lewy & skein-like bodies
• Differential diagnosis: Primary muscular atrophy (PMA)

LUMBOSACRAL PLEXOPATHIES

Circulatory   Arterial injections   Hemorrhage   Ischemic Diabetic Amyotrophy Differential diagnosis:   Cauda equina lesion   Hip disease   Episodic Hereditary   HNPP   Neuralgic amyotrophy Heroin Immune Infection Neoplastic Obstetric-Gynecologic Radiation Trauma

Psoas hematoma (arrow): CT scan

Lumbosacral plexopathy: Immune (vasculopathy)

• Onset: Late-age
• Clinical features
  • Sensory
    • Pain: Variable; Occasionally severe
    • Loss: Distal; Often asymmetric
  • Weakness
    • Asymmetric
    • Proximal, Distal or Both
    • Bilateral
  • Course: Progression over weeks to months
• Association: ? Diabetes
• Laboratory
  • EMG: Denervation in limbs & paraspinous muscles
  • Nerve biopsy
    • Inflammatory cells around small epineurial blood vessels
    • Differential fascicular loss of axons
  • High sed rate
• Prognosis
  • Recovery with treatment
  • Over months to years
• Treatment
  • Corticosteroids
  • ? IVIg

Lumbosacral plexopathy: Hemorrhage

• Compression (Diffuse) in psoas muscle
  • Weakness: Obturator & femoral nerve territory
  • Pain: Mild or none
  • Mass: None palpable
• Compression of femoral nerve in iliacus muscle
  • Pain
    • In groin or iliac fossa
    • Radiates to anteromedial thigh & medial lower leg
  • Weakness: Quadriceps
  • Sensory: Reduced in anteromedial thigh & saphenous distribution
  • Reflex loss: Knee
  • Mass: May be palpable in groin

Lumbosacral plexopathy: Intra-arterial injections

• Buttock injections
• Sciatic nerve ischemia: Vasospasm
• Plexus lesions
  • Onset: Minutes to hours after injection
  • Pain
  • Weakness: L-S plexus
• Injection of cis-platinum or fluorouracil into internal iliac artery
  • Painless lumbosacral plexopathy
• Other acute ischemic plexopathy: Surgery of aortic bifurcation & pelvic arteries

Lumbosacral plexopathy: Ischemic³

• Blood supply of lumbar & sacral plexus: Branches of the internal iliac artery
• Clinical: Symptoms & Signs mostly after exercise
  • Distribution: Unilateral or bilateral
  • Exercise provocation: Walking uphill; Riding a bicycle
  • Examination at rest often normal
  • Sensory
    • Pain: Gluteal region after exercise; 85%
    • Paresthesias
    • Loss: Pan-modal; Not dermatomal; Distal or Proximal
  • Weakness: Distal ± Proximal Leg
  • Tendon reflexes: May be reduced after exercise
• Electrodiagnostic: EMG & NCV often normal
• Pelvic arteriography
  • Bilateral stenoses of the internal iliac arteries (75%)
  • Other stenosis
    • Distal abdominal aorta + bilateral common iliac artery
    • Ipsilateral internal & common iliac artery
• Treatment: Percutaneous transluminal angioplasty; Stents

Lumbosacral plexopathy: Trauma

• Most 2° to double vertical fracture dislocations of pelvis
• Weakness: L5 & S1 distribution
• Prognosis: Poor recovery

Lumbosacral plexopathy: Obstetric-Gynecologic complications

• Footdrop
  • Associations
    • Protrated labor
    • Cephalopelvic disproportion
    • Midpelvic forceps delivery
  • Weakness: Foot dorsiflexion & eversion
  • Sensory loss: Lateral leg & dorsum of foot
  • Unilateral
  • Recovery: Frequent
• Femoral nerve ± Obtuator neuropathy
  • Bilateral in 25%
  • Associations
    • Lithotomy ± Vaginal delivery under anesthesia