Nerve Entrapments in Runners

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Nerve Entrapments in Runners

• Kevin deWeber, MD, FAAFP
• Military Sports Medicine Fellowship Director
• USUHS, Bethesda, MD

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Objectives

• Remind you of some of the anatomy facts you
  forgot over the years
• Remind you of the value of a meticulous history
  and examination
• Remind you of the incredible forces placed upon
  the body during running, and how nerves can be
  victims

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Neurological conditions cause 10-15 of
exercise-induced leg pain among runners.
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Common Nerve Entrapmentsin Runners

• Interdigital nerve (Mortons neuroma)
• First branch of Lateral Plantar Nerve
• Medial plantar nerve
• Tibial nerve
• Peroneal nerve
• Superficial
• Deep
• Sural nerve
• Saphenous nerve

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Anatomy of a Nerve

• Epineurium
• Perineurium
• Fascicles
• Axon
• Myelin sheath
• Tissue plane location
• Intermuscular
• Fibro-osseous tunnels
• Types of nerves
• Sensory
• Motor

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Pathophysiology of Entrapment

• Etiologies
• Isolated contusion
• Repetitive compression
• Stretch
• Surgical injury

• Patterns of injury
• Demyelination ? neurapraxia
• Axonal loss ? axonotmesis
• Transsection ? neurotmesis

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Symptoms of Nerve Entrapment

• Neuropathic pain
• Deep, aching
• Sometimes burning
• Often poorly localized
• Usually DISTAL to site of entrapment
• May affect only a portion of the distal nerve
• May radiate proximally (Villeix phenomenon)
• Often w/ tingling or cramping
• Numbness occasionally
• Symptoms worst during or after running

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Obtaining the History

• Pain questions- location, duration, type, etc.
• Presence and location of numbness and
  paresthesias
• Exertional fatigue and/or weakness
• Subjective muscle atrophy
• Symptom onset- insidious or post-traumatic
• Exacerbating activities

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History (continued)

• Changes in exercise duration, intensity or
  frequency
• New techniques or equipment
• Past medical history and review of systems
• Diabetes
• Hypercoaguable state
• Depression/anxiety
• Nutritional deficiencies
• Thyroid disease

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Important Exam Concepts

• Better anatomy knowledge ? more accurate
  diagnoses
• Examine along entire course of involved nerve
• Assessment of spine and nerve radicals
• Examination after provocative activities
• Post-running
• Consider consultation if you cant figure it out

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Local exam findings

• TTP over affected site
• Positive percussion sign (Tinels)
• Weakness of innervated musculature
• Numbness or hypoesthesia of innervated skin

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Expanded Exam

• Spinal ROM, tenderness and provocative tests
• Spurlings, Hoffmans, etc.
• Extremity ROM, tenderness, swelling, temperature
  changes, discoloration, sensation, pain with
  resisted movements

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Expanded Exam

• Anatomic malalignments
• Biomechanical abnormalities
• Provocative testing
• Post-exercise testing

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Differential Diagnosisof Nerve Entrapments

• CNS disease
• E.g. multiple sclerosis
• Radiculopathy
• Plexopathy
• Proximal neuropathy
• Polyneuropathy
• Myopathy

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Diagnostic Testing

• Radiographs exclude osseous lesions
• Osteophytes, tumors, arthritis
• MRI excellent soft tissue resolution
• Esp. peroneal neuropathies, tarsal tunnel
• Electrodiagnostic testing (EDT)
• Electromyography, nerve conduction velocity

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Electrodiagnostic Testing

• May be helpful but not always diagnostic even if
  a neuropathy present
• Testing at rest could produce a false negative
• Often 3 weeks of pathology required before
  EMG/NCS abnormalities can be detected
• An unrelated neuropathy may be detected
• Choose your specialist wisely- someone familiar
  with athletically-related neuropathies and
  someone who performs these on a frequent basis

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Treatment Principlesthe Rs

• Relative Rest
• Rehab exercise
• Relieve pressure/irritation
• Restore biomechanical abnormalities
• Referral to specialists if unsure of dx or
  condition refractory to tx

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Surgical Treatments

• Nerve decompression
• Neurolysis
• Neuroma excision
• Nerve resection
• Nerve repair
• Nerve or muscle transfer

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Specific Neuropathies
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Nerve Anatomy of Pelvis
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Lateral Femoral Cutaneous Nerve
EntrapmentMeralgia Paresthetica

• LFCN arises from L2-L3
• Exits pelvis medial to ASIS thru slit in inguinal
  ligament
• Injury usually at inguinal ligament
• Repetitive hip flex/ext
• Compression
• Etiologies
• Tight clothing/belts
• Rapid weight gain
• Dunlops Disease
• Thyroid dz or diabetes

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Lateral Femoral Cutaneous Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Neuropathic pain over anterolateral thigh

• Exam often normal
• ? Tinels 1 cm antero-inferior to ASIS
• ? Sensory deficit
• Injection can be diagnostic

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Lateral Femoral Cutaneous Nerve Entrapment

• TREATMENT

• deal with it
• Remove external pressure source
• Weight loss
• Clothing changes
• Injection
• Surgical decompression
• Neuromodulatory meds

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Neuromodulatory Meds

• Types of substances
• Tricyclic antidepressants
• Anti-seizure meds
• Mechanism of action
• Nerve transmission modulation
• ???

• Examples
• Amitriptyline
• Gabapentin (Neurontin)
• Pregabalin (Lyrica)

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Obturator Nerve Entrapment

• Exits pelvis in fibro-osseous tunnel (Obturator
  Canal)
• Innervates most adductors
• Sensation to ½ to 1/3 of distal medial thigh
• Entrapment commonly at exit of obturator canal

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Obturator Nerve Entrapment

• Symptoms

• Exam Test Findings

• Groin paindeep, achy
• Rare radiation, tingling, numbness

• Exam often unremarkable
• Diagnosis difficult
• EDT occasional fibrillation in adductor muscles
• Diagnostic injection useful

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Obturator Nerve Entrapment

• TREATMENT

• Guided injection
• Physical therapy to optimize hip ROM and strength
• Surgical ligation if refractory

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Nerve anatomy of thigh
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Nerve anatomy of lower leg
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Common Peroneal Nerve Entrapment

• Usually at fibular head
• Etiologies
• Compression Leg crossing, casts, orthoses
• Contusions
• Fibular head dislocation
• Tumors
• Tib-fit joint ganglion
• Bakers cyst
• Genu varum, recurvatum
• Compartment syndrome

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Common Peroneal Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Neuropathic pain in anterolateral leg, extending
  into dorsal foot and toe web spaces
• Weakness
• steppage gait
• foot slap
• Recurrent ankle sprains

• ?laxity of tib-fib joint
• ?Knee laxity
• Lateral
• Posterolateral rotatory
• ?Tumors
• Tinels after running
• Weakness of ankle eversion, dorsiflexion
• X-rays, MRI, EDT useful
• if refractory

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Common Peroneal Nerve Entrapment

• TREATMENT

• Peroneal ganglion cyst

• Neuromodulatory meds
• Address underlying cause
• Biomechanical aids to reduce nerve tension
• Dorsiflexion support
• Running style change
• Reduced varus recurvatum
• Injection
• Surgical decompression

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Superficial Peroneal Nerve Entrapment

• Most commonly entrapped at crural fascia
  penetration site
• Etiologies
• Muscular herniation
• Contusion
• Fibular fracture
• Edema
• Varicose veins
• Tight boots
• Tumors, ganglia

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Superficial Peroneal Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Diffuse ache over sinus tarsi, dorsal foot
• Numbness/tingling in 1/3
• ? Proximal radiation

• Fascial defect in 60
• ? Muscular herniation
• 10-13 cm above LM
• Provocative maneuvers
• pain over exit site during resisted ankle
  DF/Eversion
• Pain over exit site during passive ankle
  PF/Inversion
• ? Hypoesthesia
• X-rays, EDT usually normal
• MRI useful for mass lesions

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Superficial Peroneal Nerve Entrapment

• TREATMENT

• Similar to CPN entrapment
• Ankle stability rehab
• Injection at compression site
• Lateral wedge to decrease stretch
• Surgical decompression

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Deep Peroneal Nerve Entrapment

• Arises from CPN at fibular head
• Traverses inside anterior compartment
• Innervates TA, EHL, EDL
• Passes deep to Superior and Inferior Extensor
  Retinacula
• Common sites of compression
• Follows DP artery
• Innervates EDB muscle
• Sensation to 1st webspacde

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Deep Peroneal Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Deep aching dorsal midfoot pain
• Worse w/ pressure from shoes
• Etiologies
• Shoe pressure
• Contusions
• Osteophyte compression
• Edema
• Synovitis
• Ganglia

• Tinels
• Provoked w/ ankle DF or PF
• EDB weakness or atrophy subtle
• X-rays to reveal osteophytes or accessory
  ossicles
• Os intermetatarseum
• EDT may help localize
• MRI sometimes useful

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Deep Peroneal Nerve Entrapment

• TREATMENT

• Footwear changes
• Neuromodulatory meds
• Edema control
• Ankle stability rehab
• Injection
• Surgical decompression

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Sural Nerve Entrapment

• Formed by branches of TN CPN in posterior calf,
  11-20 cm proximal to LM
• Purely sensory distal posterolateral calf
  lateral ankle and midfoot
• Etiologies
• Recurrent ankle sprains
• Fractured cancaneus, 5th MT
• Achilles tendinopathy
• Ganglia
• Contusion
• Footwear pressure

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Sural Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Achy posterolateral calf pain
• Neuropathic pain in it distro

• Tinels, hypesthesia
• Provocation by ankle DF or inversion
• Diagnostic injection
• Consider imaging, EDT

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Sural Nerve Entrapment

• TREATMENT

• Reduce compression
• Achilles stretching
• Neuromodulatory meds
• Edema control
• Ankle stability rehab
• Surgical

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Saphenous Nerve Entrapment

• Purely sensory
• Branch to medial knee
• Medial calf
• Branch anterior to MM to medial midfoot
• Most vulnerable at medial knee
• Etiologies
• Adductor canal entrapment
• Pes anserine bursitis
• Contusion
• Post-surgical injury

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Saphenous Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Neuropathic pain medial knee, calf, midfoot
• No motor deficits

• ? Pes anserine bursitis, Tinels, hypoesthesia
• r/o femoral nerve lesions or L4 radiculopathy

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Saphenous Nerve Entrapment

• TREATMENT

• Address underlying causes
• Reduce compressions
• Therapeutic injection
• Surgical exploration decompression

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Nerve anatomy of foot
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Tibial Nerve EntrapmentTarsal Tunnel Syndrome

• 90 TN divides within flexor retinaculum
• Medial Plantar Nerve
• Lateral Plantar Nerve
• Medial Calcaneal Nerve
• Can involve TN, MPN, LPN, MCN variable
  presentations
• Etiologies
• Mass lesions (ganglia, tumors, venous stasis,
  tenosynovitis, os trigonum)
• Trauma
• Biomechanical compressions
• hyperpronation
• Systemic disease
• Idiopathic

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Tibial Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Neuropathic pain, tingling medial ankle, medial
  foot, and/or plantar foot
• 1/3 w/ Villeix phenomenon
• Hyperpronation running on banked surfaces
  exacerbates

• Inspection for foot deformities
• Palpate TT for masses
• Tinels
• Provocation w/ passive foot eversion, great toe
  DF
• ? Weak toe flexion
• X-rays to r/o ossicles
• MRI for mass lesions
• 88 of cases have lesions
• Use in refractory cases
• ? Labs to r/o DM, thyroid dz, rheum dz, anemia
• EDT usually abnormal

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Tibial Nerve Entrapment

• TREATMENT

• Activity modification
• Pronation control
• Intrinsic foot medial arch, and ankle stability
  strength exercise
• Achilles stretching
• NSAIDs, neuromod meds
• Injection
• Surgical decompression

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Interdigital (Mortons) Neuroma

• Interdigital nerves pass between MT heads, under
  inter-MT ligament
• Commonly 3rd webspace
• Etiologies
• High-heel shoes, demi pointe
• Tight footwear
• Hyperpronation
• MTPJ synovitis
• Irritation?neuroma

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Interdigital Neuroma

• SYMPTOMS

• EXAM TEST FINDINGS

• Neuropathic pain between 3/4th toes
• Worse running, standing, walking/ toe DF,
  squatting

• TTP involved inter-MT space
• Forefoot squeeze test
• Distal radiating pain
• ? Mulders click
• Biomechanical eval
• X-rays to r/o osseous dz
• Diagnostic injection
• MRI, EDT only to aid in DDx

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Interdigital Neuroma

• TREATMENT

• Activity modification
• NSAIDs
• Footwear changes (WIDER)
• Pronation control
• Great toe DF control
• MT pad at IMT space
• Steroid injection at IMT space
• Surgical neuroma excision

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Medial Plantar Nerve EntrapmentJoggers Foot

• Divides from TN
• Courses along FHL tendon
• Sensory medial sole plantar toes 1-3 ½
• Motor abductor hallucis, flexor hallucis brevis,
  FDB, 1st lumbrical
• Etiologies
• Footwear compression in the arch
• Valgus running
• Hyperpronation

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Medial Plantar Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Neuropathic pain in medial arch and plantar
  aspect of 1-3rd toes
• Medial sole paresthesias

• TTP at navicular tuberosity,
• Tinels
• Provocation w/ forced heel eversion
• ? AH hypertrophy
• Gait analysis ? Valgus running
• Diagnostic nerve block?

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Medial Plantar Nerve Entrapment

• TREATMENT

• Pronation control
• Medial arch strength
• Reduce valgus running
• Modify footwear/orthotics to reduce compression
• Injection
• Surgical release

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Medial Calcaneal Nerve Entrapment

• MCN pierces flexor retinaculum
• Sensation to posteromedial heel
• Etiologies
• Hyperpronation
• Footwear compression
• Repetitive heel impact

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Medial Calcaneal Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Neuropathic pain medial heel
• Worse w/ activity

• TTP, Tinels posterior to TN
• ? Tender, thickened nerve
• lamp cord sign
• X-rays or bone scan to r/o calcaneal stress
  fractures

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Medial Calcaneal Nerve Entrapment

• TREATMENT

• Pronation control
• Cut-out pads
• Footwear modification
• Injection
• Lamp cord sign surgical

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First Branch, Lateral Plantar Nerve Entrapment

• Relatively rare
• Arises from TN or LPN
• Pierces abductor hallucis muscle, courses
  inferiorly then laterally
• Innervates abductor digiti quinti, flexor
  digitorum brevis, quadratus plantae
• Originates just deep (superior) to plantar fascia
  origin
• Pressure from spurs in 20 of plantar fasciitis

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First Branch, Lateral Plantar Nerve Entrapment

• SYMPTOMS

• EXAM TEST FINDINGS

• Neuropathic medial heel pain
• Much like plantar fasciitis

• TTP medial heel superior to plantar fascia origin
• Uncommon Tinels
• ? Weakness of ADQ
• ? Lateral foot muscle atrophy
• Eval for fat pad syndrome, PF
• X-rays ? Spurs
• Consider MRI to r/o other conditions

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First Branch, Lateral Plantar Nerve Entrapment

• TREATMENT

• Activity modification
• NSAIDs
• Pronation control
• Heel cups
• Cushion shoes
• Achilles and PF stretching
• Neuromodulatory meds
• Steroid injection
• Surgical decompression

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Pearls From Experience

• These neuropathies often see you before you see
  them
• Have a high index of suspicion in patients that
  have seen multiple physicians without an
  improvement in symptoms
• REST is a 4-letter word, literally and
  figuratively, for athletes but can be curative in
  mild and early neuropathies

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Pearls From Experience

• Utilize post-exercise testing to improve the
  accuracy of your exam
• Restricting athletic involvement more imperative
  when weakness and atrophy are present, as opposed
  to sensory symptoms only
• Dont rely on imaging and nerve studies to make
  your diagnoses the history and physical exam are
  still your best tools with neuropathies

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Pearls From Experience
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Pearls From Experience

• Injection must be carefully placed, but can be
  both diagnostic and therapeutic

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Thanks!