1.
Entrapment Syndromes
of Lower Limb
Dr Zuber Ali Quazi
Senior Resident
Neurology

2.
Femoral Neuropathy
› Sites of compression:-
– Retroperitoneal space
– Deep to the Inguinal ligament.
› Etiology:-
– Sx (Abdominal; Pelvic; Hip)
– Sustained lithotomy position.
– Retroperitoneal haemorrhage.
– FA Catheterization.

3.
› C/F:-
– Knee Extension; Instability Knee.
– Hip flexion (Prox to Inguinal lig).
– Sensory loss - Anterior thigh; Leg.
– Pain – On Extension of thigh.
– Knee reflex.
› Edx:-
– NCV- Routine LL; Femoral n;
– EMG
› Quadriceps; Iiliopsoas.
› Adductor; PSM. (r/o Lumbar
radiculopathy; plexopathy)
Stimulation site:- Lateral to Femoral pulse,
below the inguinal ligament.
G1 Over Anterior thigh, halfway b/w inguinal
crease & knee,
G2 Over a bony prominence at knee.

4.
MERALGIA PARESTHETICA
Posterior to the
ASIS,
Across the iliac
crest
(4%)
Anterior to ASIS
and superficial to
the origin of the
sartorius muscle
(27%)
Medial to ASIS,
ensheathed in the
tendinous origin
of the sartorius
muscle (23%)
Medial to origin of
sartorius b/w
tendon of sartorius
& fascia of
iliopsoas muscle
deep to inguinal
ligament
(26%);
Most medial and
embedded in loose
connective tissue,
deep to the inguinal
ligament, overlying
thin fascia of iliopsoas
muscle (20%)

5.
Clinical features:-
› Painful, burning, numb patch of skin
over anterior and lateral thigh.
› Atrophy
› Weakness
› Loss of Reflex
› Etiology:-
– Prolonged standing
– Obese.
– Tight underwear
– Tight Pants, or belts.
– Car seatbelts
– Sx: Bone grafts, THR, Vascular bypass,
Hysterectomy, Cesarean section.
– Diabetes

6.
Diagnosis:-
Pelvic Compression
Test Downward,
compression force to
the pelvis and
maintains pressure
for 45 sec.
Resolution of
symptoms –Positive
Sp - 93.3%
Sn - 95%

7.
Diagnosis:- (contd..)
Neurodynamic testing:-
Step 1:- Examiner stabilizes the pelvis with the cranial hand and grasps
the lower extremity at the knee with the caudal hand.
Step 2:- The examiner then bends the knee and adducts the hip in
order to tension the LCNT.
Positive test = Reproduction of Symptoms.

8.
› Edx:-
– Routine LL study
– Lateral cutaneous nerve of the thigh sensory
study, (B/L studies).
– Stimulating just medial to the ASIS,
– Recording over Anterior thigh.
› Nerve Block Test:-
– 1% Lidocaine at the site where the LCNT exits
the pelvis at the inguinal ligament.
– Positive = If immediate symptom relief.
Diagnosis:- (contd..)

9.
Management:-
› Non‐Surgical Interventions
– NSAIDS
– Avoiding compression activities.
– RFA
– Nerve Block.
› Surgical Interventions
– LCNT neurolysis and resection
› KinesioTaping
› Acupuncture

10.
Piriformis Syndrome
› Definite diagnostic pts
(1) Sciatic neuropathy clinically,
(2) Edx e/o sciatic neuropathy,
(3) Surgical exploration showing entrapment
of the sciatic nerve within a hypertrophied
piriformis muscle,
(4) Subsequent improvement following
surgical decompression.
› C/f:-
– Pain more while sitting than standing;
– Worsening with Flexion, Adduction, IR.
– H/o trauma or
– Unusual body habitus –thin
– Tenderness in the mid-buttock that
reproduces the symptoms.

11.
Etiology:-
› Acute injury with the forceful internal rotation of the hip.
› Trauma to the hip or buttock area.
› Piriformis muscle hypertrophy:-
– Athletes.
– During periods of increased weightlifting.
› Sitting for prolonged periods:-
– Taxi drivers.
– Office workers
– Bicycle riders.
› Anatomic anomalies:
– Bipartite piriformis muscle.
– Course/branching variations with respect to the piriformis muscle.

12.
Clinical Examination:-
› Freiberg maneuver: pt lying supine, the examiner
forcefully internally rotates the leg, stretching the
piriformis.
› Pace maneuver: In sitting position, pt abducts the hip
against resistance, activating the piriformis.
› Beatty maneuver: Lying in lateral decubitus, pt abducts
the hip, activating the piriformis.
› FAIR (flexion, adduction, internal rotation) maneuver:
with the patient lying supine, the examiner passively flexes,
adducts, and internally rotates the hip, stretching the
piriformis.

13.
Diagnosis:-
› Edx:-
– Routine Peroneal & Tibial nerve motor study; Sural
sensory study.
– Superficial peroneal sensory study.
– H reflex latency b/w normal & FAIR positions of Hip.
› EMG:-
– At least TWO Peroneal nerve -innervated muscles
(TA, EHL, Peroneus longus)
– At least TWO Tibial nerve -innervated muscles
(Medial Gastrocnemius, TP, FDL)
– Short and Long heads of the Biceps Femoris
– At least ONE Superior Gluteal nerve -innervated
muscle (Gluteus Medius, Tensor Fascia Latae)
– At least ONE Inferior Gluteal nerve-innervated muscle
(Gluteus Maximus)
– L5 and S1 Paraspinal muscles
– At least TWO Nonsciatic, Non–L5–S1-innervated
muscles (Vastus Lateralis, Iliacus, Thigh Adductors) to
exclude a more widespread lesion
Stimulation site: Lateral calf
Recording site: b/w TA tendon & Lateral
malleolus.

14.
Management:-
› Short-term rest.
› Muscle relaxants.
› NSAIDs.
› Botulinum toxin.
› Surgery.

15.
Obturator Neuropathy
› Etiology:-
– Direct Trauma (e.g., Pelvic #)
– THR, Pelvic operations
– Compression from Tumor / Metastasis.
– Lithotomy position.
› C/F:-
– Pain, Sensory loss - Groin / Medial Thigh.
– Weakness - Adduction & IR.
Craig, A. (2013), Entrapment Neuropathies of the Lower Extremity. PM&R, 5: S31-S40.

16.
› NCV
› EMG
– Adductor grp.
– Femoral n. supplied grp.
– PSM

17.
Saphenous Neuropathy
› Etiology:-
– Procedures related to Femoral artery.
– Genu valgus & Internal tibial torsion.
– Knee arthroscopy & Meniscectomy
– Knee orthoses.
– Varicose vein stripping
› C/F:-
– Sensory loss.
– Neuropathic pain.
– Medial knee pain

18.
› D.D:-
–Femoral Neuropathy,
–L4 radiculopathy,
–Lumbar Plexopathy
Stimulation site;- Medial calf b/w Tibia & MG;
Recording sites:-B/w Medial Malleolus & TA
Mx:-
Conservative/ Symptomatic

19.
Fibular Tunnel syndrome
› DPN – Foot & Toe drop.
› SPN – Weak Foot eversion.
› Etiology:-
–Compression
–Casts
–Stockings
–Gardening; Farm work (squatting, kneeling)
–Mass lesions (Ganglion cysts, Tumors, Baker’s cyst)
–Miscellaneous (Weight loss, Habitual leg crossing)
–Iatrogenic – After Fibular osteotomies (2-27%);
TKR (0.3-1.3%);
Fortier LM et al. An Update on Peroneal Nerve Entrapment and Neuropathy. Orthopedic Reviews.2021;13(1).

20.
Diagnosis:-
› Edx:-
– Peroneal motor study,
› Recording: EDB
› Stimulating: Ankle, Below Fibular head and Lateral popliteal fossa.
– Tibial motor study.
– Superficial peroneal sensory study.
– Tibial and peroneal F responses.
› EMG:-
– At least TWO muscles by DPN – TA, EHL.
– At least TWO muscles by SPN – PL, PB.
– TP & at least ONE other by Tibial n.
– Short head BF.

21.
Superficial Peroneal Nerve Entrapment
› “Mononeuralgia in the Superficial
Peroneal Nerve”
› Etiology:-
–Sports.
–External compression - Tight
boots.
–Trauma - Fibular shaft #, Ankle
sprains a/w Ant. Talofibular lig.
tear- inversion injury
–Surgery – Fasciotomy, Varicose
vein surgery.
Rx of Ankle#
–Weight loss
Peroneus
Longus
Peroneus
Brevis
SPN
EDL

22.
› Burning pain- over the lateral calf and
dorsum of the foot
› ↑ Pf (eg Pressing the accelerator or
brake).

23.
› X-ray (To exclude stress fracture, Bone tumors)
› MRI of Leg / USG:- to identify muscle hernia
› Edx
D.D:-
• L5 radiculopathy,
• Ankle joint
pathology,
• Anterior
compartment
syndrome
Stimulation site:-Lateral calf;
Recording site:- B/W TA tendon & Lateral Malleolus.

24.
Management
› Avoid Tight boots, Ballet shoe ties
› Lateral shoe wedges.
› Local anesthetic and steroid.
› Cryoneuroablation.
› RFA
› Botulinum Toxin (20U).
› Surgery

25.
Tarsal Tunnel syndrome
Floor – Medial malleolus
Roof – Flexor retinalculum.
Content - Tibial nerve,
Tibial artery,
Tibial veins,
Tendons of the FHL, FDL, TP.
Compression of the Posterior Tibial nerve

26.
Etiology
› Extrinsic causes :-
–Trauma.
–Poorly fitting shoes
–Anatomic-biomechanical abnormalities (tarsal coalition,
valgus or varus hindfoot),
–Post-surgical scarring,
–Pedal edema, systemic inflammatory arthropathies.
› Intrinsic causes:-
–Tendinopathy, tenosynovitis, perineural fibrosis,
osteophytes, Hypertrophic retinaculum,
–Space-occupying lesions :- enlarged or varicose veins,
ganglion cyst, lipoma, neoplasm, and neuroma).
m.c.

27.
› C/f :-
– Perimalleolar pain.
– Burning pain in Ankle and Sole, ↑ Wt bearing; ↑Night.
– Paresthesias & sensory loss – Sole.
– Intrinsic foot muscle atrophy (Non-specific).
– Tinel sign ( non specific)
F>M
The Dorsiflexion-eversion test:-
Passively dorsiflexing and everting the
ankle to end range of motion and
holding for 10 seconds

28.
Recommended NCV protocol:-
› Routine studies
– Motor = Tibial, Peroneal.
– Sensory = Sural
– F response = Tibial, Peroneal.
– H reflex.
› Special studies
– Medial and Lateral Plantar Motor nerve studies.
– Medial and Lateral Plantar Sensory nerve studies
– Medial and Lateral Plantar mixed nerve studies.
Interpretation – By Comparing Latency and Amplitude on both sides

29.
Edx
AHB muscle:
G1 - 1 cm proximal and 1 cm inferior to navicular
prominence
G2 - metatarsal-phalangeal jt of the Great toe
Abductor digiti quinti pedis (ADQP) muscle:
G1 - Halfway b/w lateral sole of the foot and the lower
margin of the Lateral Malleolus.
G2 - Metatarsal-phalangeal jt of Little Toe
MEDIAL AND LATERAL PLANTAR MOTOR STUDIES
Stimulating the tibial nerve behind the medial malleolus.

30.
Edx (contd)
G1 - proximal and posterior to the medial malleolus
G2 - 3–4 cm proximally
Stimulation site:- proximally near the metatarsal-
phalangeal jt of the Great toe.
Stimulation site:- proximally near the metatarsal-
phalangeal jt of Little toe.
G1 - proximal and posterior to the medial malleolus
G2 - 3–4 cm proximally
MEDIAL AND LATERAL PLANTAR SENSORY STUDIES

31.
Edx
MEDIAL AND LATERAL PLANTAR MIXED NERVE STUDIES
Medial ankle:
G1 - Proximal & posterior to the Medial Malleolus
G2 placed 3–4 cm proximally
Medial sole is stimulated
Lateral sole is stimulated.
Recording site : Same as above

32.
Recommended EMG protocol:-
› AHB & ADQP (must be compared with the C/L side)
› At least TWO Distal Tibial-innervated muscles but prox. to
Tarsal Tunnel (MG, Soleus, TP, FDL)
› At least ONE Distal Peroneal-innervated muscle (TA, EHL)
Interpreting the EMG findings as Abnormal requires that:-
• The abnormalities be fairly marked
OR
• The contralateral asymptomatic muscle is distinctly
different on EMG from the symptomatic side.

33.
Differential Diagnosis
› Achilles tendonitis
› Compartment syndrome of the Deep flexor compartment
› Degenerative changes (calcaneal spurs, arthrosis of the joints of the
foot).
› Inflammatory conditions of the ligaments and fascia of the foot and
ankle.
› L5 and S1 nerve root compression
› Neurogenic intermittent claudication
› Plantar fasciitis
› Polyneuropathy
› Retrocalcaneal bursitis

34.
Management
› Ice over Tarsal tunnel. Analgesics, Gabanoids, TCA.
› Orthotic shoes-offloading the tarsal tunnel.
› Medial heel wedge.
› Night splints.
› Surgery (A positive Tinel sign)
Prognosis:-
Identifiable etiology; diagnosed early = Favorable.
Without an identifiable cause & who do not respond to conservative therapy =
Poor.
.

35.
Anterior Tarsal Tunnel Syndrome
› Etiology:-
– Trauma/Repetitive micro-trauma.
– Ganglion cyst.
– Osteophytes
– Hypertrophied EHB.
– Extrinsic- Tight-fitting shoes, Athletic
Gear
– Extreme Plantar flexion- Dancing,
soccer, diving.
– Traction injury - Ankle sprains.
– Ankle instability
› C/F:-
– Sharp shooting pain, Numbness/
Tingling.(1st web space)
DPN

36.
Management:-
› Change Footwear
› Rest.
› Topical Anti-inflammatory.
› Oral or topical NSAIDs/ Gabapentin.
› Perineural corticosteroid/anesthetic inj.
› Surgery

37.
Morton Neuroma
› Alt names:-
– Morton metatarsalgia
– Interdigital neuritis
– Morton entrapment
– Interdigital neuralgia
– Interdigital neuroma
– Interdigital nerve compression syndrome
– Intermetatarsal neuroma.
› Compressive neuropathy of the Interdigital nerve.
Transverse intermetatarsal ligament

38.
Etiology
› Narrow toe-box footwear,
› Hyperextension of the toes in high-heeled shoes,
› Inflammation of the intermetatarsal bursa,
› Thickening of the transverse metatarsal ligament,
› Forefoot trauma,
› High impact sporting activities,
› Metatarsophalangeal joint pathology,
› Lipoma.
F>>M
Middle aged.
U/L

39.
› C/F:-
– Plantar pain b/w Metatarsal heads
– ↑ walking; wearing tight-fitting, high-heeled shoes; ↓ Rest
– Burning, stabbing, or tingling with electric sensations.
– “walking on a stone or marble”.
– Numbness b/w toes (<50%).
– With prolonged walking, Radiates - Hindfoot or leg.
› “Mulder’s click.“
› Diagnosis:- USG, MRI (Dumbell shaped soft tissue lesion
within the intermetatarsal space. T1-↓; T2-variable).

40.
Management :-
› Wide, soft-soled, laced shoe with a low heel.
› Budin splint.
› NSAID, TCA, Gabapentin.
› RFA, Cryotherapy.
› Surgery.

41.
References:-
› Shapiro 4th edition; Electromyography and Neuromuscular
disorders.
› Craig, A. (2013), Entrapment Neuropathies of the Lower
Extremity. PM&R, 5: S31-S40.
› Fortier LM et al. An Update on Peroneal Nerve Entrapment
and Neuropathy. Orthopedic Reviews.2021;13(1).
› Hong CH et al. Tarsal tunnel syndrome caused by an
uncommon ossicle of the talus: A case report. Medicine
(Baltimore). 2018 Jun;97(25):e11008.
› Kiel J, Kaiser K. Tarsal Tunnel Syndrome: StatPearls. Treasure
Island (FL): StatPearls Publishing; 2022 Jan-.