Post on 22-May-2020
Common Foot Neurological Conditions
Paul Strobel DPM
No relevant financial or nonfinancial relationships exist.
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Morton’s neuroma Pes Cavus (high arch foot) Tarsal Tunnel Syndrome Foot DropDiabetic Peripheral Neuropathy Charcot foot
Nerve related foot conditions
An entrapment of the plantar intermetatarsalnerve, most commonly between the 3,4 metatarsals, but may involve any intermetatarsal space.
Typically more painful with shoes as there is increased pressure on the nerve.
Patients complain of burning pain that often radiates to the toes, may describe a “rolled up sock” sensation in the forefoot.
Morton’s Neuroma
Morton’s Neuroma: exam
Mulder’s sign: Pain on palpation of the involved interspace with or without side‐to‐side pressure applied to the metatarsal heads.
MRI: may show if enlarged moderate/significantly.
Diagnostic injection.
Adequate fitting shoesMetatarsal/neuroma padsNSAID’s Corticosteroid injectionsNerve alcohol sclerosing injections Surgery to decompress or resect the nerve
Physical Therapy
Morton’s Neuroma: treatment
Morton’s Neuroma
Cavus foot can be linked to central and peripheral neurological diseases.
Ex: polio, Charcot‐Marie‐Tooth disease, Friedreich’s ataxia, cerebral palsy.
Up to 2/3 of patients with symptomatic cavus have an underlying neurological disorder. The most common is CMT.
Electromyography, NCV, sural nerve biopsy testing can help diagnose underlying causes.
Pes Cavus (High Arch) Foot
Pes Cavus (High Arch) Foot
Subtle cavus can be non‐neurological and is likely genetic.
Often biomechanically induced with plantarflexedfirst ray and hyperactive peroneus longus muscle.
Pes Cavus (High Arch) Foot
Difficult to manage due to rigid nature of the foot.
Patient’s typically overload the lateral column of the foot.
Common symptoms: ankle instability, peroneal tendonitis, lateral tibialstress syndrome, iliotibial band syndrome.
Orthotics: to help distribute pressures more evenly across the foot.
Foot and ankle bracing for neurological conditions.
Physical therapy to help reduce muscle imbalances.
Surgical intervention for instability, weakness, pain.
Cavus foot: treatment
Entrapment of the posterior tibial nerve or a branch in the tarsal canal by the flexor retinaculum, fibro‐osseous tunnels, or the deep fascia.
Tarsal Tunnel Syndrome
Tumor, cyst in the tarsal canal Fracture fragment of calcaneus pressing on the nerve
Severe flatfoot causing stretching of the nerve.
Enlarged blood vessels/varicose veins Generalized leg edema Metabolic causes: Diabetes
Tarsal Tunnel Syndrome: etiologies
Burning, stabbing, tingling at the bottom of the foot and inside of the ankle.
Pain to the tarsal tunnel increase with activity and relieved by rest.
Sensory loss in the plantar foot, medial ankle. Positive Tinel’s sign at tarsal tunnel. X‐ray for bony pathology, MRI for soft tissue pathology.
Nerve conduction studies.
Tarsal Tunnel: diagnosis
NSAID’s Localized steroid injection. Immobilization.Orthotics to control foot function. Physical therapy: iontophoresis.Gabepentin, Lyrica, Voltaren gel.
Tarsal Tunnel: conservative treatment
Removal of cyst, tumor, varicose vein in canal.
Decompression of the tarsal tunnel. (Similar idea as carpal tunnel release)
Tarsal Tunnel: surgical treatment
Weakness of ankle dorsiflexion from deep peroneal nerve compromise.
Physical findings may include: difficulty clearing the foot during swing phase of gait (toes dragging or catching on the floor), foot slap, paresthesia's with distribution of common peroneal nerve.
Foot Drop
1. Radiculopathy L4/L5 – disc herniation or foraminal stenosis.2. Common peroneal neuropathy:
‐external compression; bed rails, below knee cast, trauma‐rapid weight loss‐traction during knee surgery, ‐‐inversion/plantarflexion ankle injury
3. UMN causes: CVA, ALS, MS, brain tumor, spinal cord injury.
4. Micronutrient deficiency: (Vitamin B 12 post bariatric surgery)
Foot Drop: etiologies
Neurological exam: motor strength testing, reflexes. Nerve conduction, EMG testing. Lab studies for metabolic or toxic causes if no trauma or obvious cause. BS, Hemoglobin A1c, ESR, CRP, BUN, Vit. B12, creatinine.
Imaging: x‐rays to evaluate for fracture tibia/fibula, MRI to evaluate for bone injury, brain/spine injury, nerve root impingement.
Foot Drop: diagnosis
Foot Drop: treatment
Bracing with AFO (Ankle Foot Orthotic), help dorsiflexion during swing phase of gait and provide stability.
Medications: antidepressants (amitriptyline, gabapentin, lyrica), oral and topical NSAID’s
Nerve blocks. Functional Electrical
Stimulation: may help if bracing does not fit or work.
Team approach is useful: physical medicine rehabilitation, podiatry, interventional spine, orthotist/prosthetist, physical therapist.
Surgery: (if conservative treatment fails) Decompression of fibular nerve, sciatic nerve, nerve
root, spinal cord, brain tumor. Foot and ankle arthrodesis near ankle joint, tendon
transfers. Repair of nerve or tendon injury if traumatic cause.
Foot Drop: treatment
Most common form of neuropathy in the developed world.
Found in about 25% of diabetics. Distal symmetric polyneuropathy – stocking‐glove pattern in hands and feet.
Factors involved: poor glycemic control, duration of diabetes, hyperlipidemia, elevated albumin, obesity.
Diabetic Peripheral Neuropathy
Medications: Lyrica, cymbalta, gabapentin, amitriptyline.
Topicals: lidocaine patches, capsaicin cream.
TENs unit. Treatment can help reduce symptoms and progression.
Diabetic Peripheral Neuropathy: treatment
• Patient role: Control diabetes and blood sugars.Adequate nutrition. Control Vitamin deficiency: Vit. B1,B6,B12
Maintain a healthy weight.
Diabetic Peripheral Neuropathy
Patient’s at risk of foot and ankle ulceration because they cannot feel pain or sore areas.
Runners and walkers need to have cushioned well fitting shoes.
Encourage daily foot checks for problems. Be seen urgently if any problems are noted to help reduce chance of infection or amputation.
Diabetic Peripheral Neuropathy
Charcot neuroarthropathy: unilateral redness and swelling of a lower extremity.
Foot/ankle bones begin to soften, fracture, displace. “bag of bones”
Due to coexisting peripheral neuropathy most patient’s do not have pain.
Can occur with other peripheral neurology etiologies: ex: alcoholic or metabolic.
Charcot Foot
0.1‐5% of patients with peripheral neuropathy will develop Charcot arthopathy.
Onset usually after average of 15 years of Diabetes Mellitus history.
50‐60 years of age
Charcot Foot
2 main theories: (likely a combination) Neurovascular: vascular damage to autonomic nervous system causes reflex hyperemia and increase in blood flow to the limbs. (Washes out the bones)
Neurotraumatic: microtrauma initiates an inflammatory cascade leading to breakdown.
Charcot foot: etiology
Physical exam: warm, red, swollen foot. Increased temperature from contralateral foot.
Imaging: Bone scan, MRI, X‐ray. In presence of open wounds, infection can be very difficult to differentiate.
May need bone biopsy, cultures. Be cautious in diabetic neuropathic patient having unilateral foot and ankle swelling and/or fractures without history of trauma.
Charcot foot: diagnosis
Medications: biguanides and bisphosphonates, intranasal calcitonin.
Immobilization foot and ankle: CAM boot, Total contact or below knee cast with non weight bearing.
Bones can take 3‐6 months to begin to stabilize and a full year to heal.
Once temperature reduces and bones begin to stabilize then CROW boot and long term a diabetic shoe.
Charcot foot: treatment
If foot and ankle become a rocker bottom type foot or are unstable then surgical intervention may be needed. Surgical arthrodesis of foot and ankle. Removal of bone spur.
Significant risk of ulcerations, infections leading to amputation.
Charcot foot: treatment
Charcot Foot reconstruction
Outcomes following excision of Morton's interdigital neuroma: a prospective study. Bucknall V, Rutherford D, MacDonald D, Shalaby H, McKinley J, Breusch SJ. Bone Joint J. 2016 Oct;98‐B(10):1376‐1381. PMID:27694592 Corticosteroid injection for Morton's neuroma with or without ultrasound guidance: a randomised
controlled trial. Mahadevan D, Attwal M, Bhatt R, Bhatia M. Bone Joint J. 2016 Apr;98‐B(4):498‐503. doi: 10.1302/0301‐620X.98B4.36880. PMID:27037432 Minimally invasive endoscopic decompression of the intermatatarsal nerve for Morton's neuroma. Kubota M, Ohno R, Ishijima M, Hanyu R, Sakai K, Sugawara Y, Ochi H, Mukasa H, Kaneko K. J Orthop. 2014 Jan 31;12(Suppl 1):S101‐4. doi: 10.1016/j.jor.2014.01.004. PMID:26719604 Evaluating the Cavus Foot. Eleswarapu AS, Yamini B, Bielski RJ. Pediatr Ann. 2016 Jun 1;45(6):e218‐22. doi: 10.3928/00904481‐20160426‐01. PMID:27294497
References
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References cont.
Foot Drop: Looking Beyond Common Peroneal Nerve Palsy: A Neurophysiology Centre Experience. Yap SM, McNamara B. Ir Med J. 2016 Apr 11;109(4):388. PMID:27685482
A prospective study of midfoot osteotomy combined with adjacent joint sparing internal fixation in treatment of rigid pes cavus deformity (PDF Download Available). Available from: https://www.researchgate.net/publication/262884005_A_prospective_study_of_midfoot_osteotomy_combined_with_adjacent_joint_sparing_internal_fixation_in_treatment_of_rigid_pes_cavus_deformity [accessed Jan 4, 2017]
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