Lower Limb Neuro
 

Power Assessment

 
 
Bookmark
On this page:MyotomesThe Motor Pathway

Overview

  • Power assessment is a key part of the motor examination, and can be used to identify focal or global weakness.

    • How to Perform

    • Ask the patient to move their hips, knees and ankles through each movement.
  • Start by asking the patient to move against resistance (5 / 4). If the patient cannot move against resistance, ask them to move the joint against gravity (3). If they still cannot move the joint, eliminate gravity (2). In the absence of signficant movement of the joint look for flicker movement (1 / 0). Grade as appropriate, comparing both sides.

    • Grading of Power

    • 0: no movement
    • 1: flicker of movement
    • 2 : movement without gravity
    • 3: movement against gravity
    • 4: against weak resistance
    • 5: normal power

    • Causes of Weakness

    • Upper Motor Neuron

    • Brain lesion - ischaemia, haemorrhage, tumour, trauma, encephalitis, vasculitis, demyelination
    • Spinal cord lesion - infarct, haemorrhage, abscess, transverse myelitis

    • Lower Motor Neuron

    • Nerve root pathology - trauma, radiculopathy, neoplasm
    • Brachial plexopathy - 
    • Focal peripheral nerve pathology - trauma, entrapment, focal ischaemia, sarcoidosis, tumour
    • Peripheral polyneuropathy - diabetic neuropathy, hypothyroidism, B12 deficiency, alcohol, paraneoplastic, Guillain-Barre, CIDP, Charcot-Marie-Tooth

    • Other

    • Neuromuscular pathology - myasthenia gravis, Lambert Eaton myaesthenic syndrome
    • Muscular pathology - muscular dystrophy, inflammatory myositis, paraneoplastic, thyroid disease, Cushing’s, statins, sarcoidosis
    • Poor compliance with examination

    • Interpretation

    • Weakness affecting an entire limb or entire side - likely due to central pathology
    • Weakness affecting a single myotome  - likely due to spinal nerve root pathology
    • Weakness affecting a single peripheral nerve distribution - likely due to a focal peripheral nerve palsy
    • Weakness affecting multiple peripheral nerve distributions - potentially due to a brachial plexus lesion
    • Generalised weakness - suggests a polyneuropathy, neuromuscular pathology or myopathy

Myotomes

  • Hip flexion: femoral nerve (L2-L4)Iliopsoas
  • Hip extension: sciatic nerve (L5/S1/S2)Biceps femoris, semitendinosus, semimembranosus
  • Hip adduction: obturator nerve (L2-L4)Adductor muscles, pectineus
  • Hip abduction: superior gluteal nerve (L4/L5/S1)Gluteus muscles
  • Knee flexion: sciatic nerve (L5/S1/S2)Bieps femoris, semitendinosus, semimembranosus
  • Knee extension: femoral nerve (L2-L4)Rectus femoris, vastus lateralis, intermedius & medialis
  • Ankle plantar flexion: tibial nerve (L5/S1)Gastrocnemius, soleus, peroneus muscles
  • Ankle dorsiflexion: deep peroneal nerve (L4)Tibialis anterior
  • Foot inversion: tibial nerve (L4/L5)Tibialis anterior & posterior
  • Foot eversion: peroneal nerve (L5/S1)Peroneus longus & brevis
  • Great toe extension: deep peroneal nerve (L5)Extensor hallucis longus, extensor digitorum longus

The Motor Pathway

  • Upper Motor Nucleus
    Primary motor cortex (precentral gyrus)
     
    Central Pathway
    Corticobulbar tract
    (via cerebral peduncle)
    Decussation
    Medullary Pyramids
    Spinal Pathway
    Lateral corticospinal tract
     
    Lower Motor Nucleus
    Ventral horn at the level of entry into the spinal cord
     
    Neuromuscular Junction
     
     
    Muscle
 
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Want more info like this?
  • Your electronic clinical medicine handbook
  • Guides to help pass your exams
  • Tools every medical student needs
  • Quick diagrams to have the answers, fast
  • Quizzes to test your knowledge
Explore
   
 
 

Read More...

 Azhary H, Farooq MU, Bhanushali M, Majid A, Kassab MY. Peripheral neuropathy: differential diagnosis and management. Am Fam Physician. 2010 Apr 1;81(7):887-92. Baima J, Krivickas L. Evaluation and treatment of peroneal neuropathy. Current reviews in musculoskeletal medicine. 2008 Jun 1;1(2):147-53. Benny BV, Nagpal AS, Singh P, Smuck M. Vascular causes of radiculopathy: a literature review. The spine journal. 2011 Jan 1;11(1):73-85. Biering-Sorensen F, Nielsen JB, Klinge K. Spasticity-assessment: a review. Spinal Cord. 2006;44:708-722. Boyraz I, Uysal H, Koc B, Sarman H. Clonus: definition, mechanism, treatment. Med Glas. 2015;12:19-26. Campbell WW. Evaluation and management of peripheral nerve injury. Clinical neurophysiology. 2008 Sep 1;119(9):1951-65. Fuller G. Focal peripheral neuropathies. Journal of Neurology, Neurosurgery & Psychiatry. 2003 Jun 1;74(suppl 2):ii20-4. Hoshino C, Koga D, Koyano G, Yamauchi Y, Sakai T, Okawa A, Jinno T. Femoral nerve palsy following primary total hip arthroplasty with the direct anterior approach. PloS one. 2019 May 20;14(5):e0217068. Johnston SC, Hauser SL. The beautiful and ethereal neurological exam: An appeal for research. Ann Neurol. 2011;70:A9-A10. Khare S, Seth D. Lhermitte's Sign: The current status. Annals of Indian Academy of Neurology. 2015 Apr;18(2):154. Khasnis A, Gokula RM. Romberg's test. J Postgrad Med. 2003;49:169.
Lee F, Lamont P, Powell A, Paul V, Stoyanov N. Cardiac Manifestations of Myotonic Dystrophy-Complexities in Diagnosis and Management. Heart, Lung and Circulation. 2017 Jan 1;26:S305.
 Lozsadi D. Myoclonus: a pragmatic approach. Practical Neurology [serial online]. August 2012;12(4):215-224. Menorca RM, Fussell TS, Elfar JC. Peripheral nerve trauma: mechanisms of injury and recovery. Hand clinics. 2013 Aug;29(3):317. Miller TM. Differential diagnosis of myotonic disorders. Muscle & nerve. 2008 Mar 1;37(3):293-9. Moore AE, Stringer MD. Iatrogenic femoral nerve injury: a systematic review. Surgical and Radiologic Anatomy. 2011 Oct 1;33(8):649-58. Nowak DD, Lee JK, Gelb DE, Poelstra KA, Ludwig SC. Central cord syndrome. JAAOS-Journal of the American Academy of Orthopaedic Surgeons. 2009 Dec 1;17(12):756-65. Pearce JMS. Dystonia. European Neurology. 2005; 53: 151-152. Plessen K. Tic disorders and Tourette's syndrome. European Child & Adolescent Psychiatry [serial online]. February 2, 2013;22:55-60. Reynolds J, Stavros K. Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP): clinical features, diagnosis, and current treatment strategies. Rhode Island Medical Journal. 2016 Dec 1;99(12):32. Robottom BJ, Factor SA, Weiner WJ. Movement Disorders Emergencies Part 2: Hyperkinetic Disorders. Arch Neurol. 2011;68:719-724. Rodriguez-Garcia PL, Rodriguez-Pupo L, Rodriguez-Garcia D. Clinical techniques for use in neurological physical examinations. I. General organisation, cranial and peripheral spinal nerves. Rev Neurol. 2004 Oct; 39(8): 757-66. Skogseid I. Dystonia--new advances in classification, genetics, pathophysiology and treatment. Acta Neurologica Scandinavica. Supplementum [serial online]. 2014;(198):13-19. Smaga S. Tremor. American Family Physician. 2003; 68:1545. Statland JM, Barohn RJ, McVey AL, Katz JS, Dimachkie MM. Patterns of weakness, classification of motor neuron disease, and clinical diagnosis of sporadic amyotrophic lateral sclerosis. Neurologic clinics. 2015 Nov 1;33(4):735-48. Stevens F, Weerkamp NJ, Cals JW. Foot drop. BMJ: British Medical Journal (Online). 2015 Apr 27;350.
Stewart JD. Foot drop: where, why and what to do?. Practical neurology. 2008 Jun 1;8(3):158-69.
 Suresh E, Wimalaratna S. Proximal myopathy: diagnostic approach and initial management. Postgraduate medical journal. 2013 Aug 1;89(1054):470-7. Tarsy D, Simon DK. Dystonia. The New England Journal of Medicine. 2006; 355: 818-829. Triplett JD, Robertson A, Yiannikas C. Compressive Lateral Femoral Cutaneous Neuropathy Secondary to Sartorius Muscle Fibrosis. JAMA neurology. 2019 Jan 1;76(1):109-10. Turner MR, Talbot K. Mimics and chameleons in motor neurone disease. Practical neurology. 2013 Jun 1;13(3):153-64. Valergakis FE. Cervical spondylosis: most common cause of position and vibratory sense loss. Geriatrics.1976; 31:51. Van Gijn J. The Babinski reflex. Postgrad Med J. 1995;71:645-648. Walker RH. Chorea. CONTINUUM: Lifelong Learning in Neurology. 2013;19:1242-1263. Walker RH. O.061 Choreas - phenomenology and differential diagnosis. Parkinsonism and Related Disorders. 2009;15:S16-S16. Webb CW. Mnemonic: Decorticate vs Decerebrate. Annals of Emergency Medicine. 1981 Jan; 10(1): 68. Wenninger S, Montagnese F, Schoser B. Core clinical phenotypes in myotonic dystrophies. Frontiers in neurology. 2018;9:303. Wild EJ, Tabrizi SJ. The differential diagnosis of chorea. Practical neurology. 2007;7:360-373. Wiles CM. Introducing neurological examination for medical undergraduates: how I do it. Pract Neurol. 2013 Feb; 13(1): 49-50.
Feedback