Introduction to Electrodiagnosis PDF

Dr. Dany Alphonse Anwar Habib Lecturer of physical therapy for neuromuscular disorders and its surgery MUST University Introduction to Electrodiagnosis Mission and Vision of the College of Physical Therapy – Misr University for Science and...

Dr. Dany Alphonse Anwar Habib Lecturer of physical therapy for neuromuscular disorders and its surgery MUST University Introduction to Electrodiagnosis Mission and Vision of the College of Physical Therapy – Misr University for Science and Technology (MUST) Intended Learning Outcomes of the Course (ILOs) A- Knowledge and Understanding A1:Discuss the theories and principles, and updates in advanced electrodiagnosis and related sciences A2: Explain electrophysiological concepts required to perform electromyography and nerve conduction studies. B- Intellectual Skills B1: Demonstrate basic science of anatomy and physiology of connective tissue, bone, joint and muscle with clinical care of patients. B3: Examine electrical activity of muscles and nerves. B6: Fill in the diagnostic section of electrophysiologic testing in the patient evaluation sheet. Intended Learning Outcomes of the Course (ILOs) - continued C- Professional &Practical skills: C1: Demonstrate basic clinical reasoning and problem-solving abilities, and sound rationales underlying physical therapy role, client diagnosis/prognosis. D- General and transferable skills: D1: Use technology in obtaining up to date information regarding neurorehabilitation techniques. D3: Express thoughts and ideas effectively verbally and using written forms in various languages. Required Reading: pp: 1,2,5-7  By the end of this lecture, the student should have a brief idea about Electrodiagnosis tests and its usage.  Topics will be discussed in this lecture: 1- Electrodiagnosis different studies. 2- Electrodiagnostic device components. 3- Types of electrodes 4- Uses of electrodiagnostic studies 5- Cardinal rules of nerve conduction studies and electromyography Electrodiagnostic (EDX) studies play a key role in the evaluation of patients with neuromuscular disorders.  studies are included: 1- nerve conduction studies (NCSs), 2- repetitive nerve stimulation, 3- late responses, 4- blink reflexes, 5- and needle electromyography (EMG), in addition to a variety of other specialized examinations. NCSs and needle EMG form the core of the EDX study.  Electrodes 1- Stimulating electrodes A- cathode B- anode 2- recording electrodes A- active (pickup) electrode; B- reference electrode 3. ground electrode—filters out background noise Specific types of electrodes for NCV studies are: 1- sensory ring electrodes  Specific types of electrodes for NCV studies are: 2. stimulation probes with anode and cathode electrode tips Specific types of electrodes for NCV studies are: 3. bar electrodes Specific types of electrodes for NCV studies are: 4. disc electrodes  ground electrode  EDX studies yield critical information about: - the underlying neuromuscular disorder - and allow use of other laboratory tests in an appropriate and efficient manner. - Likewise, the information gained from EDX studies often leads to specific medical or surgical therapy.  Accordingly, a directed neurologic examination should always be performed before EDX studies in order to identify key clinical abnormalities and establish a differential diagnosis.  NCSs and EMG are most often used to diagnose disorders of the peripheral nervous system. These include disorders affecting the - primary motor neurons (anterior horn cells) - primary sensory neurons (dorsal root ganglia) - nerve roots - brachial and lumbosacral plexuses - peripheral nerves - neuromuscular junctions - And muscles. - Disorder arises in the central nervous system (e.g., tremor or upper motor neuron weakness). Exact etiology cannot be defined based on EDX studies alone. CARDINAL RULES OF NERVE CONDUCTION STUDIES AND ELECTROMYOGRAPHY  1- NCSs and EMG are an extension of the clinical examination. NCSs and EMG cannot be performed without a good clinical examination. 2- When in doubt, always think about technical factors. Accurate NCSs and EMG depend on - Intact equipment (e.g., EMG machine, electrodes, and stimulator), - as well as correct performance of the study by the electromyographer. *type I errors (i.e., diagnosing an abnormality when none is present), *type II errors (i.e., failing to recognize an abnormality when one is present). If there is an unexpected abnormal EDX finding that does not fit the clinical examination, the lack of a clinical–electrophysiologic correlation should suggest a technical problem. Case… if a routine sural nerve sensory conduction study shows an absent potential but the patient has a normal sensory examination of the lateral foot (i.e., sural territory), one should suspect a technical problem (e.g., improper electrode placement or too low stimulus intensity).  3- When in doubt, reexamine the patient. Case… In the example given, if the sural sensory response is absent after all possible technical factors have been corrected, the clinician should reexamine the patient. If the patient has clear loss of vibration at the ankles, there is less concern about an absent sural sensory response. If the patient’s sensory examination is normal on reexamination, the absent sensory response does not fit the clinical findings, and technical factors should be investigated further.  4- EDX findings should be reported in the context of the clinical symptoms and the referring diagnosis. 5- When in doubt, do not overcall a diagnosis. Because electrophysiologic tests are very sensitive, mild, subclinical, and sometimes clinically insignificant findings often appear on EDX testing (minor abnormalities should not be deemed relevant unless they correlate with other electrophysiologic findings and, most importantly, with the clinical history and Examination).  6- Always think about the clinical–electrophysiologic correlation. This rule combines all of the earlier rules. One usually can be certain of a diagnosis when the clinical findings, NCSs, and EMG abnormalities all correlate well.