ELECTROPHYSIOLOGICAL DIAGNOSIS OF CTS

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USEFULNESS OF THE MEDIAN TERMINAL LATENCY RATIO IN THE DIAGNOSIS OF CARPAL TUNNEL SYNDROME

VYOMA BUCH M. PTh-Neurology TOUCHEAL PHYSIOFITNESS & REHABILITATION CENTRE AHMEDABAD : 

VYOMA BUCH M. PTh-Neurology TOUCHEAL PHYSIOFITNESS & REHABILITATION CENTRE AHMEDABAD UNDER THE DIRECTION OF : DR. RUCHIR DIVATIA M.D.,D.M.- Neurology (Sri Chitra Institute, Trivandrum) Consultant Neurologist 12/18/2009 2

INTRODUCTION : 

INTRODUCTION Carpal tunnel syndrome (CTS) is a common condition, characterised by entrapment neuropathy of the median nerve at the wrist. (Journal of Orthopaedic Surgery 2003: 11(2): 190–193) CTS is commonly referred to electro diagnostic testing in clinical practice. There are patients with signs and symptoms suggestive of CTS but nevertheless remain difficult to diagnose using standard electro diagnostic techniques. (Muscle Nerve 1993; 16: 1366-73) To date, there have been few studies concerning the efficacy of the various techniques for measuring median motor conductions in the diagnosis of CTS. (Clinical Neurophysiology 120 (2009) 765-768) 12/18/2009 3

OBJECTIVES : 

OBJECTIVES To create a more sensitive electro diagnostic parameter for diagnosing CTS without adding any additional testing. (2) To compare the sensitivity of median terminal latency ratio to that of standard conduction techniques for diagnosing CTS. 12/18/2009 4

MATERIALS & METHOD : 

MATERIALS & METHOD MATERIALS : Nicolet EMG-NCV machine Electrodes Measure tape Micropore Marker Plinth Gel SUBJECTS : A retrospective study was done on 22 patients (36 hands) during a six months period with clinically suspected carpal tunnel syndrome and 30 volunteers (40 hands, consent taken) between the age of 25-65 yrs. NAME OF INSTITUTION : COMPREHENSIVE NEUROLOGY SERVICES SHREY HOSPITAL, AHMEDABAD. 12/18/2009 5

METHOD : 

METHOD INCLUSION CRITERIAS : Clinical symptoms and signs in median nerve distribution includes : - ◦ Numbness ◦ Tingling sensations ◦ Clumsiness or weakness ◦ Nocturnal awakening. ◦ Positive phalen’s test EXCLUSION CRITERIAS : Obvious muscle weakness or atrophy Fixed sensory impairment Other neuromuscular disorders 12/18/2009 6

METHOD : 

METHOD The study group patients were diagnosed with clinical CTS by neuro physicians. Explanation regarding type of sensations felt while performing NCV was given prior to the test. The standard conduction techniques performed were ◦ Median motor conduction study (stimulated from palm MTL-P, wrist MTL-W and elbow) ◦ Ulnar motor conduction study ◦ Median & Ulnar orthodromic sensory conduction. (Clinical Neurophysiology 120 (2009) 765-768) 12/18/2009 7

METHOD : 

METHOD MEDIAN NERVE STIMULATION (MOTOR NCV) 12/18/2009 8 AT PALM AT WRIST AT ELBOW

METHOD : 

METHOD ULNAR NERVE STIMULATION (MOTOR NCV) All the responses were supra maximal and the terminal latency differences between median and ulnar nerves were calculated. W-P MCV was calculated and the median terminal latency ratio was calculated as MTL-W divided by MTL-P. (Korean Neurology Association 2006;24:557-63) (Neurology 1999;53:1654-9) 12/18/2009 9 AT WRIST BELOW ELBOW

PROCEEDURE : 

PROCEEDURE ORTHODROMIC SCV MEDIAN NERVE ULNAR NERVE 12/18/2009 10

DATA ANALYSIS : 

DATA ANALYSIS In the study group, the sensitivity of each test was calculated as number of hands with a positive test and clinical CTS / number of hands with clinical CTS χ 100%. (Clinical Neurophysiology 120 (2009) 765-768) Amongst the study group of 22 patients (36 hands), 14 patients had both the hands examined and 8 patients had one hand examined. A screening history and physical examination done on control subjects consisted of 30 volunteers (40 hands), wherein 10 volunteers had both hands examined and rest 20 had one hand examined. The standard normal distribution is expressed in terms of mean and SD. (Clinical Neurophysiology 120 (2009) 765-768) 12/18/2009 11

RESULTSElectrophysiological Data of median nerve for 30 controls : 

RESULTSElectrophysiological Data of median nerve for 30 controls 12/18/2009 12

RESULTS : 

RESULTS 12/18/2009 13 MEAN VALUE OF BOTH THE GROUPS

BAR DIAGRAM OF MEAN : 

BAR DIAGRAM OF MEAN 12/18/2009 14

RESULTS : 

RESULTS 12/18/2009 15 COMPARISON OF SENSITIVITIES OF VARIOUS PARAMETERS IN CLINICALLY SUSPECTED CTS PATIENTS

PIE CHART OF SENSITIVITY : 

PIE CHART OF SENSITIVITY 12/18/2009 16

DEMOGRAPHIC DATA : 

DEMOGRAPHIC DATA 12/18/2009 17

DEMOGRAPHIC DATA : 

DEMOGRAPHIC DATA 12/18/2009 18

DISCUSSION : 

DISCUSSION Results indicate that median terminal latency ratio has highest sensitivity amongst other parameters taken into study. It is generally accepted that median sensory conductions are more sensitive than median motor conductions in the electro diagnosis of CTS. (Journal of Neurology Science 1994;127:221-9) Few studies have investigated the usefulness of motor studies; however which motor conduction technique is most valuable is not so clear. With the improvement in the stimulation technique, examination of short segment of the median nerve across carpal tunnel, is now considered a useful method. (Neurology 2002;58:1603-7, Muscle Nerve 2001;24:966-8) 12/18/2009 19

DISCUSSION : 

DISCUSSION Chang et al has reported that motor P-W conduction is more valuable than sensory P-W conduction for diagnosing CTS. (sensitivity of the test was 86.88%). Median terminal latency ratio is superior to P-W MCV as it avoids calculation errors. (Clinical Neurophysiology 120 (2009) 765-768) This study has allowed detection of 2 additional abnormal hands, which were normal according to standard conduction techniques. 12/18/2009 20

LIMITATIONS : 

LIMITATIONS Small sample size. Its a retrospective study. Duration of symptoms is not known. Further studies are needed to compare NCV study with other investigations like USG and imaging. 12/18/2009 21

CONCLUSION : 

CONCLUSION Median Terminal Latency Ratio of the wrist to palm requires a simple calculation from the existing method of electro diagnosis for CTS. Median Terminal Latency Ratio increases the diagnostic yield in CTS when other parameters remain normal. In this era of early diagnosis and early intervention, this study will benefit to all the physiotherapists exploring the field of electrophysiology. 12/18/2009 22

REFERENCES : 

REFERENCES T Ogura et al The relationship between nerve conduction study and clinical grading of carpal tunnel syndrome. Journal of Orthopaedic Surgery 2003: 11(2): 190–193 Uncini A et al Sensitivity of three median-to-ulnar comparative tests in diagnosis of mild carpal tunnel syndrome.Muscle nerve 1993;16:1366-73  Kyu-Yong Lee et al Usefulness of the median terminal latency ratio in the diagnosis of carpal tunnel syndrome Clinical Neurophysiology 120 (2009) 765-768 Bae JS et al Subclinical diabetic neuropathy with normal conventional nerve conduction study. Korean Neurology Association 2006;24:557-63. 12/18/2009 23

REFERENCES : 

REFERENCES Padua L et al Multiperspective assessment of carpal tunnel syndrome : a multicenter study. Italian CTS Study Group. Neurology 1999;53:1654-9 Kuntzer T Carpal tunnel syndrome in 100 patients : sensitivity, specificity of multi-neurophysiological proceedures and estimation of axonal loss of motor, sensory and sympathetic median nerve fibres. Journal of Neurology Science 1994;127:221-9 Chang MH et al Comparison of motor conduction techniques in the diagnosis of carpal tunnel syndrome. Neurology 2002;58:1603-7 Walters RJ et al Transcarpal motor conduction velocity in carpal tunnel syndrome. Muscle Nerve 2001;24:966-8 12/18/2009 24

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THANK YOU FOR YOUR ATTENTION 12/18/2009 25