Year 2 MBChB Clinical Skills Session Examination of the Sensory System

Transcription

1 Year 2 MBChB Clinical Skills Sessin Examinatin f the Sensry System Reviewed & ratified by: Dr D Smith Cnsultant Neurlgist Dr R Davies Cnsultant Neurlgist Dr B Michael Neurlgy Clinical Lecturer Dr J Williamsn Neurlgy Registrar Dr A Clarke GP Aug 2018

2 Sensry Examinatin Learning bjectives T knw the basic anatmy and functin f the sensry system T be able t understand and carry ut a bed side assessment f the sensry system and assess crdinatin T adhere t waste dispsal plicies including sharps and clinical waste The sensry system Sensry infrmatin is detected at the peripheral receptrs, travels via peripheral nerves, nerve rts, spinal crd, brainstem and thalamus t sensry crtex. There are 2 pathways, spinthalamic tract and psterir (r drsal) clumn. Pain, light tuch and Temperature sensatin are carried by small unmyelinated fibres in the spinthalamic tract. This decussates (crsses ver) immediately in the spinal crd Vibratin and Prpriceptin (jint psitin) are carried by large myelinated fibres in the Psterir (r drsal) clumns. They ascend n the same side f spinal crd and crss ver in the brain stem. Indicatins fr sensry examinatin The fllwing list f ptential indicatins is by n means exhaustive, a patient may present with; Paralysis r changes in sensatin Unexplained muscle weakness Strke Trauma spinal crd injury r direct brain injury Autimmune disease / metablic disease (Lyssmal strage disease, rare) Cngenital cnditins Diabetes Spinal crd sectin

3 Nrmal sensry examinatin Nrmal sensatin allws a patient t detect; pain (pinprick), light tuch and temperature in whichever area is tested, vibratin at tips f fingers and tes and prpriceptin (jint psitin) (i.e. small amplitude mvements) at distal jints A sensry examinatin is nt rutinely perfrmed but is nly dne with certain clinical presentatins i.e. when the patient cmplains f altered sensatin r when the patient has impaired balance Sensry pathway Lcalisatin f prblems can be determined by knwledge f the area f skin supplied by peripheral nerves, sensry dermatmes, decussatin f spinthalamic tract and drsal clumns. Dermatnes A dermatme is an area f skin supplied by a single spinal nerve fr the mdalities f sensatin. Knwledge f the dermatmes can help t lcalise prblems invlving the spinal crd r nerves. Please nte the dermatme brders will differ frm ne text bk t anther as indeed they d frm ne individual t anther. It is nt an exact sceience.

4 Dermatmes f the upper limb C5 C3 C4 T2 C5 C6 T1 C6 C8 Dermatmes f the lwer limb L1 L2 S5 S4 S L3 L4 L5 S1 C7 S2

5 Dermatmes f the trunk V1 V2 V3 C2 C3 C4 T2 T5 T10 Anther example f dermatmal distributin

6 Patient Safety In clinical practice Encurage the patient t describe the distributin f altered sensatin. Initially demnstrate the test chsen t assess sensatin in an area f skin the patient perceives t be nrmal and test that sensatin within the area reprted t be abnrmal. Map the extent f altered sensatin by asking the patient t cnfirm that the sensatin demnstrated i.e. light tuch, feels the same n the area f cncern. Then decide if this area relates t/ r is assciated with a spinal, dermatmal r peripheral /cutaneus nerve pattern f altered sensatin. Testing light tuch Use fingertip / cttn wl r a mnfilament (usually fund in diabetic clinics) Ask the patient t respnd when stimulus is detected and cnfirm that it feels the same as the test site. Dab the skin and then withdraw the stimulus - d nt drag, strke r tickle as this stimulates the hairs n the skin Cmpare ne side with the ther

7 Pain - sharp Use a dispsable neurtip, r an unflded paper clip D NOT use a hypdermic needle Explain and demnstrate the stimulus with the sharp n an unaffected area Then g directly t the area, which the persn perceives t be abnrmal and map ut the distributin f the abnrmality. This shuld then be recrded as impaired cutaneus perceptin t pinprick in e.g. a stcking distributin bilaterally. Always dispse f sharp safely Testing vibratin sense With a 128 Hz tuning frk create vibratin by either taping it gently against yur hand r by pushing the prngs twards ne anther. Wait fr the audible sund t disappear befre placing n the patient. Demnstrate n a bny prminence away frm the affected area (frehead r sternum fr example). T avid reducing the vibratin hld at the rund thumb rest just under the frk, the flat rest at the base is held against the patient. Place the base f 128 Hz tuning frk n the mst distal pint f the limb being tested i.e. tip f a finger r te. Any finger r te may be tested as it makes n difference. (In chsing a te, it is easier t use a larger te fr the practicality f testing) Ask the patient Can yu feel that?. If they cannt, mve prximally, testing vibratin sense at bny prminences (radial stylid prcess, lecrann etc) until the vibratin is detected. If the patient s vibratin sense is abnrmal recrd as absent belw.

8 Tes Testing prpriceptin Hld the patient s fingertip between yur fre finger and thumb, ensuring yu hld the sides f the finger. Avid hlding frm abve and belw as the patient may sense up and dwnwards pressure, therefre giving false results. Demnstrate what yu are ging t d by mving their fingertip up and dwn whilst they watch. T test prpriceptin, ask the patient t clse their eyes. Repeat the mvements mving the fingertip randmly up r dwn in small incremental mvements and ask the patient t cnfirm what directin their finger has been mved in. If the patient cannt detect small amplitude mvements, r makes errrs, increase the amplitude f mvement. If the patient cannt detect larger amplitude mvements, test prpriceptin at a mre prximal jint. If the jint psitin sense is abnrmal it is recrded fr example as absent belw ankle bilaterally r, if milder, errrs f at the great tes bilaterally. Prpriceptin rder f testing Upper limb Distal interphalangeal jint Prximal interphalangeal jint, Metcarpphalangeal jint Wrist Elbw shulder Lwer limb Interphalangeal jint f the hallux, Metatarsphalangeal jint, Ankle Knee Hip Remember prpriceptive sense tends t decline with age;

9 Rmberg s test The patient shuld stand with their feet 6 inches apart, arms by their sides and eyes clsed, the patient shuld then cunt t 10. The examiner shuld stand behind r beside the patient with arms arund but nt tuching them. If prpriceptin is intact balance is maintained. This is a negative Rmberg's test. If prpriceptin is knwn t be lst, d nt perfrm this test Patterns f sensry lss As with mtr examinatin, the pattern f sensry lss helps t lcalise a lesin t specific parts f the nervus system. The initial distinctin is whether the lesin is in the central r peripheral nervus system. A gd way f achieving this is t recgnise patterns f sensry lss caused by spinal crd lesins (central) peripheral neurpathy (peripheral) Spinal crd lesin With a spinal crd lesin sensatin is lst r altered belw the level f the lesin, this is called a sensry level. The extent f the lesin determines whether the lss f sensatin is uni- r bi-lateral Familiarise with the crss-sectins f the crd and sites f where the main tracts decussate (crss ver), this will enable yu t understand the detail f the pattern f sensry lss. Peripheral neurpathy Lss, r altered, sensatin starts at the end f the lngest nerves; i.e. in the tes and spreads prximally The fingers are affected after the tes/feet This prduces a glve and stcking pattern f sensry lss The type f nerve fibre affected (myelinated, unmyelinated r bth) determines which mdalities are lst. Further Reading