The Nerve!

The Star (St. Lucia) - - HEALTH -

How do we move, make de­ci­sions, smell, feel pain and make mem­o­ries? The an­swer lies in our nerves, which make up the ner­vous sys­tem. The ner­vous sys­tem con­trols how we func­tion and re­act to our en­vi­ron­ment. It has two parts: the cen­tral ner­vous sys­tem (CNS) which con­sists of sen­sory nerves that mon­i­tor our in­ter­nal and ex­ter­nal con­di­tions by send­ing sig­nals to our brain for fur­ther pro­cess­ing and ac­tion; and the pe­riph­eral ner­vous sys­tem (PNS) which con­sists of mo­tor nerves that send sig­nals from our brain to our mus­cles and or­gans, help­ing us to func­tion and move within our en­vi­ron­ment.

Each nerve cell is di­vided into seg­ments called neu­rons which are sur­rounded by a sheath. The sheath acts as an in­su­la­tor and con­duc­tor

speed­ing up the move­ment of the sig­nal (ac­tion po­ten­tial). As the sig­nal moves from one neu­ron to an­other it changes from an elec­tri­cal im­pulse to a chem­i­cal and then back to elec­tri­cal im­pulse and can move at speeds of up to 120 me­tres per sec­ond.

When the sys­tem is at its op­ti­mum it works silently in the back­ground and we are not even aware of it. But it is a del­i­cate sys­tem and when things go wrong we can­not help but no­tice. So, what hap­pens when things do go wrong? Nerves are del­i­cate and can be dam­aged be­cause of an in­jury (ex­ter­nal), virus, dis­ease or con­di­tions. In the past we have dis­cussed dam­age to the nerves of the CNS re­sult­ing in con­di­tions such as Parkin­son’s, ALS, MS and stroke but now we are go­ing to dis­cuss dam­age to the PNS caused by ex­ter­nal in­juries. Pe­riph­eral nerve in­juries can be clas­si­fied into three groups:

• Nerves can be in­jured by be­ing over­stretched and even though nerves are elas­tic and strong force can cause a com­plete tear re­sult­ing in a to­tal loss of the sig­nal and paral­y­sis

• They can also be in­jured through a lac­er­a­tion and al­though it may cause tran­sec­tion most of­ten there is some con­ti­nu­ity.

• The third type of in­jury is a com­pres­sion in­jury (pinched nerve) where pres­sure causes dam­age but there is no tear. A com­mon com­pres­sion in­jury is known as Satur­day Night palsy, caused by rest­ing the arm over a chair and fall­ing asleep, putting pres­sure on the ra­dial nerve lead­ing to loss of move­ment and sen­sa­tion. De­pend­ing on the du­ra­tion of the com­pres­sion the symp­toms may be tem­po­rary with move­ment and sen­sa­tion re­turn­ing af­ter time but in some cases the symp­toms may be per­ma­nent.

Nerve dam­age may lead to neu­ri­tis—in­flam­ma­tion of the nerve that can be caused by an ex­ter­nal in­jury or sec­ondary to in­fec­tion or an un­der­ly­ing con­di­tion such as al­co­holism, can­cer, vi­ta­min B12 de­fi­ciency, vi­ta­min B6 ex­cess, di­a­betes, hy­pothy­roidism or ra­di­a­tion ther­apy. Nerve dam­age can af­fect one or both sides of the body re­sult­ing in weak­ness, numb­ness and burn­ing pain. Signs and symp­toms can vary de­pend­ing on the cause and area of symp­toms. The most com­mon signs are:

• Numb­ness or tin­gling in the arms or legs that can ra­di­ate into the hands and feet

• Burn­ing, throb­bing or sharp pain in a limb

• Chronic burn­ing pain and hy­per­sen­si­tiv­ity (causal­gia pain)

• Height­ened or low­ered sen­sa­tion to heat, cold and touch

• Poor co-or­di­na­tion and dif­fi­culty with fine mo­tor skills like do­ing up but­tons and pick­ing up small ob­jects

• Mus­cle weak­ness and in some cases paral­y­sis

• A tu­mour grow­ing around the nerve (neu­ro­ma­tous) Treat­ment not only fo­cuses on the cause but also on pain and func­tion. Not all nerve in­juries will re­cover, es­pe­cially where the symp­toms are caused by a de­gen­er­a­tive dis­ease or con­di­tion or com­plete dam­age to the nerve. Whether the symp­toms are tem­po­rary or per­ma­nent, pain may be an is­sue and in many cases pain med­i­ca­tion may be pre­scribed but phys­io­ther­apy can also help. A phys­io­ther­a­pist will use a range of modal­i­ties to help re­lieve pain, such as mas­sage, acupunc­ture and elec­trother­apy. Mus­cle weak­ness is also a symp­tom that needs at­ten­tion to pre­vent fur­ther dam­age to the nerve, the mus­cle and the joints. Where there is no move­ment at all then safe han­dling tech­niques will be taught and in cases where there is some move­ment then ex­er­cises will be given to strengthen the mus­cles. It is also im­por­tant to move the limbs through their nor­mal range of move­ment to pre­vent stiff­ness and short­en­ing of the mus­cles.

In cases where there is a chance of re­cov­ery, for ex­am­ple af­ter a lac­er­a­tion or even a stroke, then ex­er­cise alone may not be enough to im­prove func­tion. Re­learn­ing tasks and skills through sen­sory feed­back (touch, sight and sound) is im­por­tant as is per­form­ing tasks through nor­mal move­ment pat­terns. So, re­mem­ber what­ever you are do­ing there are thou­sands of im­pulses mov­ing through your body to make even the sim­plest of ac­tions pos­si­ble.

Kim Jackson is a UK-trained phys­io­ther­a­pist with over 20 years’ ex­pe­ri­ence. She spe­cialises in mus­cu­loskele­tal pain and dys­func­tion in­clud­ing back pain and sci­at­ica, stroke and other neuro con­di­tions plus sports phys­io­ther­apy, hav­ing worked with lo­cal, re­gional and in­ter­na­tional ath­letes and teams treat­ing in­juries and analysing biome­chan­ics to im­prove func­tion and per­for­mance. She is reg­is­tered with the Al­lied Health Coun­cil and is a mem­ber of PASL. She cur­rently works at Bay­side Ther­apy Ser­vices in Rodney Bay, O: 458 4409 or C: 284 5443; www.bayside­ther­a­py­ser­vices.com

The ner­vous sys­tem works seam­lessly in ev­ery­day body func­tions, so when some­thing does go wrong with a nerve, its hard not to miss.

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