LOKÁLNA KONTRALATERÁLNA ANESTÉZIA PODĽA GROSSA - VLASTNÉ SKÚSENOSTI
J. Hančulák, FRO, Trenčianske
Teplice
Contralateral Local Anaesthesia
Therapeutic local anaesthesia in the treatment of chronic pain due to injury of the peripheral nervous system has long been utilized.Such pain is often accompanied by disturbances of the vasomotor system,muscle tone and local tissue health. In the healthy organism a functional symmetry as measured plethysmographically exists between the two sides of the body[6]. Acute disturbances lead to a hyperergic(plus) disturbance,chronic ones lead in general to a hypoergic one(minus disturbance). Suppression of the pain at its origin with a local anaesthetic restores the functional symmetry,eliminates the associated dysesthesia,dyskinesia and dyscrasia,and leads to euesthesia, eukinesia and eucrasia. Local anaesthesia at the potential origin of a peripheral irritation such as a scar or chronic inflammation already has been shown to be a useful therapeutic modality.
CLA - In the Treatment of Phantom Limb and Stump Pain
1.1 Nosology and definitions
Phanton limb syndromes are described after amputation of an extremity, more frequently after lower than after upper limb amputation. It is importatnt to understand the difernce, between several nervous disorders that may occur and co-exist following limb amputation :
- Phantom limb sensation is the perception of the continued of the amputated limb,it is not painful.
- Phantom limb pain describes painful sensationns perceived to originate from the amputated part of the limb.
- Stump pain corresponds to localized pain originating from the stump itself,usually related to local conditions/ischaemia,nevromas,necrotic scar.../,or myofascial pain, and frequently favoured by a bad and/or delayed adaptation to prosthesis.
1.2 Epidemiology and prevalence
Several recent studies have shown phantom limb pain /PLP/ to the present in up to 60 % of the amputees ? 60-85 %/.
1.3 Mechanism
Several theories exist for how PLP develops, incuding peripheral and central theories.
Peripheral mechanism could include, alone or associated:
-Nerve hyperexcitability and spontaneous firing of pain fibers,including neuromas as a source in 20 % of the patients or other irritative spines/abcesses,bone fragments.../
-Stump ischaemia and muscular spasms.
-Sympathetic nervous system dysfunction.
Central mechanism are also postulated in several hypothesis:
-Spinal cord functionnal plasticity with loss of inhibition and changes in WDR /wide-dynamic-range/ neurones.
-Central pattern-generating mechanisms, involving brain and spinal cord.
Despite it remains difficult to conclude from these various hypothesis, one could postulate that patients presenting with pain in a specific nerve territory are likely to have that nerve at source of PLP /with or without neuroma/,and that patients having PLP in the entire limb would be more likely to have pain from a central source.
1.4 Symptomatology
Various adjectives are employed by patients to describle PLP, more often burning, cramping, aching, lancinating or sometimes twisting, crushing, grinding, piersing like needles, squeezing, or even "knife-like" pain. Unnatural position of the amputated limb is also often reported. According to Sunderland
- Group I: mild, intermittent paresthesias; do not interfere with activity,work and sleeping .
- Group II: uncomfortable and annoying paresthesias;do not interfere with activity and sleeping.
- Group III: paresthesias of sufficient intensity and/or frequency and/or duration to be distresful;
intermittent interference with life-style.
- Group IV: Nearly constans severe pain; modifies sleping and normal activities.
1.5 Prevention
Adequate treatment of pre-and postoperative pain is suspected to be of major importance in the prevention of PLP.Neuroplasticity and functionnal changes at the spinal cord level/dorsal horn neurons/ may indeed play a role in long-term potentiation and related painful syndromes.In this framework,the role of regional anaesthetic techniques may be important,as blockade of nerve conduction by local anaesthetics have been shown to prevent central and peripheral mechanisms of senzibiliyation and,consequently,to prevent hyperalgesia,allodynia as well as autotonic lesions in animals.
1.6 Treatmens
GENERAL
The treatment of chronic pain following amputation is a difficukt task;with an unknown pathophysiology and aethiology it is not possible to give clear directives for pain treatment in amputees.The treatment of chronic pain in amputees-as in any other chronic pain condition-depends on the type of pain,its severity and ot what extent pain incapacoitates the patient.It is useful to distinguish between: /i/ preoperative pain persisting after amputations;/ii/ phantom pain;/iii/ stump pain.
Noninvasive techniques
Previous or currently used invasive and noninvasive treatment for stump/phantom pain.
Presumed method site of action Noninvasive Invasive
Periphery Nonnarcotic analgesis Neurectomy
Anticonvulsants Neuromectomy
Local anaesthetics Stump revision
Physiotherapy Rhizotomy
Guanethidine Ganglionectomy
Electrical stimulation Sympathectomy
Biofeedback
Spinal cord Narcotic analgesis DREZ lesion
Baclofen Dorsal column stimulation
Lidocain Chordotomy
Tricyclic antidepressants Epidural blockade
Calcitonin
Anticonvulsants
Peripheral electrical stimulation
Brain Narcotic analgesics Brain stem stimulation
Nonnarcotic analgesics Thalamic stimulation
Tricyclic antidepressants Brain stem lesions
Neuroleptics Thalamic lesions
Peripheral electrical Parietal lobectomy
stimulation Prefrontal lobotomy
'Placebo'
Psychotherapy Cingulectomy
DREZ= dorsal root entry-zone
DISCUSSION
a/ The patient is examined thoroughly from neurological,psychological,medical, orthopaedic and radiological aspects,and when necessary in cooperation with other medical disciplines.
b/ The patient is asked to indicate the focal points of his pain and to look for the corresponding points for his phantom and stump pain on the opposite side of the body. These points are usually distinctly hypersensitive.They are merked on the skin.
c/ The deep sensitivity of periosteum to pain is then examined by pressure of the finger and probe.
d/ Points within the hyperalgesic areas on the4 contralateral side which have the characteristic of lower resistance of the skin against a weak DC electrical current / 3 V / are identifield;marked and photographed.
e/ The hyperalgesic points are anaesthetised at the point of lower skin resistance with the finest needle possible/gauge 32/ and with very small dose of the local anaesthetic/o,2-1,oml,1% Mepivacain/ deep to the periosteum.
f/ The next day the results of the contralateral local anaesthesia are tested subjectively by the patient and objectively by testing the superficial hyperalgesia. Contralateral local anaesthesia is repeated daily as required by the patient's progress. Our results have encouraged us to try our contralateral local anaesthesia in other chronic pain condsitions,which will be reported elsewhere.An explanation for the therapeutic efficacy of contralateral local anaesthesia is not yet available:central inhibition is a strong possibility. It seems to be possible to influence both acuta and chronic pain affectively by manipulating the opposite side,when pain is seen after injuries of the nerve. This observation has also been made by acupuncturists/7/.However,our investigations did not lead us to believe that the hyperalgesic points on the phantom limb indicated by the patients corresponded to contralateral meridian points. We believe that the technique of contralateral local anaesthesia deserves further trial in patients with phantom limb and stump pain.