ACUTE PAIN THERAPY

Acute trauma is invariably associated with a degree of soft tissue injury rising swelling, hematoma, pain, reduced mobility and in the lower limbs impaired weight bearing. Sporting injuries and domestic accidents usually involve damage to muscles, joint ligaments and tendons. Examples include a sprained ankle or wrist or a twisted knee. More extensive soft tissue damage tends to result from industrial crush injuries or road traffic accidents. In the absence of bone fracture or other injury demanding priority treatment laser therapy should be instituted at the earliest opportunity. K-umar (3) reported a comparative study in 50 patients with inversion injuries of the ankle. He found that compared to conventional physiotherapy the laser treated patients showed a more rapid resolution of symptoms and an earlier return to full weight bearing. Patients were treated with a GaAlAs diode laser
(830n-m: 6OmW) at 48 hour intervals on a maximum of 3 occasions. A similar therapeutic regime has been described for whiplash injuries of the cervical spine (4). Ben Hatit and Lammens (5) used a defocused co laser to treat a variety of acute musculoskeletal -problems. The energy density varied between 40 70J/cm2. Patients were treated twice a week for up to 10 sessions. Pain was reduced by 70-90%.

Beneficial effects of laser therapy in acute small joint inflammation in rheumatoid arthritis has been described by Asada et al (6). Multiple joint irradiation using a GaAlAs diode (830nm: 6OmW) was applied for 15 seconds to each point. Pain was reduced by up to 66% together with an improvement in the measured range of movement (ROM).

In a similar report involving 938 patients with osteoarticular pain Soriano (7) found pain attenuation of 88% when treating a variety of acute conditions such as tenosynovitis, lumbago and cervical pain. He used a GaAs diode (940nm. pulsed 10,000 Hz: average power 40'mW) to treat patients twice weekly for a maximum of 10 sessions. The energy density delivered was 6-IOJ/cm2 per irradiated point.

Laser therapy has also proved helpful in reducing the severity and duration of postoperative pain. In a comparative study involving 20 patients undergoing elective choleecystectomy Moore et al (9) reported a 50 % reduction in postoperative pain experienced by the laser treated patients together with a concomitant reduction in analgesic requirements.

CHRONIC PAIN SYNDROMES

Chronic pain as the name implies, may last for months or years. Pain may arise as a result of damage caused by trauma or surgery or be manifest as a symptom of a system-dc disease process. In later life pain due to musculoskeletal "wear and tear" is very common. Finally neuralgic pain such as postherpetic or trigeminal neuralgia can cause prolonged problems to sufferers. A high percentage of patients referred for laser therapy will have already shown little or no response to conventional methods of treatment.

In rheumatoid arthritis (RA) laser therapy can benefit not only the pain of acute small joint inflammation but also the more established chronic pain of the disease. Gartner (9) in an excellent review article on rheumatology considered some 18 papers published over a 10-year period. All involved double blind trials of therapy with 5 having a crossover element. In considering the effect of laser therapy in chronic rheumatoid and associated musculoskeletal conditions all but one of the reports noted a significant improvement in pain. In his own work Gartner used a 904nm infrared laser to treat a variety of tendinopathies with a better than 80% success rate in relieving pain. He compared this to a similar rate of pain attenuation using anti inflammatory drugs (NSAIDS) but noted that whilst laser therapy was s free of side effect' some 20% of patients treated with NSAIDs suffering unacceptable side effects of medication. Asada and his colleagues' (10) in a further study of some 170 patients with rheumatoid arthritis used similar laser parameters and treatment protocols to their earlier reported work. The group achieved pain attenuation of up to 90% and improvement in ROM of up to 56%.

In a report of some 1000 treatments using a GaAlAs diode laser (830nm 60mw) for a wide variety of chronic pain syndromes Moore (11) noted an overall reduction in pain levels of some 70%.' Trelles et al (12) used a similar diode laser to treat 40 patients with degenerative joint disease of the knee. They delivered 18j/cm2 to each of 4 points round the knee twice a week for 8 weeks and reported a significant pain reduction in 82% with improved joint mobility. Li (13) used a 25mW-combined C02/HeNe laser to treat 90 patients with cervical spondylosis. Laser therapy was administered to a variety of acupuncture points for 10 minutes daily-for 2 periods each of 10 days with an intervening rest period of 10 days.' 90% of patients showed symptom improvement with an excellent result in 43%.

Fender and Di fee (14) reported an interesting trial involving patients suffering with chronic generalized musculoskeletal pain. They irradiated the stelf-ate ganglion using a HeNe laser with an initial exposure of 6 n-dnutes (36j/cm2) gradually increasing over 4-6 weeks to a maximum of 15 minutes (90j/cm2). They postulated a mechanism of reduced sympathetic irritability causing a stabilization of the response loop and a breaking of the pain cycle. In resistant cases they also treated segmental dermatomes and site specific trigger points.

Patients suffering from postherpetic neuralgia (PHN) have shown a good response to laser therapy. In a double blind crossover trial Moore et al (15) reported a mean reduction in pain levels of 74%. Patients were radiated with a GaAlAs diode (830nm: 6OmW) with the laser applied in contact mode to the centre of each 2cm2 grid over the affected are giving 24-30j/cm2 to each point. Treatment was given twice a week for 4 weeks. Using an identical treatment protocol but an extended regime of some 12 weeks Kemmotsu et al (16) reported an end of treatment pain attenuation of 89%. Otsuka and colleagues (17) used an 8.5mW HeNe scanner to treat the acute rash of herpes zoster. Once the skin rash had subsided treatment was continued using a CaAlAs laser (830nm: 6OmW). Within I month pain had been reduced by 76% with a final end treatment improvement of 97%. The early introduction of laser therapy produced a rapid resolution of acute herpes zoster rash and a reduced incidence of PHN.

LASER THERAPY IN POST HERPETIC NEURALGIA

Abstract

The first reports of the beneficial effects of Laser Therapy (LT) for Post Herpetic Neuralgia (PHN) were presented to the 6th Congress of the ISLMS in Jerusalem in 1985. Since there have been a number of papers published supporting the use of LT as the preferred primary modality of treatment for PHN. These papers are reviewed. Statistics are presented of some 300 patients suffering from PHN who were treated over a 9-year period. Full details of the treatment regime and protocol are given using a GaAlAs diode laser (830nm 6OmW) providing a contact power density of 3W/cm2. Results show that 85% of patients achieved a reduction in pain level (measured by self-assessment on a visual analogue scale) of greater than 50%. Patients suffering with cephalic pain (22%) achieved a lower level of pain relief (61%) and a higher recurrence rate (33%) following therapy than those with thoracic dermatome involvement (78% and 22% respectively). During a I year period of follow up less than 25% of all patients experienced pain recurrence. Retrospective analysis of results demonstrates a predictable pattern of clinical symptom relief during a course of therapy. An analysis of the costs involved in the treatment of PHN by conventional methods compared with LT shows that not only is LT more effective but some 28% less expensive. Recent reports suggest that use of LT in the acute phase of Herpes Zoster infection reduces the extent, duration and severity of the herpetic rash and greatly reduces the incidence of PHN.

Dr KEVIN C MOORE THE ROYAL OLDHAM HOSPITAL, OLDHAM, UK.

Presented to the British Medical Laser Association "241 " Workshop and A GM

The Royal London Hospital

April 1996