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Marijuana for the Management of Proximal Myotonic Myopathy

      To the Editor:
      The debate on the legalization of marijuana for medicinal purposes continues in Canada and the United States. Marijuana has been reported to be effective in controlling nausea and vomiting associated with cancer chemotherapy and acquired immunodeficiency syndrome (AIDS), stimulating appetite, relieving symptoms of neurologic and movement disorders and glaucoma, and providing analgesia.
      • Marmor J.B.
      Medical marijuana.
      However, research on marijuana has been limited mainly because of the lack of access to a legal and controlled source, and there are concerns regarding the medical benefits versus risks and the potential for abuse.
      • Marmor J.B.
      Medical marijuana.
      • Gray C.
      Legalize use of marijuana for medical purposes, MDs and patients plead.
      • Joy J.E.
      • Watson S.J.
      • Benson J.A.
      The possible advantages of smoking marijuana include the rapid onset and the dissipation of symptoms and the ability to self-titrate, but long-term smoking is known to be damaging to the lungs.
      • Marmor J.B.
      Medical marijuana.
      • Adams I.B.
      • Martin B.R.
      Cannabis pharmacology and toxicology in animals and humans.
      Approved oral forms of marijuana with tetrahydrocannabinol (THC), the most active ingredient, are available but the pharmacokinetics of THC differ significantly from the smoked form.
      • Marmor J.B.
      Medical marijuana.
      These drugs lack specificity and produce many unpleasant side effects which limit their use.
      • Adams I.B.
      • Martin B.R.
      Cannabis pharmacology and toxicology in animals and humans.
      In the past decade new developments have increased our understanding of cannabinoids; the cellular mechanisms of action have been elucidated and a specific cannabinoid receptor has been identified and cloned.
      • Adams I.B.
      • Martin B.R.
      Cannabis pharmacology and toxicology in animals and humans.
      Recent reports indicate that cannabinoids not only inhibit nociception but also have a peripheral anti-inflammatory effect mediated by the CB1 receptor.
      • Richardson J.D.
      • Kilo S.
      • Hargreaves K.M.
      Cannabinoids reduce hyperalgesia and inflammation via interaction with peripheral CB1 receptors.
      However, the mechanisms by which cannabinoids produce analgesic effects are not fully known.

      Martin WJ. Basic Mechanisms of Cannabinoid-Induced Analgesia. IASP Newsletter;1999:3–6.

      Case Report

      We describe a 31-year-old man with proximal myotonic myopathy (PROMM), who experienced dramatic relief of muscle weakness and mild relief of dysesthesias with the use of marijuana. PROMM is an autosomal dominantly inherited multisystemic disorder. It is manifested by proximal weakness, myotonia, muscle pain, and cataracts, and may involve the brain causing mental changes such as hypersomnia and apathy.
      • Hund E.
      • Jansen O.
      • Koch M.C.
      • et al.
      Proximal myotonic myopathy with MRI white matter abnormalities of the brain.
      This young man had problems with muscle stiffening associated with almost all activities since the age of seven. Additionally, he experienced episodes of weakness in his muscles. Over the years, his lifestyle had been severely impaired by this disability and he had been unable to work.
      In recent years, the patient also suffered with several kinds of painful sensations. Firstly, he had pain in the upper extremities, which starts in the shoulders deep inside the muscles and can spread and radiate to the lower arms. It worsens with hot showers and inactivity, and improves with cool temperatures and movement, and can be as severe as 6/10 on a 0 to 10 scale. Secondly, since early teens, he experienced a sharp pain in his lower back over the sacroiliac joints, which radiates to the back of the hips, buttocks and down the thighs. This pain is induced by standing or walking too far and may be as high as 7/10. Thirdly, he had a very discomforting buzzing sensation all the time in the proximal muscles, mainly knees and thighs, described “as if electrical slugs were moving in and out of my muscles.” Additionally, he has extreme allodynia on the bottom of his feet and in the tips of his fingers, which is worsened with a hot shower or even by touching paper.
      The patient used marijuana in the past and reported rapid improvement in his symptoms. When he smoked 0.5 gm reefers, three to four times daily, he reported relief of muscle weakness but minimal improvement in pain. Nonopioid analgesics and adjuvant medications also were tried but proved ineffective and/or poorly tolerated.
      Previously, the patient tried the synthetic cannabinoid, nabilone (similar to dronabinol), in a dose of 1 mg three times daily in hopes it would have the same benefit on muscle function as marijuana. However, it was not effective for symptom control and gave “an unpleasant high feeling.”
      He agreed to undergo specific myometry testing to determine the efficacy of THC. Myometry is an instrument used to assess muscle weakness, and is a very efficient and accurate method to determine change in a patient's muscle strength.
      • Hyde S.A.
      • Goddard C.M.
      • Scott O.M.
      The myometer the development of a clinical tool.
      A physical examination and muscle testing in all four limbs was performed by the physiatrist after the patient had been off marijuana for six days. Myometry was also completed by a physical therapist on the same day, and the therapist was blinded to the results of the physiatrist. Strength was tested in mid-range isometrically to determine resistance level.
      These tests were repeated four days after marijuana was re-instituted, along with a “long-acting” opioid (hydromorphone 6 mg three times daily), and again two months later. The patient demonstrated improved function in all muscles and significant improvement in pain and stiffness. Myometry tests demonstrated increased muscle strength (Table 1, Table 2); Grade 5 strength was noted in all muscle groups in the lower extremities. Normal strength was achieved even in areas such as hip abductors bilaterally, and iliopsoas and hamstring on the left, where he was Grade 3 on initial testing. After muscle testing, he walked stiff-legged for about five steps and then resumed a normal gait. The physiatrist recommended that he continue his medications and exercise to maintain strength.
      Table 1Pounds Resistance (Manual)
      Before Treatment January 16After Treatment January 23After Treatment March 27
      Right gluteus medius7.932.736
      Rectus femoralis9.930.041.0
      Iliopsoas13.455.369.0
      Gluteus maximus12.743.048.0
      Quadriceps20.764.067.0
      Hamstrings10.750.763.0
      Ankle dorsi16.146.353.0
      Ankle evertors9.630.346.0
      Ankle invertors18.833.349.0
      Table 2Pounds Resistance (Manual)
      Before Treatment January 16After Treatment January 23After Treatment March 27
      Left gluteus medius10.530.034.0
      Rectus femoralis8.735.743.0
      Iliopsoas17.366.772.0
      Gluteus maximus10.526.760.0
      Quadriceps17.160.380.0
      Hamstrings7.142.752.0
      Ankle dorsi17.740.745.0
      Ankle evertors9.527.335.0
      Ankle invertors18.639.758.0
      During the first session prior to using marijuana, the physiotherapist reported that the patient had difficulty relaxing his muscles. He required a minimum of 60–90 seconds between repeated strength tests, and appeared to have significant difficulty in relaxing the agonist muscle after each strength test and would sometimes rub the muscle being tested. Due to rests required after each muscle test, the initial examination took approximately 75 minutes. During the second test session after using marijuana, the patient required significantly fewer rests and was able to do three maximal contractions in a row, with only one brief rest required on left iliopsoas testing.
      The issue now relates to the illegal use of marijuana and also the availability, purity and cost of this substance, reported at approximately $300.00 month. This patient is advocating for the legal use of marijuana for medical purposes to relieve his symptoms, thereby improving his quality of life.
      The controversy over the legal use of marijuana for medical purposes continues as concerns regarding its safety still exist. Nevertheless, its use is widespread. Approved oral forms of the active ingredient THC are available but these drugs lack specificity and may produce unpleasant side effects. Barriers to the legal supply of marijuana will have to be removed so that a standardized supply of the plant material is available for research. We need to further our understanding of the mechanisms of action of marijuana, determine the long-term benefits and risks of its use in specific medical problems, and develop alternative delivery routes because of the risks associated with smoking.

      Acknowledgements

      The authors would like to thank Rubin Feldman, MD, FRCPC and Anita Clarke, BScPT for their involvement and assistance with examinations and muscle testing.

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