LETTERS TO THE EDITOR
SPONTANEOUS ELECTRICAL ACTIVITY AND MUSCLE BIOPSY ABNORMALITIES IN POLYMYOSITIS AND DERMATOMYOSITIS We concur with the findings of Streib, Miilbourn, and Mitsunioto' that fibrillation potentials (FPs) are most. frequently found in paraspinal muscles in patients with polymyositis or dermatomyositis or both, and we wish to eInpliasize that the degree of electrical and histologic abnormality may be greatest in these muscles as well. Over the past 18 months, we have evaluated 11 patients with a definite diagnosis of polymyositis or dermatomyositis, employing the criteria of Bohan et al.' Using techniques identical to those described by Streib et al, we performed needle electromyography (EMG) in at least seven muscles, including paraspinal muscles at multiple levels, in all patients. FPs were rated from 0 to 4+: 0 = no fihrillation; 1 + = persistent single trains in at least two areas; 2+ = moderate number in three or four areas; 3+ = many in all areas; and 4 + = filling the baseline in all areas. We demonstrated that FPs were found more frequently in paraspinal muscles at multiple levels than in any other muscle group; they were present in the paraspinal muscles in all 1 1 patient>. I n addition, FPs in paraspinal muscles were of a higher grade than those found in the most severely involved extremity muscles (p < 0.02, Wilcoxon test for correlated samples). One patient had EMG abnormalities confined to paraspinal muscles which demonstrated involvement at all levels examined; these abnormalities consisted of 2 + FPs, bizarre repetitive discharges, and voluntary motor unit action potentials (MUAPs) that subjectively were highly polyphasic and of short duration. Extremity muscle EMG-including quantitative measurement of MUAPs, as well as nerve conduction studies and tests of neuromuscular transmission-gave normal results. Biopsies were obtained from the biceps brachii and lumbar paraspinal muscles contralateral to the site of EMG; they demonstrated a characteristic inflammatory myopathy in the paraspinal muscle and only equivocal changes in the biceps brachii muscle. We agree that paraspinal muscle EMG should be considered in every patient with suspected myopathy. In addition, we feel that biopsy of paraspinal muscle should be considered in patients with suspected polymyositis
or dermatomyositis when EMG studies are normal 01equivocal in extremity muscles and abnormal in paraspinal muscles at multiple levels. We recognize that disorders other than myopathy can present with paraspinal EMG abnormalities. We make our suggestion only for patients with clinical and laboratory evidence of niyopathy without evidence of other disorders such as the polyradiculoneuropathy associated with diabetes mellitus or carcinomatosis that could explain the EMG abnormalities.
J. W. Albers, MD, PhD M. Mitz, MD A. R. Sulaiman, MBBS, FRCP(C) G. J. Chang, BS Department of Neurology and Physical Medicine and Rehabilitation The Medical College of Wisconsin The Milwaukee County Medical Complex Milwaukee, WI 53226.
1. Bohan A, Peter JB, Bowman RL, Pearson CM: A computerassisted analysis of 153 patients with polymyositis arid dermatomyositis. Medzn'ne (Baltimore) 56:255-286, 1977. 2. Streib EW, Wilbourn AJ, Mitsumoto 1%: Spontaneous electrical muscle fiber activity in polymyositis and dermatomyositis. Muscle &+ &%rue 2: 14- 18, 1979.
THE FLEXOR POLLlClS LONGUS DEEP TENDON REFLEX (FPL-DTR) Testing f o r the flexor pollicis longus deep tendon reflex (F'PL-DTK) can give very useful information about the presence or absence of the Kiloh-Nevin syndrome (anterior interosseous nerve entrapment) or of C,, spinal nerve root lesions. Recently, I reported seven patients with the Kiloh-Nevin syndrome; five had absent FPLDTR, which helped to confirm the diagnosis.' To test for the FPL-DTR, the brachioradialis reflex in the forearm is checked first; then the patient's hand is grahped gently, and the wrist is dorsiflexed, putting some tension on the flexor pollicis longus muscle (FPL). The musculotendinous junction of the muscle is then tapped lightly with the reflex hammer (fig. I), at which time the distal phalanx of the thumb smartly flexes. The musculotendinous junction of the FPL is easily found three fingerbreadths proximal to the na.vicular
MUSCLE & NERVE
Figure 1 Posltion for ekoting the flexor pol//cis longus deer, tendon ref/ex
tuberosity on the volar aspect of the patient’s wrist. If the muscle is not totally paralyzed, as sometimes can happen in the full Kiloh-Nevin syndrome, the bulky junction of the FYL I I ~ U S Cwith ~ ~ its tendon can be felt as the examiner compresses three fingers against the patient’s radius, while the patient alternately flexes and extends the distal phalanx of the thumb (fig. 2, DTR area 1). Sometimes it is necessary to reinforce the reflex by means of a modified Jendrassik maneuver, such as asking the patient to clench his teeth while the examiner taps the musculotendinous junction of the FPL. If the reflex is not found by tapping DTR area 1 (fig. 2 ) , then lightly tapping the shaft of the radius (DTR area 2 in fig. 2) wdl cause the thumb flexor to contract. T h e patient’s forearm should be fully supinated so that there is proper stretch on the thumb flexor. If the reflex cannot be obtained after the three maneuvers mentioned above, there must be interruption of the reflex pathways. Michael R. Rask, MD, FAANOS Sahara Rancho Medical Center 2320 Rancho Drive, Suite 108 Las Vegas, NV 89102
1. Rask MR: The Kiloh-Nevin Syndrome: report of seven cases. Clin Orthop, in press.
ORIGIN FLEXOR CARPI ULNARIS
ULTRASTRUCTUREOFNERVE BIOPSY I N WILSON DISEASE To date, only two cases have been reported in which the peripheral nerves of Wilson’s hepatolenticular degeneration have been examined by electron microscopy.’,2 We recently had the opportunity to study a third case.
FLEXOR OIGITORUM PROFUNDUS~
i a n
Figure 2. This schematic representation of the left forearm shows the musculotendinous junction of the flexor pollicis longus (FPL) at deep tendon reflex (DTR) area 7 . DTR area 2 is the shaft of the radius, where a light tap with the reflex hammer may elicit the FPL-DTR reflex. Note that the long thumb flexor is innervated solely by the anterior interosseous nerve ( A N ) .
MUSCLE & NERVE
A 16-year-old boy entered the hospital because of progressive psychomotor deterioration of t w o years’ duration. Neurologic examination disclosed severe dysarthria, widespread prominent muscular rigidity, and tonic hyperkinetic movements. There was no distinct sensory disturbance. Kayser-Fleischer rings were apparent on slit-lamp examination. Laboratory tests indicative of‘hepatic dysfunction were corroborated by laparoscopic and histologic evidence of cirrhosis of the liver. Hepatic copper concentration was 972 ,ug/g of wet tissue (normal, less than 250 ,ug/g). T h e 24-hour urinary copper excretion ranged between 800 ,us and 1,000 pgiday. Total serum copper levels were normal. T h e ceruloplasmin level was 11 mg/l00 ml of serum (normal range, 17-54 mg/lOO ml). A biopsy from the musculocutaneous nerve was performed. No obvious abnormality was apparent by light microscopy. By electron microscopy, many Schwann cells of myelinated axons were seen to contain pi granules. N o qualitative or quantitative abnormalities were found. DISCUSSION
In the case reported by Miyakawa et a1,2 the myelin of‘ some fibers was damaged, while the axons were well preserved and the unmyelinated nerve fibers were intact; these pathologic changes indicated primary demyelina-
have been attributed in the literature to changes in tion. In an intramuscular nerve, Anzil et all described translational efficiency. some modifications o f neurofilaments and neurotubules, with rare axonal degeneration. In o u r case, we saw Satyapriya Sarkar, PhD membrane-bound lamellar bodies in the cytoplasm of Department of Muscle Research Schwann cells of the myelinated nerve fibers. They looked Boston Biomedical Research Institute very much like pi granules, which have been seen in norand Department of Neurology mal peripheral nerves and in various n e ~ r o p a t h i e s . ~ ~ ~ Harvard Medical School Otherwise, there was no significant abnormality in the Boston, MA 021 14 nerve tissue of o u r patient, contrary to the reports of 1. Lodish HF: Translational control of protein synthesis. Annu Miyakawa et al’ and Anzil et a1.l &TI
J. M. Vallat, MD M. Dumas, MD Department of Neurology
Biochem 49:39-72, 1976.
2. Rogers PA, Jones GH, Faulkner JA: Protein synthesis in skeletal muscle following acute exhaustive exercise. i M u x l e E3 Nerue 2:250-256, 1979.
M. J. Leboutet, MD A. Loubet, MD Department of Pathology M. Vallat, MD Department of Ophthalmology HBpital Universitaire Dupuytren 87 031 Lirnoges, France
1 . Anzil AP, Herrlinger H, Blinzinger K, Heldrich A: Ultrastructure of brain and nerve biopsy tissue in Wilson disease. Arrh Neurol 31:94-100, 1974. 2. Mivakawa T, Murayama E, Sumiyoski S,Deshimaru M, Miyakawa T: A biopsy case of Wilson’s disease. Pathological changes in peripheral nerves. Acta Neuroputhol 24: 174- 177, 1973. 3. Thomas PK, Slatford J: Lamellar bodies in the cytoplasm of Schwann cells.] An& 98:691-692, 1964. 4. Tornonaga M, Sluga E: Zur Ultrastruktur der T granula. Acta Neuropathol 1556-69, 1970.
PROTEIN SYNTHESIS I N SKELETAL MUSCLE: A COMMENT T h e paper entitled “Protein Synthesis in Skeletal Muscle Following Acute Exhaustive Exercise,” by Rogers, Jones, and Faulkner,’ deals with the question of increased protein synthesis in skeletal muscle of untrained male guinea pigs that had been subjected to acute mechanical stress by treadmill run to exhaustion. T h e authors have shown that polysomes prepared from the hind limb of exercised animals incorporate 50% more radioactive leucine into protein than d o polysomes prepared from control muscles of nonexercised guinea pigs. I t was concluded that this increased amino acid incorporation reflects increased translational efficiency, since no quant.itative difference in the polysome profiles of exercised and control muscles was detected. While these results are quite interesting and support the currently accepted view that increased muscular activity increases the rate and extent of protein synthesis in muscle tissue, they do not necessarily prove that polysomes of exercised muscles have higher intrinsic translational efficiency. Only direct estimation of the mRNA contents of the isolated polysomes and total mRNAs from the exercised and control muscles can give a satisfactory explanation of the reported observations. Since mRNAs represent only about 1.5% to 2% of the total cellular RNAs, it is not surprising that the polysome profiles were very similar. It should also be pointed out that cell-free translation assays are notorious for yielding many artifactiial results which
A change i n the efficiency of translation is a reasonable explanation of o u r observation that polyribosomes isolated from muscles of exercised exhausted animals synthesized more protein per unit weight of RNA than those from rested controls! The magnitude of the difference and the reproducibility of the results make a translational artifact a n unlikely explanation. We agree that the results do not prove that polyribosomes of exercised muscle have higher intrinsic translational efficiency, b u t they are consistent with this premise a n d the experiments of others.’-j For example, the adrenocortical steroids have been shown to affect directly the initiation reaction of protein synthesis in m i ~ s c l e Echinoid .~ eggs increase their rate of protein synthesis manyfold, independent of ribosomal o r MRNA synthesis.’ A higher efficiency of ribosomes in the translation process has been reported in cardiac muscle after growth hormone treatment,2 and in developing chick skeletal ~ n u s c l e . ~ We note in o u r discussion that small changes in the RNA population could escape our analysis, a n d that such changes could provide a n alternative explanation for the results obtained! However, the references cited here a n d numerous others argue convincingly for the existence of other mechanisms that quantitatively modulate translational activity. Peter A. Rogers, BSc George H. Jones, PhD John A. Faulkner, PhD Department of Cellular and Molecular Biology University of Michigan Division of Biological Sciences Ann Arbor, MI 48109
1. Hille MB, Albers AA: Efficiency of protein synthesis after fertilization of sea urchin eggs.Nature 278:469-471, 1979. 2. Mowbray J, Davies JA, Bates DJ, Jones CJ: Growth hormone, cyclic nucleotides and rapid control of translation in heart muscle. Bioclzem J 152:583-592, 1975. 3. Nwagwu M, Nana M: Quantitative measurement of active polysomes of developing chick muscle. D m Biol 41:l- 13, 1974. 4. Rannels DE, Pegg AE, Rannels SR, Jefferson LS: Effects of starvation on initiation of protein synthesis in skeletal muscle and heart. Am J Physiol235:E126- 133, 1978. 5 . Rannels SR, Rannels DE, Pegg AE, Jefferson LS: Glucocorticoid effects on peptide-chain initiation in skeletal muscle and heart. Am JPhysiol 235:E134- 139, 1978. 6. Rogers PA, Jones GH, Faulkner JA: Protein synthetic activity in skeletal muscle following acute exhaustive exercisc. .bl?i.irIp 3 Ne!pnv, 2:250-256, 1979.
MUSCLE & NERVE