SUMMARY Percutaneous muscle biopsy is an important and acceptable technique in the study of conditions involving human skeletal muscle. A review of 436 conchotome and needle muscle biopsies obtained over 18 months in this centre is presented.Muscle biopsy is an important tool in the investigation of diseases of muscle, nervous system and connective tissues. The percutaneous techniques have clear advantages over open muscle biopsy, especially regarding the patient's comfort and the absence of unsightly scarring. Despite the small incision, however, specimens can be obtained of suitable size and quality to meet the majority of needs. There is now a large experience of needle muscle biopsy (fig la) in this country.1 2 It is recognised as a simple, rapid and repeatable method of obtaining muscle tissue, safely performed on an outpatient, and applicable to patients of all ages.3 We have recently adopted the technique of percutaneous biopsy using a conchotome4 (fig lb), an instrument primarily intended for nasal surgery, and already in use for muscle biopsy in Scandinavia.58 The conchotome adds further flexibility to investigation of muscle pathology, enabling biopsies to be taken from small muscles unsuitable for needle sampling. Both techniques are in routine use in our unit.In this article we outline our recent experience of percutaneous muscle biopsy, with particular reference to conchotome biopsy of the anterior tibial muscle, and we reinforce the case for percutaneous sampling over open muscle biopsy. PatientsThe age range of the 292 subjects (including 65 children aged 16 years or under) biopsied during the past 18 months was 8

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Since 1982, we have used X-ray computed tomography (CT) to study the skeletal muscles of neurological patients. We present here the findings in 23 patients with myogenic and 29 patients with neurogenic diseases. The method is convenient to demonstrate fat infiltration, atrophy and hypertrophy of skeletal muscles, but is of little help in differentiating between the 2 disease categories or individual diagnoses. The maximal isometric voluntary force of m. quadriceps femoris was measured in 13 of the patients with neurogenic, and in 10 of the patients with myogenic diseases. The power was compared with the cross-sectional area and the structural changes observed in the parenchyme of the muscles in the CT scans. A positive correlation was found between the size and the force of the muscle in both patient groups. The appearance of the muscular parenchyme was of little help to predict its function.

Primidone was compared to the unselective beta adrenoceptor antagonist propranolol in the suppression of essential tremor. In a 4-week single-blind placebo-controlled study primidone was given in increasing doses from 62.5 mg X 1 up to 250 mg X 3 daily and propranolol 20 mg X 3 daily. The drugs produced a similar reduction in the degree of tremor after 2 and 1 weeks' medication respectively. This indicates that primidone can be an alternative to propranolol when beta-blockers are contraindicated. However, primidone was significantly even more effective in the beginning after only 2 doses, when at the same time 10 of 13 patients showed a maximum of acute toxic side-effects producing nausea, vomiting, giddiness and/or sedation. Correlation analysis between the individual tremor amplitude reductions and plasma primidone concentrations showed on the second day a tendency towards a greater reduction in tremor in those patients with the highest primidone plasma concentration. By the fourteenth day tremor had increased compared with the second day and correlation analysis between individual increase in tremor amplitude and plasma phenobarbital concentrations showed the highest degree of tremor increase in those patients who had the highest levels of phenobarbital. These and other data suggest that after the first doses, tremor suppression and acute toxicity is related to the initial exposure to primidone and the plasma level of the drug itself rather than its metabolites phenobarbital and phenylethylmalanomide. The individual tremor frequency spectrums did not change significantly during the placebo and propranolol periods, whereas the frequency tended to decrease during the primidone period.