of Radiology,15 (1992) 230-238 B.V. All rights reserved. 0720-048X/92/$05.00

European Journat

230

0 1992 Elsevier Science Publishers

EURRAD 00321

Imaging techniques in myotonic dystrophy. A comparative study of ultrasound, computed tomography and magnetic resonance imaging of skeletal muscles* H. Schedel”,

C.D. Reimersb,

M. Nggele”, Th. N. Witt”, D.E. Pongratz b and Th. Vogl”

aDepartment of Radiology, Universitv of Munich. b Friedrich Baur-Institute, University of Munich, and ‘Department Grojhadern”,

of Neurology, “‘Klinikum

University of Munich, Germany

(Received 27 January 1992; accepted after revision 14 June 1992)

Key words: Muscle, ultrasound;

Muscle, CT; Muscle, MRI; Muscle, disease; Muscle, comparative

study; myotonic dystrophy

Abstract Limb and trunk muscles of 57 patients with the juvenile or adult form of myotonic dystrophy were studied by imaging techniques (ultrasound, computed tomography, magnetic resonance imaging). Typical findings were atrophy of the tibialis anterior and triceps brachii muscles and fatty degeneration of the vastus intermedius, sartorius, tibialis anterior and soleus muscles as well as of medial head of the gastrocnemius muscle. Magnetic resonance imaging was the most sensitive technique in depicting mesenchymal muscle alterations, followed by computed tomography and ultrasound. The data support that imaging is more sensitive in detecting the myopathy than measurement of the creatine kinase activity.

Introduction Ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) have proved helpful in the diagnostic work-up of muscle disorders. They are primarily applied for determining the distribution and degree of muscle atrophy and mesenchymal alterations, for directing muscle biopsy and electromyography [ 11. However, although these new techniques are increasingly used in myologic diagnostic procedures there are few comparative studies available in literature [ 2,3 1. Ultrasound, CT and MRI findings of muscles in myotonic dystrophy were retrospectively studied. This autosomal dominant inherited disease is the most frequent adult-onset muscular dystrophy [4]. It is characterized by myotonia, muscle wasting of facio-cervicodistal distribution, cataract, mental, endocrine, and

Correspondence to: Dr. C. D. Reimers, Friedrich-Baur-Institut bei der Neurologischen und Medizinischen Klinik, Klinikum Innenstadt, Ludwig Maximilian+Universitat, Ziemssenstr. la, D-8000 Munchen 2, Germany. * Supported by the Friedrich-Baur-Stiftung, Munich.

cardiac abnormalities and frontal baldness. Systematic studies on ultrasound and MRI of skeletal muscles in this disease are missed in the literature. The purpose of the study was to describe typical findings of the imaging techniques in myotonic dystrophy and to compare the three imaging techniques with regard to their sensitivity and the sensitivity of measuring the creatine kinase activity in the serum. Patients and methods Patients Thirty-three female and 23 male subsequent patients, aged 15 to 76 years (median age 38.8 years), suffering from the juvenile (n = 5) or adult (n = 52) type of myotonic dystrophy were examined between January 1986 and February 1991. All patients exhibited a degenerative myopathy on clinical and/or myopathological examination as well as a myotonia on clinical and/or electromyographic examination. Forty-nine patients showed weakness of facial or temporal muscles, and 49 presented with weakness of the limb and trunk muscles. A cataract was seen in

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37 patients, 12 had no cataract and 8 patients did not undergo an ophthalmological examination. Eighteen male patients exhibited frontal baldness; 20 patients demonstrated obvious mental abnormalities such as emotional disturbances or deterioration of intelligence. Informed consent for the examinations was obtained from all patients.

TABLE

Grading of muscle strength

Tibiahs anterior” Brachioradiahs” Biceps brachii” Peroneus longusb Rectus abdominis” Triceps brachii” Soleusa Sartori& Pronator tere? Vastus medialis” Lumbar erector truncia Brachialis” Supinator” Vastus lateralis” Rectus femoris” Vastus intermedius” Semitendinosus” Gastrocnemi& Deltoideus”

The scale for muscle grading recommended by Wieck [ 51 was used: 0 - complete paresis, 1 - contraction palpable or visible, but no movement of the muscle, 2 - ability to move with gravity lessened, 3 - movement against gravity, 4 - holding against minimum pressure, 5 - holding against moderate pressure, 6 - normal muscle power. Muscle biopsies

Open muscle biopsies were obtained in 43 patients. In 14 patients a muscle biopsy was not performed because the diagnosis was certain on clinical and electromyographic grounds, such as muscle weakness of facie-cervico-distal distribution, myotonia and cataract, or because of histopathologically proven myotonic dystrophy in family members. The specimens were processed according to the methods of Dubowitz [6].

1

Echointensities of skeletal muscles in myotonic dystrophy (in order of their abnormality) Muscle

Median deviation of echointensities from the normal value* + 2.3 SD + 2.1 SD + 1.7 SD + 1.7 SD + 1.5 SD + 1.5 SD + 1.4 SD + 1.3 SD + 1.3 SD + 1.2 SD + 0.9 SD + 0.8 SD + 0.8 SD + 0.7 SD + 0.7 SD + 0.7 SD + 0.5 SD + 0.0 SD -0.1 SD

Statistics**

z = 4.86; z = 6.80; z = 6.39; z = 3.26; 2 = 6.06;

P