- Email: [email protected]
Siblings of Schwartz-Jampel Syndrome with abnormal muscle computed tomographic findings
Brain & Development 22 (2000) 494±497
www.elsevier.com/locate/braindev
Case report
Siblings of Schwartz-Jampel Syndrome with abnormal muscle computed tomographic ®ndings Hideki Iwata a,*, Hiroshi Ozawa a, Atsushi Kamei b, Masayuki Sasaki a, Shigeru Hanaoka a, Kenji Sugai a, Toshiaki Hashimoto a, Ikuya Nonaka a a
National Center Hospital for Mental, Nervous and Muscular Disorders, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi-cho, Kodaira, Tokyo, 187-855 1, Japan b Department of Pediatrics, Iwate Medical University, Iwate, Japan Received 30 June 2000; received in revised form 16 September 2000; accepted 25 September 2000
Abstract Schwartz±Jampel syndrome (SJS) is a disorder characterized by myotonia, joint contractures, skeletal abnormalities, facial dysmorphism and growth retardation. We present two boys of ages 4 and 8 years with SJS. Their clinical, electromyographic and histopathological ®ndings were similar to those described, except for computed tomography (CT) images that revealed diffuse high attenuation in sternocleidomastoid muscles and low attenuation in the paraspinal, quadriceps, sartorius, soleus and gastrocunemius muscles. This is the ®rst report describing abnormal muscle CT ®ndings associated with SJS. Additional studies of muscle CT might help to improve understanding of the pathogenesis of SJS. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Schwartz±Jampel syndrome; Sibling cases; Abnormal muscle computed tomography ®ndings
1. Introduction Schwartz±Jampel syndrome, also known as chondrodystrophic myotonia, is a rare disorder with clinical characteristics mostly of autosomal recessive inheritance, myotonia, joint contractures, skeletal abnormalities, facial dysmorphism and growth retardation [1,2]. The condition usually appears in childhood, although patients with earlier onset at birth or during pregnancy have been described [3]. The biochemical, cytogenetic or pathological defects speci®c to SJS are unknown. Recent genetic linkage studies demonstrated that the gene was mapped to lp34±p36 [3]. We describe for the ®rst time, two SJS siblings with abnormal muscle CT ®ndings.
2. Patients 2.1. Patient 1 This 4-year-old boy was born at full term after a normal pregnancy to non-consanguineous healthy parents. The * Corresponding author. Shinshiro City Hospital, 32-1 Kitabata, Shinshiro, Aichi 441-1387, Japan. Fax: 181-5362-22850. E-mail address: [email protected] (H. Iwata).
serum creatinine kinase (CK) level of the father was elevated to 1711 U/l but no muscle symptoms were evident. At birth the boy had ¯exion contractures of ®ngers and limited hip joint mobility. Early motor and language development appeared to be normal and he began to walk at 22 months of age. At 3 years of age, scoliosis of thoracolumbar spine developed. Examination at the age of 4 years showed that he was 101.6 cm (21.0 SD) tall, weighed 16.5 kg (average) and that the circumference of his head was 52.0 cm (10.9 SD). Mental functions were all normal. His face was expressionless with a convex pro®le, small mouth, high-arched palate, narrow palpebral ®ssures, low set ears, low posterior hair line and a short neck. Corneal opacity was absent. A pectus carinatum deformity of the chest, ¯exion contractures of ®ngers, and scoliosis of thoracolumbar spine were evident. (Fig. 1) The abdomen, genitalia, respiratory and cardiovascular systems were normal. A neurological examination showed proximal muscle weakness with a positive Gowers sign and muscular hypertrophy in sternocleidomastoid muscles. Percussion myotonia was noted at the thenar and brachioradial muscles. Knee and Achilles tendon re¯exes were absent. Routine examinations of blood and urine yielded normal results except for CK that was mildly increased to 564U/l.
0387-7604/00/$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. PII: S03 87-7604(00)0018 4-4
H. Iwata et al. / Brain & Development 22 (2000) 494±497
495
Fig. 1. Patient 1 with physical features of SJS: short neck, pectus carinatum deformity of the chest, scoliosis of the thoracolumbar spine, ¯exion contractures of ®ngers and expressionless face with convex pro®le, small mouth, low set ears and hypertrophy of the sternocleidomastoid muscles.
Amino acids, organic acids and mucopolysaccharides as screening tests for metabolic defects were negative or normal. Chromosomal studies revealed a normal male constitution. Radiographic bone studies showed additional abnormalities, including ovaric lumbar vertebrae, separated costa and epiphyseal dysplasia of the humerus. Electromyographic (EMG) studies at the anterior tibial muscle showed prolonged insertional activity without waxing and waning, absent ®brillations and fasciculation, normal voluntary contraction with normal duration, amplitude and phase and a normal interference pattern. Nerve conduction velocities were also normal. A CT scan revealed diffuse high attenuation of sternocleidomastoid muscles (Fig. 2a) and low attenuation in paraspinal (not shown), quadriceps, sartorius (Fig. 2b), soleus and gastrocunemius muscles (Fig. 2c). This was more remarkable in the lateral vastus muscle and gastrocunemius muscles. The volume of quadriceps muscles was slightly decreased. 2.2. Patient 2 This 8-year-old (a brother of patient 1) was delivered without incident after a normal pregnancy. Developmental milestones were normal. Upon examination at 8 years of age, he was 133 cm (11.1 SD) tall and weighed 30.3 kg (10.9 SD). His mental function was normal. His facial features were similar to those of patient 1 and he had lumbar kyphoscoliosis. The abdomen, genitalia, respiratory and cardiovascular systems were unremarkable. Mild proximal weakness and hypertorophy of stemoclei-
domastoid muscles were apparent. Percussion myotonia of the thenar and brachioradial muscles was elicited easily. Knee and Achilles tendon re¯exes were absent. The results of routine blood and urine examinations were normal but the CK level was mildly elevated to 405U/l. Screening tests for metabolic defects and chromosome studies revealed no abnormalities. Results of EMG studies at anterior tibial muscle were similar to those of patient 1. Nerve conduction velocities were normal. A CT scan similarly showed diffuse high attenuation in the sternocleidomastoid muscles and low attenuation in the quadriceps and soleus muscles. The quadriceps muscles were mildly atrophic. A biopsy of the biceps muscle revealed moderate variation in ®ber size in both type 1 and type 2 ®bers with several ®bers having centrally placed nuclei. Type 1 ®ber was predominant (56%) and mild ®ber type grouping, increased numbers of type 2C and type 2B ®ber de®ciency in one fascicle. The endomysium, blood vessels and peripheral nerves appeared normal (Fig. 3). 3. Discussion The SJS is characterized by peculiar face, myotonia, skeletal abnormalities and short stature [4]. There is considerable variability in clinical expression of the disorder [2] even in the same family [3] and a typical form without osteoarticular involvement was reported [5]. Both patients 1 and 2 had the typical features of peculiar face, myotonia and skeletal abnormalities. Although patient 1 was a little
496
H. Iwata et al. / Brain & Development 22 (2000) 494±497
Fig. 2. Muscle CT ®ndings of patient 1 (a, b and c), patient 2 (d, e and f) and control (g, h and i). High attenuation of sternocleidomastoid muscles (a, d). Low attenuation in parasagital, quadriceps and sartorius muscles (b, e). These ®ndings were more remarkable in patient 1. Low attenuation in soleus muscle (f) and in soleus and gastrocunemius muscles(c). a, d and g: Neck muscles at the level of thyroid. b, e and h: Thigh muscles halfway between greater trochanter and center of knee joint. c, f and i: Lower leg muscles at proximal third of the distance between lateral knee joint space and lateral malleolus.
short, the height of patient 2 was normal. The pathology of short stature has been hypothetically explained on the basis of muscular stiffness inhibiting adequate bone growth [4]. As myotonia becomes more manifest around the second or third year of life, growth disturbance may progress to be more apparent [4]. Although serum CK of the patients father was elevated, he had no other speci®c features of SJS and a report on the father of a patient who had elevated CK but no clinical features has been published [6].
The prominent ®ndings of continuous spontaneous activity in electromyography agrees with those reported. The discharge did not show the classical waxing and waning pattern as seen in myotonic dystrophy. These repetitive depolarizations of muscle cells are explained as the spontaneous opening of Na 1 channels, since the spontaneous activity is suppressed both in vitro and vivo by procainamide [4]. Histological ®ndings of SJS patients have been reported to be within normal limits in most biopsies [2], whereas
H. Iwata et al. / Brain & Development 22 (2000) 494±497
Fig. 3. Histopathological ®ndings of biceps muscle from patient 2. There is mild to moderate variation in ®ber size with type 1 ®ber predominance (56%). No structural changes are evident. NADH-TR £ 100.
myopathic and/or neuropathic ®ndings are abnormal to various degrees [7]. Published reports do not describe any disease-speci®c histological abnormalities. Muscle biopsy of patient 2 exhibited both myopathic and neuropathic changes. These consisted of a variation in ®ber size in both type 1 and 2 ®bers and type 1 ®ber predominance (56%) with mild ®ber type grouping. Nerve conduction velocities were normal in the present patients and only the muscle biopsy revealed neurogenic processes. Fowler et al. postulated from such histological ®ndings that nerve as well as muscle may be involved due to a certain membrane defect [1]. Other ®ndings of patient 2 were similar to those reported. Changes of fat in®ltration, muscle ®ber necrosis and regeneration, interstitial ®brosis and fat tissue replacement [7], were absent in patient 2. We are the ®rst to identify decreased density areas in the paraspinal, quadriceps, sartorius, soleus and gastrocunemius muscles, as well diffuse high density of sternocleidomastoid muscles by CT scanning patients with SJS. The former might indicate fat tissue replacement in muscles as described [7], although patient 2 had no fat tissue replacement in the biceps muscle. Because fat tissue replacement and interstitial ®brosis are considered to become prominent as the disease progresses [7], the brachial biceps muscle might be less signi®cantly involved in patient 2. Muscle hypertrophy in the limb, trunk and abdominal muscles has been described as one of features of SJS [2]. The present patients had moderate hypertrophic sternocleidomastoid muscles with diffusely increased density on CT. The reported Hounds®eld unit (HU) density of sternocleidomastoid muscles in patients with no neuromuscular diseases is 67:70 ^ 15:8HU [8]. The HU density of the sternocleidomastoid muscles was remarkably high at 125 HU (13.9 SD) and 123 HU (13.4 SD) in patients 1 and 2, respectively.
497
Although the biochemical basis of this density is not well understood, the relative concentration of the major contractile proteins and enzymes, together with myoglobin, hemoglobin, collagen and fat may be increased [8]. Although acute hematoma and calci®cation appear as increased attenuation on muscle CT imaging [9], our muscle biopsy as well as previous histological reports demonstrated the absence of such morphologic changes. Low attenuation of the sternocleidomastoid muscles on CT has been reported in patients with myotonic dystrophy, one of the myotonic disorders. The EMG ®nding of SJS is distinguished from that of myotonic dystrophy with the classical waxing-waning pattern although both of them belong to myotonic disorders. Persistent hypercontruction is considered as one of the possible reasons for the CT changes of SJS and myotonc dystrophy. The deferences of the pathogenesis of the hypercontruction between these two myotonic disorders might appear as the opposisional attenuations. Further neuroimaging studies are necessary to con®rm whether the present abnormal CT ®ndings are speci®c and pathognomonic to SJS.
References [1] Fowler Jr W, Layzer RB, Taylor RG, Eberle ED, Sims GE, Munsat TL, et al. The Schwartz±Jampel syndrome. Its clinical, physiological and histological expressions. J Neurosci 1974;22:127±146. [2] Moodley M, Moosa A. Chondrodystrophic myotonia (Schwartz± Jampel syndrome) in South African children. Neuropediatrics 1990;21:206±210. [3] Fontaine B, Nicole S, Topaloglu H, Ben Hamida C, Beighton P, Spaans F, et al. Recessive Schwartz±Jampel syndrome (SJS): con®rmation of linkage to chromosome 1p, evidence of genetic homogeneity and reduction of the SJS locus to a 3-cM interval. Hum Genet 1996;98:380±385. [4] Topaloglu H, Serdaroglu A, Okan M, Gucuyener K, TopcËu M. Improvement of myotonia with carbamazepine in three cases with the Schwartz±Jampel syndrome. Neuropediatrics 1993;24:232±234. [5] Figuera LE, Jimenez-Gil FJ, GarcõÂa-Cruz MO, Cantu JM. Schwartz± Jampel syndrome: an atypical form? Am J Med Genet 1993;47:526± 528. [6] Cao A, Cianchetti C, Calisti L, Virgiliis SD, Ferreli A, Tangheroni W. Schwartz±Jampel syndrome Clinical, electrophysiological and histophathological study of a severe variant. J Neurol Sci 1978;35:175±187. [7] Nonaka I, Satoyoshi E. Myotonic disorders. In: Mastaglia FL, Walton L, editors. Skeletal muscle pathology. Edinburgh: Churchill-Livingstone, 1992. pp. 337±338. [8] Buicke JA, Termote JL, Palmers Y, Crolla D. Computed tomography of the human skeletal muscular system. Neuroradiology 1979;17:127± 136. [9] Visser M, Reimers CD. Muscle imaging. In: Engel AG, Franzini-Arms C, editors. Myology, 2nd edn. McGraw-Hill: New York, 1994. pp. 795±806.
www.elsevier.com/locate/braindev
Case report
Siblings of Schwartz-Jampel Syndrome with abnormal muscle computed tomographic ®ndings Hideki Iwata a,*, Hiroshi Ozawa a, Atsushi Kamei b, Masayuki Sasaki a, Shigeru Hanaoka a, Kenji Sugai a, Toshiaki Hashimoto a, Ikuya Nonaka a a
National Center Hospital for Mental, Nervous and Muscular Disorders, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi-cho, Kodaira, Tokyo, 187-855 1, Japan b Department of Pediatrics, Iwate Medical University, Iwate, Japan Received 30 June 2000; received in revised form 16 September 2000; accepted 25 September 2000
Abstract Schwartz±Jampel syndrome (SJS) is a disorder characterized by myotonia, joint contractures, skeletal abnormalities, facial dysmorphism and growth retardation. We present two boys of ages 4 and 8 years with SJS. Their clinical, electromyographic and histopathological ®ndings were similar to those described, except for computed tomography (CT) images that revealed diffuse high attenuation in sternocleidomastoid muscles and low attenuation in the paraspinal, quadriceps, sartorius, soleus and gastrocunemius muscles. This is the ®rst report describing abnormal muscle CT ®ndings associated with SJS. Additional studies of muscle CT might help to improve understanding of the pathogenesis of SJS. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Schwartz±Jampel syndrome; Sibling cases; Abnormal muscle computed tomography ®ndings
1. Introduction Schwartz±Jampel syndrome, also known as chondrodystrophic myotonia, is a rare disorder with clinical characteristics mostly of autosomal recessive inheritance, myotonia, joint contractures, skeletal abnormalities, facial dysmorphism and growth retardation [1,2]. The condition usually appears in childhood, although patients with earlier onset at birth or during pregnancy have been described [3]. The biochemical, cytogenetic or pathological defects speci®c to SJS are unknown. Recent genetic linkage studies demonstrated that the gene was mapped to lp34±p36 [3]. We describe for the ®rst time, two SJS siblings with abnormal muscle CT ®ndings.
2. Patients 2.1. Patient 1 This 4-year-old boy was born at full term after a normal pregnancy to non-consanguineous healthy parents. The * Corresponding author. Shinshiro City Hospital, 32-1 Kitabata, Shinshiro, Aichi 441-1387, Japan. Fax: 181-5362-22850. E-mail address: [email protected] (H. Iwata).
serum creatinine kinase (CK) level of the father was elevated to 1711 U/l but no muscle symptoms were evident. At birth the boy had ¯exion contractures of ®ngers and limited hip joint mobility. Early motor and language development appeared to be normal and he began to walk at 22 months of age. At 3 years of age, scoliosis of thoracolumbar spine developed. Examination at the age of 4 years showed that he was 101.6 cm (21.0 SD) tall, weighed 16.5 kg (average) and that the circumference of his head was 52.0 cm (10.9 SD). Mental functions were all normal. His face was expressionless with a convex pro®le, small mouth, high-arched palate, narrow palpebral ®ssures, low set ears, low posterior hair line and a short neck. Corneal opacity was absent. A pectus carinatum deformity of the chest, ¯exion contractures of ®ngers, and scoliosis of thoracolumbar spine were evident. (Fig. 1) The abdomen, genitalia, respiratory and cardiovascular systems were normal. A neurological examination showed proximal muscle weakness with a positive Gowers sign and muscular hypertrophy in sternocleidomastoid muscles. Percussion myotonia was noted at the thenar and brachioradial muscles. Knee and Achilles tendon re¯exes were absent. Routine examinations of blood and urine yielded normal results except for CK that was mildly increased to 564U/l.
0387-7604/00/$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. PII: S03 87-7604(00)0018 4-4
H. Iwata et al. / Brain & Development 22 (2000) 494±497
495
Fig. 1. Patient 1 with physical features of SJS: short neck, pectus carinatum deformity of the chest, scoliosis of the thoracolumbar spine, ¯exion contractures of ®ngers and expressionless face with convex pro®le, small mouth, low set ears and hypertrophy of the sternocleidomastoid muscles.
Amino acids, organic acids and mucopolysaccharides as screening tests for metabolic defects were negative or normal. Chromosomal studies revealed a normal male constitution. Radiographic bone studies showed additional abnormalities, including ovaric lumbar vertebrae, separated costa and epiphyseal dysplasia of the humerus. Electromyographic (EMG) studies at the anterior tibial muscle showed prolonged insertional activity without waxing and waning, absent ®brillations and fasciculation, normal voluntary contraction with normal duration, amplitude and phase and a normal interference pattern. Nerve conduction velocities were also normal. A CT scan revealed diffuse high attenuation of sternocleidomastoid muscles (Fig. 2a) and low attenuation in paraspinal (not shown), quadriceps, sartorius (Fig. 2b), soleus and gastrocunemius muscles (Fig. 2c). This was more remarkable in the lateral vastus muscle and gastrocunemius muscles. The volume of quadriceps muscles was slightly decreased. 2.2. Patient 2 This 8-year-old (a brother of patient 1) was delivered without incident after a normal pregnancy. Developmental milestones were normal. Upon examination at 8 years of age, he was 133 cm (11.1 SD) tall and weighed 30.3 kg (10.9 SD). His mental function was normal. His facial features were similar to those of patient 1 and he had lumbar kyphoscoliosis. The abdomen, genitalia, respiratory and cardiovascular systems were unremarkable. Mild proximal weakness and hypertorophy of stemoclei-
domastoid muscles were apparent. Percussion myotonia of the thenar and brachioradial muscles was elicited easily. Knee and Achilles tendon re¯exes were absent. The results of routine blood and urine examinations were normal but the CK level was mildly elevated to 405U/l. Screening tests for metabolic defects and chromosome studies revealed no abnormalities. Results of EMG studies at anterior tibial muscle were similar to those of patient 1. Nerve conduction velocities were normal. A CT scan similarly showed diffuse high attenuation in the sternocleidomastoid muscles and low attenuation in the quadriceps and soleus muscles. The quadriceps muscles were mildly atrophic. A biopsy of the biceps muscle revealed moderate variation in ®ber size in both type 1 and type 2 ®bers with several ®bers having centrally placed nuclei. Type 1 ®ber was predominant (56%) and mild ®ber type grouping, increased numbers of type 2C and type 2B ®ber de®ciency in one fascicle. The endomysium, blood vessels and peripheral nerves appeared normal (Fig. 3). 3. Discussion The SJS is characterized by peculiar face, myotonia, skeletal abnormalities and short stature [4]. There is considerable variability in clinical expression of the disorder [2] even in the same family [3] and a typical form without osteoarticular involvement was reported [5]. Both patients 1 and 2 had the typical features of peculiar face, myotonia and skeletal abnormalities. Although patient 1 was a little
496
H. Iwata et al. / Brain & Development 22 (2000) 494±497
Fig. 2. Muscle CT ®ndings of patient 1 (a, b and c), patient 2 (d, e and f) and control (g, h and i). High attenuation of sternocleidomastoid muscles (a, d). Low attenuation in parasagital, quadriceps and sartorius muscles (b, e). These ®ndings were more remarkable in patient 1. Low attenuation in soleus muscle (f) and in soleus and gastrocunemius muscles(c). a, d and g: Neck muscles at the level of thyroid. b, e and h: Thigh muscles halfway between greater trochanter and center of knee joint. c, f and i: Lower leg muscles at proximal third of the distance between lateral knee joint space and lateral malleolus.
short, the height of patient 2 was normal. The pathology of short stature has been hypothetically explained on the basis of muscular stiffness inhibiting adequate bone growth [4]. As myotonia becomes more manifest around the second or third year of life, growth disturbance may progress to be more apparent [4]. Although serum CK of the patients father was elevated, he had no other speci®c features of SJS and a report on the father of a patient who had elevated CK but no clinical features has been published [6].
The prominent ®ndings of continuous spontaneous activity in electromyography agrees with those reported. The discharge did not show the classical waxing and waning pattern as seen in myotonic dystrophy. These repetitive depolarizations of muscle cells are explained as the spontaneous opening of Na 1 channels, since the spontaneous activity is suppressed both in vitro and vivo by procainamide [4]. Histological ®ndings of SJS patients have been reported to be within normal limits in most biopsies [2], whereas
H. Iwata et al. / Brain & Development 22 (2000) 494±497
Fig. 3. Histopathological ®ndings of biceps muscle from patient 2. There is mild to moderate variation in ®ber size with type 1 ®ber predominance (56%). No structural changes are evident. NADH-TR £ 100.
myopathic and/or neuropathic ®ndings are abnormal to various degrees [7]. Published reports do not describe any disease-speci®c histological abnormalities. Muscle biopsy of patient 2 exhibited both myopathic and neuropathic changes. These consisted of a variation in ®ber size in both type 1 and 2 ®bers and type 1 ®ber predominance (56%) with mild ®ber type grouping. Nerve conduction velocities were normal in the present patients and only the muscle biopsy revealed neurogenic processes. Fowler et al. postulated from such histological ®ndings that nerve as well as muscle may be involved due to a certain membrane defect [1]. Other ®ndings of patient 2 were similar to those reported. Changes of fat in®ltration, muscle ®ber necrosis and regeneration, interstitial ®brosis and fat tissue replacement [7], were absent in patient 2. We are the ®rst to identify decreased density areas in the paraspinal, quadriceps, sartorius, soleus and gastrocunemius muscles, as well diffuse high density of sternocleidomastoid muscles by CT scanning patients with SJS. The former might indicate fat tissue replacement in muscles as described [7], although patient 2 had no fat tissue replacement in the biceps muscle. Because fat tissue replacement and interstitial ®brosis are considered to become prominent as the disease progresses [7], the brachial biceps muscle might be less signi®cantly involved in patient 2. Muscle hypertrophy in the limb, trunk and abdominal muscles has been described as one of features of SJS [2]. The present patients had moderate hypertrophic sternocleidomastoid muscles with diffusely increased density on CT. The reported Hounds®eld unit (HU) density of sternocleidomastoid muscles in patients with no neuromuscular diseases is 67:70 ^ 15:8HU [8]. The HU density of the sternocleidomastoid muscles was remarkably high at 125 HU (13.9 SD) and 123 HU (13.4 SD) in patients 1 and 2, respectively.
497
Although the biochemical basis of this density is not well understood, the relative concentration of the major contractile proteins and enzymes, together with myoglobin, hemoglobin, collagen and fat may be increased [8]. Although acute hematoma and calci®cation appear as increased attenuation on muscle CT imaging [9], our muscle biopsy as well as previous histological reports demonstrated the absence of such morphologic changes. Low attenuation of the sternocleidomastoid muscles on CT has been reported in patients with myotonic dystrophy, one of the myotonic disorders. The EMG ®nding of SJS is distinguished from that of myotonic dystrophy with the classical waxing-waning pattern although both of them belong to myotonic disorders. Persistent hypercontruction is considered as one of the possible reasons for the CT changes of SJS and myotonc dystrophy. The deferences of the pathogenesis of the hypercontruction between these two myotonic disorders might appear as the opposisional attenuations. Further neuroimaging studies are necessary to con®rm whether the present abnormal CT ®ndings are speci®c and pathognomonic to SJS.
References [1] Fowler Jr W, Layzer RB, Taylor RG, Eberle ED, Sims GE, Munsat TL, et al. The Schwartz±Jampel syndrome. Its clinical, physiological and histological expressions. J Neurosci 1974;22:127±146. [2] Moodley M, Moosa A. Chondrodystrophic myotonia (Schwartz± Jampel syndrome) in South African children. Neuropediatrics 1990;21:206±210. [3] Fontaine B, Nicole S, Topaloglu H, Ben Hamida C, Beighton P, Spaans F, et al. Recessive Schwartz±Jampel syndrome (SJS): con®rmation of linkage to chromosome 1p, evidence of genetic homogeneity and reduction of the SJS locus to a 3-cM interval. Hum Genet 1996;98:380±385. [4] Topaloglu H, Serdaroglu A, Okan M, Gucuyener K, TopcËu M. Improvement of myotonia with carbamazepine in three cases with the Schwartz±Jampel syndrome. Neuropediatrics 1993;24:232±234. [5] Figuera LE, Jimenez-Gil FJ, GarcõÂa-Cruz MO, Cantu JM. Schwartz± Jampel syndrome: an atypical form? Am J Med Genet 1993;47:526± 528. [6] Cao A, Cianchetti C, Calisti L, Virgiliis SD, Ferreli A, Tangheroni W. Schwartz±Jampel syndrome Clinical, electrophysiological and histophathological study of a severe variant. J Neurol Sci 1978;35:175±187. [7] Nonaka I, Satoyoshi E. Myotonic disorders. In: Mastaglia FL, Walton L, editors. Skeletal muscle pathology. Edinburgh: Churchill-Livingstone, 1992. pp. 337±338. [8] Buicke JA, Termote JL, Palmers Y, Crolla D. Computed tomography of the human skeletal muscular system. Neuroradiology 1979;17:127± 136. [9] Visser M, Reimers CD. Muscle imaging. In: Engel AG, Franzini-Arms C, editors. Myology, 2nd edn. McGraw-Hill: New York, 1994. pp. 795±806.