Tohoku J. Exp. Med., 2007, 211(3)

Case Report

Neonatal-Onset Brainstem Reticular Reflex Myoclonus Following a Prenatal Brain Insult: Generalized Myoclonic Jerk and a Brainstem Lesion

YOSUKE KAKISAKA,¹ KAZUHIRO HAGINOYA,¹ NORIKO TOGASHI,¹ TARO KITAMIURA,¹ MITSUGU UEMATSU,¹ NAOMI HINO-FUKUYO,¹ SHIGEO KURE,² JUNKO SAITO,³ SETSUKO KITAOKA,³ SHUEI WATANABE,⁴ HIDETO YOSHIKAWA,⁴ TAKAHIRO NARA,⁵ YOICHI SUZUKI⁶ and SHIGERU TSUCHIYA¹

¹Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai, Japan
²Department of Medical Genetics, Tohoku University Graduate School of Medicine, Sendai, Japan
³Department of Pediatrics, Tohoku Kosei Nenkin Hospital, Sendai, Japan
⁴Department of Neurology, Miyagi Children's Hospital, Sendai, Japan
⁵Department of Rehabilitation, Miyagi Children's Hospital, Sendai, Japan
⁶Department of Public Health, Chiba University Graduate School of Medicine, Chiba, Japan

Brainstem reticular reflex myoclonus (BRRM) is characterized by sudden, generalized, shock-like movements that can be elicited by sensory stimulation. We present a boy, born after 35 weeks gestation, who was diagnosed with neonatal-onset BRRM. Within 1 hr of birth, the patient showed spasticity and generalized clonic movements of all limbs elicited with tactile stimulation anywhere on the body. Surface electromyography showed co-contraction of agonistic and antagonistic muscles, revealing that his generalized clonic movements were tremulous myoclonus in nature. Brain magnetic resonance imaging (MRI) at 21 hrs after birth disclosed high-intensity lesions in the Rolandic area, thalamus, basal ganglia, and brainstem, including the dorsal pons and medulla, the center of BRRM, in T1-weighted images. Follow-up MRI at 1 month revealed dramatic improvement in the pontine lesion. The patient showed gradual remission of the characteristic movements, which disappeared at 1 year of age, but the patient died unexpectedly at 1 year and 3 months. In conclusion, neonatal BRRM arises as a result of severe brainstem injury, and the associated lesions may only be seen temporarily on MRI taken soon after birth.

keywords —— prenatal brain insult; brainstem lesion; brainstem reticular reflex myoclonus; stimulus-sensitive generalized clonic movement

© 2007 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2007, 211, 303-308

Correspondence: Yosuke Kakisaka, Department of Pediatrics, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.

e-mail: kakisuke@mui.biglobe.ne.jp