Tonic convulsions - Tonic convulsions

Japanese: 強直性痙攣 - きょうちょくせいけいれん

…It refers to an involuntary and sudden muscle contraction. When abnormal muscle contraction continues for a long time and the muscle becomes stiff, it is called a tonic convulsion, and when muscle contraction and relaxation are repeated alternately, it is called a clonic convulsion. The term convulsion has a very wide range of meanings and can be divided into several categories. (1) Convulsion: Refers to a violent generalized convulsion, such as a grand mal seizure in epilepsy. (2) Clamp: A painful convulsion, which is normally experienced as a cramp. …

From [convulsions]

…The term is used differently by different people, but it is generally used almost synonymously with convulsive seizures. It has a strong connotation of generalized tonic convulsions, and is often used for children.
[Convulsive Seizures]
Seizures are sudden, involuntary muscle contractions, and include clonic convulsions, which are repeated brief contractions (spasms), and tonic convulsions, which last from a few seconds to a few minutes.

*Some of the terminology explanations that mention "tonic convulsions" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…不随意かつ急激な筋肉の収縮をいう。筋肉の異常な収縮が長く続き筋肉がこわばった状態になるものを強直性tonic痙攣，筋肉の収縮と弛緩が交互に反復する状態を間代性clonic痙攣とよぶ。痙攣という名称は，非常に広い範囲の内容を意味しており，いくつかに分けられる。　(1)コンバルジョンconvulsion　癲癇（てんかん）の大発作に代表される全身性の激しい痙攣をさす。(2)クランプcramp　有痛性の痙攣で，正常でも〈こむらがえり〉として経験される。…