Sudden cramps in the hand into a chicken-claw shape can not be broken, may be due to abnormal contraction of skeletal muscle hand spasms, or cerebral ischemia, and so on. 1. Abnormal contraction of skeletal muscles: Abnormal contraction of skeletal muscles, resulting in hand spasms, occasionally claw-shaped hand, this situation has more reasons, such as calcium deficiency, usually after a period of calcium supplementation, the symptoms can be significantly relieved. 2. Cerebral ischemia: Cerebral ischemia may be caused by cardiovascular disease, which leads to central nervous system dysfunction, abnormal nerve excitation and muscle contraction, resulting in claw-shaped hand. The claw-shaped hand may also be caused by other reasons, such as spinal cord compression, etc. It is recommended to consult a doctor as soon as possible for a clear diagnosis and targeted treatment.