Is one sign of an anxiety attack having a seizure like experience? hands curled in and shaking of the body

No: Seizures are rarely a part of an anxiety attack. Anxiety attacks are usually characterized by feelings of dread or fear of death, palpitations, shaking, shortness of breath, chest pain, G.I. Discomfort, feeling lightheaded, fear of loss of control, and chills or hot flashes.

Not usually: Anxiety can perhaps mimic a seizure and many people shudder, shake and have motor components. Seizures can be very serious and need to be diagnosed by a physician. This can be hard to tell without further tests.