It appears as if you are describing the symptom of hyperreflexia where patients twitch or have spastic tendencies especially when you are excited.
The numbness/tingling in your fingers is a normal physiologic reaction to excitement – some people are just more sensitive to it. The explanation relates to the calcium balance. When most people get excited, they tend to breathe faster causing them to excrete more CO2 from the blood. This increases the pH of the blood making it more basic. As your blood becomes more basic, the proteins in your blood develop a higher affinity to blood calcium and therefore decreases the amount of free calcium in the bood. This in turn results in a pseudo-hypocalcium which most people experience as a tingling/twitching/numbness in the fingers, toes, or lips.
Causes for hyperreflexia can also be due to drug side effects, electrolyte abnormalities or upper motor neuron (brain/spinal cord) disease.
Drugs such as stimulants (some of the most common include those used to treat attention deficit disorder such as Ritalin) can cause hyperreflexia. In addition, the side effects of certain classes of antipsychotic drugs can cause tremors.
Electrolyte abnormalities such as true hypocalcemia or hypomagnesemia (low calcium or low magnesium) can cause your muscles to twitch. Conversely, extremely high levels of calcium may also cause your muscles to twitch.
Neurologic diseases such as those that cause upper motor neuron diseases: amyotrophic lateral sclerosis (abbreviated ALS, Lou Gehrig’s disease), primary lateral sclerosis (abbreviated PLS), or pseudobulbar palsy. Most of these diseases are progressive and the symptoms quite severe. Therefore, with isolated finger numbness, it is unlikely you have these conditions.
Although it is completely normal for you to feel numbness in your fingers when you are excited, it is more concerning if you have the numbness when not excited. If the numbness persists or worsens, your primary doctor should perform a detailed physical exam as well as draw labs such as calcium, magnesium, and parathyroid hormone levels. If warranted a electromyogram may be performed to check the neuromuscular connections.
