Pins & Needles sensation in Skin

Sub acute combined degeneration is progressive degeneration of the spinal cord due to vitamin B12 deficiency.
The disorder begins with a general feeling of weakness. Tingling, a pins-and-needles sensation, and numbness are felt in both hands and feet. These sensations tend to be constant and to gradually worsen. People may not be able to feel  vibrations and may lose the sense of where their limbs are (position sense). The limbs feel stiff, movements become clumsy, and walking may become difficult. Reflexes may be decreased, increased, or absent. Vision may be reduced. People who have this disorder may become irritable, apathetic, drowsy, suspicious, and confused. Their emotions may change rapidly and unpredictably.

Symptoms include muscle weakness, clumsiness, tingling, and other abnormal sensations.
It is due to a deficiency of vitamin B12, which usually also causes pernicious anemia. Usually, the deficiency is not related to diet but to the body’s inability to absorb vitamin B12.
Vitamin B12 is necessary for the formation and maintenance of a fatty sheath (myelin sheath) that surrounds some nerve cells and that speeds transmission of nerve signals. In subacute combined degeneration, the sheath is damaged, causing sensory and motor nerve fibers from the spinal cord to degenerate. The brain, nerves of the eyes,and peripheral nerves are sometimes also damaged. 

Diagnosis and Treatment

Blood tests to measure levels of vitamin B12 can confirm the deficiency. Recovery is more likely if the disorder is treated early. When treated within a few weeks after symptoms appear, most people recover completely. If treatment is delayed, the progression of symptoms may be slowed or stopped, but full  recovery of lost function is less likely. 
NOTE: The above information is only for awareness purpose,please, consult good physician before start diagnosis .