Spastic paraplegia type 2

Spastic paraplegia type 2 belongs to a group of genetic disorders known as hereditary spastic paraplegias. These disorders are characterized by muscle stiffness (spasticity) and weakness that worsens over time and paralysis of the lower limbs (paraplegia). Hereditary spastic paraplegias are divided into two types: pure and complex. The pure (also called uncomplicated) types only involve the legs. The complex (also called complicated) types involve the lower limbs and can also affect the upper limbs to a lesser degree. The complex type can also affect the structure or function of the brain. It can also affect the network of nerves (the peripheral nervous system) that connects the brain and spinal cord to muscles and sensory cells that detect sensations such as touch, pain, heat, and sound. 

Spastic paraplegia type 2 can be classified as either pure or complex, depending on the signs and symptoms. The pure type of this condition is more common. The complex type of spastic paraplegia type 2 is sometimes called hypomyelination of early myelinating structures (HEMS).

People with the pure type of spastic paraplegia type 2 experience spasticity in the leg muscles. Over time, affected individuals may lose the ability to walk. Some affected individuals may also have poor bladder control. The signs and symptoms of spastic paraplegia type 2 usually appear between the ages of 1 and 5 years, but it can develop later in life. Individuals with spastic paraplegia type 2 typically have a normal lifespan.

In addition to leg spasticity and poor bladder control, people with HEMS can also experience problems with movement and balance (ataxia); involuntary movements of the eyes (nystagmus); and involuntary, rhythmic shaking (tremor). They may also have mild intellectual disabilities and degeneration (atrophy) of the optic nerves, which carry information from the eyes to the brain. The signs and symptoms of HEMS also typically appear between the ages of 1 and 5 years. Individuals with HEMS usually survive into mid to late adulthood.