Neurology is a medical specialty dealing with disorders of the nervous system. It comprises the diagnosis and treatment of all categories of diseases involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue, such as muscles.
The complex array of skin and muscle areas innervated by specific nerves, also named dermatomes, is examined to diagnose the existence of neurological deficits. Pain, numbness, and muscular atrophy/loss of strength of particular dermatomes are signs of pathology to a specific vertebral level. This can be the result of nerve impingement arising from a disc herniation, trauma or a neurodegenerative condition.
Nerves of the lumbar spine
Sensory and motor function controlled by the nerves of the lumbar and sacral spine and their corresponding dermatomes:
L4 medial leg
L5 1st / 2nd toes
S1 lateral foot
Muscle strength can be assessed using an empirical scale ranging from Grade 0 to 5:
5 Normal strength
4 Active power against both resistance and weight
3 Active power against gravity but not resistance
2 Active movement only with gravity elimination
1 Flicker or trace of contraction
0 No movement or contraction
Assessing paraplegia and tetraplegia
The level of paralysis is based on the ASIA Impairment Scale of The American Spinal Cord Injury Association. In order to help classify differing degrees of spinal cord injury, the ASIA impairment scale is used to compare and understand residual function.
A - Complete: No motor or sensory function in the lowest sacral segment (S4-S5)
B - Incomplete Sensory function below neurologic level and in S4-S5, no motor function below neurologic level
C - Incomplete Motor function is preserved below neurologic level and more than half of the key muscle groups have a muscle grade less than 3
D - Incomplete Motor function is preserved below neurologic level and at least half of the key muscle groups below neurologic level have a muscle grade 3
E - Normal Sensory and motor function.
Levels of paralysis
Methods to define the level of the paralysis:
Biceps jerk C5 /C6
Supinator jerk C6
Extensor digitorum reflex C7
Triceps jerk C7/ C8
Abdominal reflex T8-T12
Knee jerk L2 / L4
Ankle jerk L5 / S1 / S2
Bulbo-spongiosus reflex S2-S4
Anal reflex S5
Plantar reflex L5-S