Dooley Noted: 12/22/2015
I fully appreciate when people outside the health professions know anatomical or diagnostic terms.
These include anything from iliotibial band to carpal tunnel syndrome to one of my favorite diagnoses: sciatica.
The general public regards sciatica as any pain emanating from the back and traveling down the leg.
Perhaps some anatomical clarification is in order.
In sciatica, the sciatic nerve is the nerve if interest. It is the largest peripheral nerve of the human body. This nerve typically contains exons from spinal levels L4-S3.
This massive nerve emanates from the true pelvis into the gluteal region, via the greater sciatic foramen. It can often be entrapped and split in part by the piriformis muscle, which is located in the same foramen.
The nerve is threatened by more than just piriformis as an entrapment site. This nerve is wedged between the greater trochanter and the ischial tuberosity, two large bony prominences that, when approximated in sustained external rotation, can impinge the sciatic nerve.
This nerve also runs deep to the long head of biceps femoris, at the tendinous attachment it shares with another hamstring, the semitendinosus, at the ischial tuberosity.
The sciatic nerve innervates nothing for sensation in the thigh. The anterior, posterior lateral, and medial thigh receive cutaneous innervation from four separate nerves that are not branches of the sciatic nerve (femoral, posterior femoral cutaneous, lateral femoral cutaneous, and branches of femoral and obturator nerve, respectively).
So if your thigh is going numb, don’t blame the sciatic nerve.
While the sciatic nerve delivers motor innervation to the hamstrings at the thigh, it doesn’t deliver cutaneous innervation until reaching the leg.
Here, it supplies cutaneous innervation to the front and back of the anterolateral and posterior leg, as well as the top and bottom of the foot.
Thus, in true sciatic nerve entrapment, one would experience numbness and tingling at the anterolateral and posterior leg, as well as the top, bottom, and lateral aspects of the foot.
However, in many of those claiming to have sciatica, they’ll get radiating pain on the side of the thigh and into the leg and foot.
The lateral thigh radiating symptoms are more typical of something called radiculopathy, when a spinal nerve of one level gets entrapped at the low back. This can be a symptom of a disc herniation at the respective level of nerve distribution to the skin, an area called a dermatome.
If your pain is radiating on the side of the hip and thigh, spiraling to the top of the foot, make sure you are cleared for an L4-L5 radiculopathy, due to a possible disc herniation.
If the radiating pain is more towards the back of the thigh and ending on the side of the leg and/or side of the foot laterally (pinky toe side), then make sure you are cleared for an L5-S1 radiculopathy, due to a possible disc herniation.
Your chosen practitioner has special nerve tests they can do in the office, and they may choose to verify their findings with an MRI. Remember: standard radiographs cannot show extruded disc materials.
Since the treatments for radiculopathy and sciatica are quite different, make sure to get yourself properly assessed and corrected.
As always, it’s your call.
-Dr. Kathy Dooley