Deep Gluteal Syndrome
Frequencies of clinical features
Calculating the frequencies for symptoms and signs is difficult because most reports are in the form for case reports which are often incomplete, they do not report negatives or do not report in a uniform manner. For example, low back pain covers any back pain from below the rib cage to the lower edge of the buttock. Some case reports refer to buttock pain, others to low back pain. Do the latter mean the buttock? Some reports include negatives, such as a negative straight leg raising test, while others do not. Does this mean that the latter did not test for SLR or that they did not bother to report negatives? Case series suffer from a different problem. How they define cases can over or underestimate frequencies.
The pain is felt in the buttock, down the leg or both. An estimate of frequency of buttock pain is 49% and for both buttock and low back pain 71%. Pain may be aggravated by prolonged sitting, which puts external pressure on the muscles and sciatic nerve. Estimated frequency is 40%. It could be said that the symptoms that should alert clinicians to the syndrome are buttock pain and aggravation by sitting.
On examination, pressing over the greater sciatic notch, where the sciatic nerve leaves the pelvis, may reproduce the pain. This point can be found third along an imaginary line from the greater trochanter towards the sacral hiatus.
Several tests have been suggested that, when present, are said to distinguish DGS from sciatica caused by radiculopathy or spinal sciatica. These tests, apart from tonic external rotation of the hip and digital pressure, all reproduce the patient’s pain by increasing pressure on the sciatic nerve. They do this through tensing the piriformis and related muscles either passively (forced by the examiner) or actively (performed by the patient). The diagnostic accuracy of symptoms and signs have not been established and properly designed cross-sectional studies are needed. The tests are described here.