Understanding Patient History
Pelvic pain comes in many forms and there are multiple etiologies. Recent history put significant psychological trauma related explanations in terms of causation. There are a significant number of pelvic pain patients where the explanation is directly related to post-operative bleeding or the delayed but directly related scar formation. The scar formation may be several years after the post-surgical intervention.
Taking a detailed history and a complete physical exam is imperative. The involved nervous system includes the various spinal nerve roots, but remembering that the innervation may in fact be coming from higher levels than one customarily thinks about such with the embryologic descent of the testicles taking the innervation from higher levels as well as the autonomic nervous system through the inferior hypogastric plexus or the sacral sympathetic nerve such as the ganglion impar.
When a patient presents with knee pain, it may be the consequence of the medial knee pain from saphenous nerve involvement that purely comes from the femoral nerve. The saphenous nerve also has the infrapatellar branch that can respond to therapeutic interventions.
Scar formation in the pelvis may lead to pain, atrophy, and denervation of the various aspects of the quadriceps femoris muscle. The genius of Dr. Alon Winnie(1) in describing the three-in-one block becomes useful in evaluating impairment around that space. The contents of the femoral sheath spread to the lateral femoral cutaneous nerves as well as to the obturator and femoral nerves.
Considering Genitofemoral Nerve Pain
Additionally, the fourth nerve is the genitofemoral nerve immediately behind the ilioinguinal ligament. Genitofemoral nerve related pain may be missed for ilioinguinal nerve related pain that can become a surgical target resulting in worse pain than previously encountered. Sitting pain can be caused by a number of conditions, but the pudendal nerve and the inferior hypogastric plexus are the two main causes. Specifically, pressure on the ischial tuberosity reproduces the sitting pain that responds to blocking the ipsilateral inferior hypogastric plexus. The technique was introduced by Dr. Plancarte for pelvic pain originating from spreading carcinoma in the cervix. The lower abdominal pain, secondary to iliohypogastric nerve, is easy to diagnose if one examines the abdominal wall by light stroking and comparing one side to the other. It is usually an entrapment neuropathy as the nerve perforates the internal oblique transversus abdominis and near the rectus sheath, becomes cutaneous nerve. Commonly seen following lower abdominal hysterectomies, pregnancy at 22-25 weeks gestation in small stature, athletic females and obese males with ventral hernia repairs using Marlex mesh, entrapment of the nerves is significantly increased, leading to severe lower abdominal allodynia. Base of the penis and vulva pain can originate from scar formation involving the pudendal and genitofemoral nerves. One must remember that the genitofemoral nerve travels within the psoas muscle and breaks to the surface at the lower end of the L3 vertebral body. One often sees groin pain after compression fractures and vertebroplasty, secondary to psoas muscle spasm and the squeezing and irritation of the genitofemoral nerve. Psoas muscle injections rapidly resolves the pain.
Gold Standard for Diagnosing Pain
The gold standard for diagnosing the pain is doing a psoas stretch by pulling the lower extremity, specifically the thigh, posteriorly, thus stretching the psoas muscle. Part of the examination must be evaluating for quadriceps muscle weakness. The patient is asked while in a sitting position to elevate the upper leg against resistance and comparing against the other side. In the presence of surgical procedures going back multiple years, determine if there was any intra-abdominal bleeding, abdominal wall hematomas or bleeding into the illiacus muscle down to the pelvic floor area where the pudendal genitofemoral and obturator nerves reside. These nerves can be evaluated by provocative testing. The obturator nerve scarring and entrapment is relatively rare but can be diagnosed by abduction laterally of the lower extremity.
The pudendal nerve can be identified as the cause of pain by pelvic examination and it needs to be felt laterally, palpating for the iliosacral ligament and close to the lateral insertion of the ligament to the ischial spine. Tenderness can be elicited by even general palpation. The inferior pudendal and genitofemoral nerves can be identified anteriorly by feeling the posterior aspect of the symphysis area towards both sides. In cases of pelvic fractures or dislocation of the coccyx, palpating the sacral coccygeal ligament can be helpful in the diagnosis. The same procedures in males can be done rectally.
