Referred Pain

·         Diaphragmatic pain is frequently felt at the tip of the shoulder, reflecting common nerve root origins in the neck. It usually occurs when there is inflammation of the diaphragmatic pleura, e.g. in basal pneumonia, pleural effusions or malignant disease.

·         The majority of the sensation of pain arising from the stomach, duodenum,jejunum,ileum is poorly localized. In common with other structures of foregut origin, it is referred to the central epigastrium. Pain arising from the region of the gastro-oesophageal junction may involve innervation from the oesophagus and is commonly referred to the lower retrosternal and subxiphoid areas.

·         Pain in the anus is usually felt with a high degree of acuity and is well localized to the perineum and anal canal itself.

·         Pain arising from the parenchyma of the liver is poorly localized. In common with other structures of foregut origin, pain is referred to the central epigastrium. Stretch of or involvement of the liver capsule by inflammatory or neoplastic processes rapidly produces well-localized pain of a 'somatic' nature.

·         In common with other structures of foregut origin, pain from stretch of the common bile duct or gallbladder is referred to the central epigastrium. Involvement of the overlying somatic peritoneum produces pain which is more localized to the right upper quadrant.

·         Pain arising in the pancreas is poorly localized. In common with other foregut structures, the majority of pain arising from the pancreas is referred to the epigastrium. Inflammatory or infiltrative processes arising from the gland rapidly involve the tissues of the retroperitoneum and their supply from somatic nerves, and this is referred to the posterior paravertebral region around the lower thoracic spine.

·         The majority of the sensation of pain arising from the pulp of the spleen is poorly localized. In common with other structures of foregut origin, it is referred to the central epigastrium. Distension of the splenic capsule stretches the parietal layers of the peritoneum and produces pain localized to the posterior left upper quadrant.

·         Excessive distension of the ureter or spasm of its muscle may be caused by a stone (calculus) and provokes severe pain (ureteric colic, which is commonly, but mistakenly, called renal colic). The pain, spasmodic and agonizing, particularly if the obstruction is gradually forced down the ureter by the muscle spasm, is referred to cutaneous areas innervated from spinal segments which supply the ureter, mainly T11-L2. It shoots down and forwards from the loin to the groin and scrotum or labium majus and may extend into the proximal anterior aspect of the thigh by projection to the genitofemoral nerve (L1, 2). The cremaster, which has the same innervation, may reflexly retract the testis.

·         Sensory fibres accompany the sympathetic nerves, and so ovarian pain can be periumbilical. It is often perceived in the right or left iliac fossa due to local inflammation. Ovarian pain can also be perceived on the medial side of the thigh in the cutaneous distribution of the obturator nerve, presumably because the ovary lies close to the obturator nerve in the ovarian fossa, and so any inflammation of the ovary or peritoneum in the ovarian fossa may affect the obturator nerve.

·         Pain from tubal disease is classically described as occurring in the iliac fossa as a result of local peritoneal irritation. As with pain from the ovary, this can sometimes cause discomfort in the distribution of the obturator nerve on the medial aspect of the thigh.

·         Patients with psoas abscesses may have referred pain to the hip, groin, or knee.

 ·         This referred EAR pain can be due to problems in the oral cavity, oropharynx, hypopharynx, or larynx.