Nonhernia Causes of Inguinal Pain in the Elderly

Case Vignette

A 68-year-old male had a laparoscopic right inguinal hernia repair using mesh, and postoperatively developed severe pain in the right inguinal area radiating to the right testis. Abdominal and scrotal ultrasounds were negative. An ilioinguinal nerve block was performed with 0.25% bupivacaine and methylprednisolone with immediate relief. He was pain-free for 36 hours, but then the pain recurred. Another injection of the same medication was given several weeks later with a similar response. A course of a nonsteroidal anti-inflammatory drug (NSAID) was prescribed for 2 weeks with no improvement. A right inguinal exploration was performed, and the right ilioinguinal nerve was identified as entrapped in the marlex mesh. The nerve was divided at the internal inguinal ring, and the patient had relief of pain but was hypesthetic in the dermatome of L1 and the right hemiscrotum. The patient was satisfied with the result and was able to return to all activities without restrictions.

Introduction

Inguinal hernias are certainly one of the most common causes of inguinal pain in elderly patients. However, nonhernia causes also occur and are often a diagnostic and therapeutic dilemma. This article will review the nonhernia causes of inguinal pain and the approach to managing these conditions.

Differential Diagnosis

There are several different disorders in addition to inguinal hernias that can cause pain in the inguinal area in elderly patients. In order to correctly diagnose the cause of inguinal pain in the elderly patient, a thorough history must be taken, and the onset, character, and severity of the pain must be accurately determined.

Multiple urologic disorders can cause inguinal pain, often occurring with associated genital pain.¹ Localization and characterization of the associated pain in combination with an analysis of the patient’s urologic history will determine if the inguinal pain is the result of a urologic disorder. Many urologic disorders have similar presentations, and it is important to review all symptoms. For example, the symptoms of chronic prostatitis and interstitial cystitis (IC) often mimic the symptoms of a urinary tract infection (UTI), including dysuria, frequency, urgency, and nocturia.² Chronic prostatitis is characterized by genital or pelvic pain lasting more than 3 months and is often associated with urinary and sexual disturbances.³ Prostatitis may have a bacterial or nonbacterial etiology. Chronic bacterial prostatitis (CBP) typically presents as recurrent UTIs. Nonbacterial prostatitis is referred to as chronic pelvic pain syndrome (CPPS).³ Prostatitis may be the cause of inguinal pain in an elderly patient but is more common in young to middle-aged men. Interstitial cystitis/painful bladder syndrome (IC/PBS) is another possible urologic cause of inguinal pain in the elderly population. While it is seen more often in women, men are sometimes affected. There are no physical diagnostic signs, and because the symptoms of IC/PBS, such as dysuria, frequency, urgency, and/or nocturia, are seen in several different urologic conditions, its diagnosis has conventionally been based on the exclusion of other disorders with similar symptoms.² Some researchers have identified a set of criteria among women with recent onset of IC/PBS.⁴ They found that 97% of women included in two different studies of IC/PBS reported pain that worsened with certain foods or liquids and/or worsened with bladder filling and/or improved with urination. These criteria may be useful in determining a diagnosis of IC.

Epididymitis is usually secondary to a bacterial infection of the epididymis and could create referred pain to the inguinal area in an elderly patient. However, epididymitis is mostly seen in young, sexually active men,⁵ and the pain associated with this condition is typically localized to the epididymis and scrotum without referral to the inguinal area.⁶ A varicocele may cause groin pain in an elderly patient; however, it is typically seen in young men. Right-sided inguinal pain accompanied by a right-sided varicocele, especially those that do not collapse when the man is placed in the supine position, can be a sign of a tumor thrombus in the inferior vena cava from a hypernephroma. Solitary right-sided varicoceles may be associated with renal and retroperitoneal masses, including renal cell carcinomas.⁷ A hydrocele may cause inguinal pain accompanied by a painless swelling in the scrotal area. Hydroceles can usually be diagnosed by transillumination in the office with a pen light.

If an elderly patient complains of inguinal pain following a recent inguinal surgery, nerve entrapment syndrome is a possible cause. Nerve entrapment is also common after lower abdominal and orthopedic surgery, and idiopathic cases are rare ^8,9 The high incidence of nerve entrapment following orthopedic surgery makes it an important consideration in the elderly patient. Nerve entrapment can also occur in women after childbirth, but this etiology is unlikely in elderly patients, as they have passed childbearing age.⁹ There are several different nerves that may become entrapped, causing inguinal pain. The most common nerves affected are the ilioinguinal nerve, the genitofemoral nerve, and the lateral femoral cutaneous nerve (LFCN).^8,9 Nerve entrapment syndromes usually present without other symptoms,⁸ and the patient’s genital examination will appear normal. The symptomology of the entrapment of the different nerves may be similar, making a bedside differential diagnosis difficult.⁹ In both ilioinguinal nerve entrapment and genitofemoral nerve entrapment, the patient may present with pain in the inguinal region. Pain can radiate to the scrotum or labia, mimicking a urologic problem.⁹ LFCN entrapment or meralgia paresthetica (pain, tingling, or sensory loss associated with compression of the LFCN below the inguinal nerve) can also be difficult to differentiate from genitofemoral nerve entrapment, as both conditions occur with pain and/or numbness in the upper thigh as well as in the inguinal areas.^8,9 However, genitofemoral nerve entrapment usually affects the L1 and L2 dermatomes, including the medial thigh region.¹⁰ Meralgia paresthetica will typically cause a patient to experience unilateral symptoms in the region of the LFCN, including the L2 and L3 dermatomes, instead of the medial thigh area.⁸ Because these entrapment syndromes are very difficult to differentiate with only a history and physical exam, a nerve block in the region of the nerve that is believed to be entrapped is the diagnostic method of choice for many physicians. If immediate relief is achieved by a nerve block in a certain area, the specific nerve affected can be determined.^8,9 If there is any question regarding the diagnosis or treatment, consider referral to a neurologist for further diagnosis and treatment.

Urolithiasis is a problem that affects approximately 2-3% of the general population.¹¹ Urolithiasis typically presents with a sudden onset of excruciating unilateral flank or lower abdominal pain. This pain is often referred to the lower abdomen or ipsilateral inguinal area. It is thought that the stone must at least partially obstruct the ureter to generate the incapacitating, colicky pain that is characteristic of urolithiasis. Stones that are more distal can produce symptoms such as bladder instability, urinary frequency, dysuria, and/or pain radiating to the genitals. Urolithiasis is very likely to recur in a patient who has previously been diagnosed with kidney stones; it also is more common in patients with a family history of kidney stones.¹¹

Muscle, ligament, or joint problems are other possible causes of referred inguinal pain. Problems of this nature should be given consideration, as they occur frequently in the elderly population. If inguinal pain occurs at the onset of walking or other physical activity, then muscle, ligament, or joint problems, particularly hip pathology, are more likely explanations of the inguinal pain.¹ As mentioned, when the patient has a pain radiating from the back to the inguinal area, lumbar disk disease or other back pathology is likely.¹ Patients with degenerative disk disease occasionally complain of associated inguinal pain. It is sometimes possible to locate the affected disk according to the characteristics and location of the referred groin pain (ie, in which dermatome it is located).¹² In the case of suspected lumbar disk disease or other musculoskeletal problems, referral to an orthopedic surgeon or neurosurgeon is recommended.

Herpes zoster, or shingles, is another condition that may cause dermatomal pain in the inguinal area. Herpes zoster is an important diagnosis to consider when dealing with an elderly patient, as the incidence of this condition increases drastically among patients over age 50 years. A patient with herpes zoster will experience pain in a specific dermatome that may last for days, weeks, or months. This presentation often can confuse caregivers and physicians; however, the development of the characteristic vesicular rash along the route of the affected dermatome will confirm the presence of herpes zoster. Some patients may also exhibit very sensitive skin in the area of the affected dermatome prior to the onset of the rash. This can be a clue that the patient is affected by herpes zoster before the rash develops.¹³

Other less common causes of inguinal pain include appendicitis, cholecystitis, diverticulitis, colitis, constipation, hernias, arterial aneurysms, renal tumors, ureteral tumors, and other causes of ureteral obstruction.

Work-Up of a Patient with Inguinal Pain

A urologic condition is a likely diagnosis if a patient is experiencing genital pain or urologic symptoms (ie, burning with urination, dysuria, hematuria, frequency, urgency) in addition to the inguinal pain. If a urologic condition is the suspected cause of inguinal pain, a physical exam can be helpful in determining a diagnosis. A physical exam can help differentiate diagnosis of epididymitis and varicocele. A patient with epididymitis will be tender over the epididymis6 and may have a fever.⁵ If a varicocele is suspected, the patient should be examined in both standing and supine positions. If the varicocele is large, it will be palpable when the patient is in the upright position and could be visible through the scrotal skin when the patient is standing.¹⁴ A very small varicocele becomes palpable when the patient performs the Valsalva maneuver. An ultrasound can be a helpful diagnostic tool when differentiating between a varicocele, epididymitis, and a more serious condition, such as a testicular tumor.¹⁴ An ultrasound can detect varicoceles that are not palpable on physical exam, though most clinicians consider the varicocele to be subclinical if it is not palpable with the Valsalva maneuver.¹⁴ Typically, the varicocele collapses when the man is supine. However, if it does not, it can be a sign of a tumor thrombus in the inferior vena cava from a hypernephroma. Solitary right varicoceles may be associated with renal and retroperitoneal masses, including renal cell carcinomas.⁷

A urinalysis should always be preformed when a urological condition is suspected. A negative urinalysis can rule out several urologic conditions, such as UTI, urinary tract obstruction, urolithiasis, and bacterial epididymitis. If the urinalysis is positive, the physician should order further urine tests to illuminate the cause of the irregularities in the urine. A urine culture is useful for positively determining infections related to UTI, prostatitis, and bacterial epididymitis. A 4-glass or a 2-glass test can also confirm the diagnosis of prostatitis. A study by Luzzi³ indicated that a 2-glass test might be equally as effective as a 4-glass test. This 2-glass test consists of examination of the urine before and after prostatic massage.³ The findings of more than 10 WBC/hpf in the postprostatic massage urine specimen is highly indicative of prostatitis. Patients with prostatitis may also show an elevated level of prostate-specific antigen (PSA). If the treatment course of antibiotics lowers their PSA level, prostatitis is assumed to be the cause of the elevated level.⁵ However, it is prudent to continue to watch it, as a high PSA level in an elderly man is considered to be a marker for prostate cancer.¹⁵

If a patient is experiencing urologic conditions in conjunction with inguinal pain and bladder or abdominal pain, it is possible that the patient has IC. This condition is more common in women but can occur in men. There is no diagnostic test for IC. As mentioned above, many patients do experience symptoms similar to those associated with UTIs, such as dysuria, urgency, and frequency.² A patient with IC may exhibit one, all, or none of these symptoms, making it difficult to diagnose the condition. However, others suggest that there are symptoms that are common to all patients with this condition.⁴ They hypothesize that pain that worsens with certain food or drink, worsens with bladder filling, and/or improves with urination is indicative of this condition. If a patient exhibits these symptoms, IC is likely.

Pain in the inguinal region radiating to either the thigh or genitalia without other associated symptoms may suggest nerve entrapment of the ilioinguinal nerve, the LFCN, or the genitofemoral nerve. Pain in the iliac fossa and inguinal region following abdominal surgery suggests ilioinguinal neuropathy. In some cases the pain will radiate to the genital area and medial thigh. The pain is usually worsened by walking or hip extension and is relieved by hip flexion. The area may also exhibit sensory abnormalities such as hyperesthesia. If a patient has ilioinguinal nerve entrapment, the physical exam may show that the patient is tender upon palpation approximately 2-3 cm medial and below the anterior superior iliac spine. The needle electromyography when used as a deep stimulating electrode may assist in the diagnosis of ilioinguinal nerve entrapment. When it stimulates the ilioinguinal nerve, it will elicit neuropathic pain, radiating toward the scrotum.⁹ Injection with local anesthetic can also be used to simultaneously diagnose and treat the nerve entrapment. Diagnosis and relief of ilioinguinal nerve entrapment can be achieved by an ilioinguinal nerve block using 1% lidocaine injected at the level of the pubic tubercle. Most patients will receive immediate relief after the injection.¹⁶ If the injection does not offer immediate relief, the pain may instead be caused by genitofemoral nerve entrapment requiring further treatment.⁹ Symptoms of meralgia paresthetica involve the anterolateral thigh and are worsened with standing, walking, or adduction of the thigh. Though common, meralgia paresthetica is often misdiagnosed as lumbar radiculopathy.^8,9 However, unlike lumbar radiculopathy, there is never muscle weakness or loss of deep-tendon reflexes. Diagnosis is made by history and physical examination, while magnetic resonance imaging (MRI) and an electromyogram and nerve conduction studies may be performed to rule out other causes.⁸

If a patient complains of a sudden onset of abdominal or flank pain with pain radiating to the inguinal area, urolithiasis is a probable diagnosis.¹¹ Urinalysis should be performed to test the urine and rule out infection and microscopic hematuria. Plain film radiography of the kidneys, ureters, and bladder (KUB) is used to determine if kidney stones are present. This diagnosis can be confirmed with a spiral computed tomography (CT) scan, which can confirm the presence of kidney stone, as it can identify all types of stones in all locations. If the KUB is negative, but kidney stones are still suspected, it is possible that the stones are radiolucent (ie, stones of a uric acid or cysteine composition). A KUB can detect the presence of radiopaque kidney stones, but an abdominal ultrasound is needed to detect the presence of radiolucent stones (ie, citric acid).¹¹ These diagnostic imaging tests are also used to eliminate other common causes of abdominal and inguinal pain, such as appendicitis, cholecystitis, diverticulitis, colitis, constipation, hernias, arterial aneurysms, renal tumors, ureteral tumors, and other causes of ureteral obstruction.¹¹

Inguinal pain occurring with back pain is indicative of a number of musculosketetal problems. Patients with back pain radiating into the groin that worsens when standing or sitting without back support may be suffering from lumbar disk disease. In this condition, pain can radiate to the buttocks, legs, and inguinal area as well. A spinal CT or MRI can confirm a diagnosis of lumbar disk disease.¹⁷ There are several different musculoskeletal disorders that can affect the muscles, joints, and ligaments. If the pain worsens with walking or other activity, a disorder of this type is likely. A physical exam is helpful in diagnosing a musculoskeletal disorder. Any site of swelling and/or tenderness should be noted, and range-of-motion tests should be administered. Diagnostic imagining can be helpful in supporting the diagnosis. X-ray tests do not show muscles, ligaments, or tendons, but are useful when a fracture, bone tumor, or bone infection is suspected. A CT scan will give a more precise exam of the bone when a problem is found on the x-ray. A bone scan is used when infection or metastatic cancer is suspected. A MRI will show abnormalities in the soft tissue, supplementing the diagnosis of a muscle, ligament, or joint problem. Joint problems specifically can be investigated using joint aspiration and/or arthroscopy. Joint aspiration involves aspirating and analyzing a small amount of synovial fluid from the affected joint and is typically performed if infection, gout, or pseudogout is suspected. Arthroscopy of the joint space enables the surgeon to see the problem and biopsy or repair any defect, if necessary. This technique is usually employed if synovitis; tears in the ligament, tendon, or cartilage; or loose pieces of bone are suspected to be causing the pain. These techniques are more invasive than the imaging techniques but do provide accurate diagnosis.¹⁸

When a patient experiences pain in a specific dermatome for several weeks or months, it can often be mistaken for a musculoskeletal problem. However, a thorough history and physical exam could help the physician determine if herpes zoster is present. The skin in the area of the affected dermatome will often be very sensitive, providing a clue to the diagnosis of herpes zoster before the characteristic vesicular rash develops. Eventually, the virus will infect the dermis and epidermis to produce the rash along the affected dermatome and confirm the diagnosis. Herpes zoster is typically a clinical diagnosis, but some laboratory tests can be helpful in confirming the diagnosis and determining if there is organ involvement. Immunofluorescence antigen detection is the most rapid and effective way of determining the presence of herpes zoster. A herpes zoster culture is slower and less sensitive, but it remains the standard way of diagnosing the infection.¹³

Treatment

Once a diagnosis has been made, the physician may then proceed with treatment or, depending on the severity of the condition, refer the patient to the appropriate specialist. Antibiotics are the typical choice for treatment of prostatitis⁵ and epididymitis.⁶ In mild cases of prostatitis, an oral fluoroquinolone can be administered for 7-10 days. In more severe cases, high doses of broad-spectrum antibiotics should be used until the infection is brought under control. Oral antibiotic therapy can then be used for an additional 2-4 weeks.⁵ When treating epididymitis and UTI, it is important to determine which microbial agent is present; a specific antimicrobial therapy can then be administered.⁵ A clinically significant varicocele will require referral to a urologist. Depending on the severity of the varicocele, it may require ligation of the internal spermatic vein, or the internal spermatic vein can be embolized by a radiologist.¹⁴

IC can be a difficult disorder to manage, as no standard method of treatment has been determined. A diet change with less-irritating food and drink is recommended if patients can tell that their condition is affected by certain substances. Antihistamines or pentosan polysulfate sodium can be given orally and provide some relief for some, but not all, patients. Immunosuppressive drugs such as prednisone and cyclosporin and tricyclic antidepressants such as amitriptyline have been shown to provide relief for some patients as well.¹⁰ Hydrodistension, urethral dilation, and intravesical treatments such as dimethyl sulfoxide (DMSO) and a combination of heparin, lidocaine, and sodium bicarbonate also provide variable relief to a subset of patients.¹⁹

The management of urolithiasis depends on the size and location of the stones.²⁰ If the stone is less than 5 mm, it is likely to pass within 2-4 weeks.¹¹ The rate of spontaneous passage is 29-98% for a stone less than 5 mm located in the proximal ureter and 71-98% for a stone less than 5 mm located in the distal ureter.²⁰ Analgesic medication and alpha blockers can be prescribed to relieve pain and speed the passage of the stone.¹¹ A review of several studies demonstrated that administration of alpha blockers increased the rate of stone passage.²⁰ These studies also found that alpha blockers both decreased the time to stone expulsion and decreased the pain associated with the passage of the stone. Patients should be advised to strain the urine to capture the stone for chemical analysis. Knowledge of the composition of the stone is important for prevention of future stones. If a stone is greater than 5 mm or it does not pass within 4 weeks, surgical intervention may be needed and referral to a urologist is recommended.¹¹

As mentioned, when a patient is suffering from nerve entrapment, an injection of a local anesthetic, 1% lidocaine, offers relief within minutes.^8,9 If it does not alleviate the pain, the patient may have a genitofemoral nerve entrapment, meralgia paresthetica, lumbar disk disease, or another back or hip pathology.^8,9 In genitofemoral nerve entrapment, treatment with a paravertebral block of the L1 and L2 spinal nerves should be considered.⁹ Conservative treatment for meralgia paresthetica includes weight loss, avoiding thick, heavy belts (which can compress the inguinal ligament), and use of NSAIDs and neuropathic agents.⁸ If conservative management fails, a diagnostic and potentially therapeutic local anesthetic injection, targeting the LFCN 1 inch medial to the anterior superior iliac spine and inferior to the inguinal ligament, is indicated. Surgery is an alternative should these treatments fail. If there is any question about the diagnosis or administration of treatment of nerve entrapment, referral to a neurosurgeon should be considered. In the case of suspected back or hip pathology, referral to an orthopedic or neurosurgeon is suggested.

Musculoskeletal disorders such as lumbar disk disease, osteoarthritis, and other back and hip pathologies can be treated with physical therapy, steroid injections, narcotic pain medication, or muscle relaxants.^17,21 However, these are not long-term treatments. If the patient’s pain becomes severe, surgical treatment is an option. In this case, the patient should be referred to an orthopedic or neurosurgeon for further evaluation and treatment.¹⁷

The main treatment goal for a patient affected by herpes zoster is reduction or elimination of pain.13 Antiviral therapy, NSAIDs, and analgesics are the medications typically used to treat herpes zoster. Antiviral drugs are effective in some cases when administered within 72 hours from the onset of the rash. Anti-inflammatory corticosteroids do cause some adverse side effects such as gastrointestinal symptoms, edema, and granulocytosis. They do provide some relief, but are only recommended for patients who are otherwise healthy. In some cases, antiviral medications and NSAIDs are effective at dealing with the pain of herpes zoster. However, both opiates and nonopiate analgesic medication can be used to control the pain, if necessary.¹³

Summary

Nonhernia causes of inguinal pain in the elderly can be diagnosed with a thorough history and physical exam, and some diagnostic tests that are available to nearly every clinician who cares for geriatric patients. Relief is available for most of these conditions, and referral is required in special circumstances.

The authors report no relevant financial relationships.

Ms. Ulrich is a pre-med student, and Dr. Baum is Associate Clinical Professor of Urology, Tulane Medical School, New Orleans, LA.

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