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KembaraXtra-Medicine- Anterior Cutaneous Nerve Entrapment Syndrome (ACNES)
Definition
Anterior cutaneous nerve entrapment syndrome (ACNES) is a pain disorder caused by entrapment of the cutaneous branches of the lower thoracoabdominal intercostal nerves (T8–T12) at the lateral border of the rectus abdominis muscle. As these nerves travel between the internal oblique and transversus abdominis muscles and then make a sharp turn to enter the rectus sheath, they become vulnerable to compression. Muscle contraction can further exacerbate this compression, resulting in sharp, localized abdominal wall pain that may radiate along the affected nerve on the same side of the abdomen. The pain is typically reproducible with palpation, and a positive Carnett sign supports the diagnosis. ACNES is frequently underdiagnosed or misdiagnosed.
Synonyms
ACNES.
ICD-10 Codes
G54.9 — Nerve root and plexus disorder, unspecified
G54.3 — Thoracic root disorders, not elsewhere classified
G58.0 — Intercostal neuropathy
G58.9 — Mononeuropathy, unspecified
Epidemiology and Demographics
ACNES accounts for approximately 2% of emergency department presentations with acute abdominal pain and may explain 15% to 30% of chronic abdominal pain cases, depending on diagnostic criteria. In adolescents, it has been identified in up to one in eight cases of acute abdominal pain. Females are affected more often than males, with a ratio of approximately 4:1. The median age of onset is between 40 and 50 years, with peak incidence in the third decade of life.
Risk Factors
Obesity is a recognized risk factor.
Clinical Presentation and Physical Findings
Patients typically report chronic, well-localized abdominal wall pain with a small (<2 cm²) point of maximal tenderness, often along the lateral edge rectus abdominis sheath, most commonly on right side. pain persists for at least one month and is aggravated by activities that tense abdominal muscles, such as standing, stretching, coughing, or sit-ups. carnett test positive, with remaining same worsening when muscles are tensed. additional findings may include a positive skin pinch test, altered sensation to light touch cold (hypoesthesia, hyperesthesia, hyperalgesia, allodynia), normal laboratory results, negative imaging studies, temporary relief following local anesthetic injection tender point.< />pan>
Etiology
The precise cause is often unclear. ACNES has been reported following laparoscopic abdominal surgery, trauma, pregnancy, infectious processes, or visceral events, suggesting that local nerve irritation or mechanical stress may precipitate symptoms.
Diagnosis
Diagnosis is clinical and supported by localized abdominal wall tenderness that worsens with muscle tensing, sensory changes over the painful area, exclusion of intra-abdominal pathology, and prompt pain relief after local anesthetic injection.
Differential Diagnosis
Consider other causes of localized abdominal pain, including visceral pathology, hernias, musculoskeletal disorders, and neuropathic pain syndromes.
Laboratory and Imaging Studies
Laboratory tests are typically normal and show no evidence of infection or inflammation. Imaging studies are used only to exclude other causes of abdominal pain based on clinical judgment and patient acuity.
Treatment
Initial management includes avoiding activities that excessively tense the abdominal muscles. First-line therapy is a trigger-point injection with local anesthetic, with or without a glucocorticoid. A repeat injection is commonly performed about one month later if symptoms recur. If multiple injections fail to provide sustained relief, chemical neurolysis may be considered.
Disposition and Follow-Up
Patients are typically managed on an outpatient basis and should return after one month for reassessment and possible repeat injection.
Complementary and Alternative Therapies
Nonsteroidal antiinflammatory drugs and tricyclic antidepressants may help with pain control, although they have not been specifically studied for ACNES.
Referral
If pain persists despite repeated trigger-point injections, referral for surgical management, chemical neurolysis, or reevaluation for alternative diagnoses is recommended.
Definition
Anterior cutaneous nerve entrapment syndrome (ACNES) is a pain disorder caused by entrapment of the cutaneous branches of the lower thoracoabdominal intercostal nerves (T8–T12) at the lateral border of the rectus abdominis muscle. As these nerves travel between the internal oblique and transversus abdominis muscles and then make a sharp turn to enter the rectus sheath, they become vulnerable to compression. Muscle contraction can further exacerbate this compression, resulting in sharp, localized abdominal wall pain that may radiate along the affected nerve on the same side of the abdomen. The pain is typically reproducible with palpation, and a positive Carnett sign supports the diagnosis. ACNES is frequently underdiagnosed or misdiagnosed.
Synonyms
ACNES.
ICD-10 Codes
G54.9 — Nerve root and plexus disorder, unspecified
G54.3 — Thoracic root disorders, not elsewhere classified
G58.0 — Intercostal neuropathy
G58.9 — Mononeuropathy, unspecified
Epidemiology and Demographics
ACNES accounts for approximately 2% of emergency department presentations with acute abdominal pain and may explain 15% to 30% of chronic abdominal pain cases, depending on diagnostic criteria. In adolescents, it has been identified in up to one in eight cases of acute abdominal pain. Females are affected more often than males, with a ratio of approximately 4:1. The median age of onset is between 40 and 50 years, with peak incidence in the third decade of life.
Risk Factors
Obesity is a recognized risk factor.
Clinical Presentation and Physical Findings
Patients typically report chronic, well-localized abdominal wall pain with a small (<2 cm²) point of maximal tenderness, often along the lateral edge rectus abdominis sheath, most commonly on right side. pain persists for at least one month and is aggravated by activities that tense abdominal muscles, such as standing, stretching, coughing, or sit-ups. carnett test positive, with remaining same worsening when muscles are tensed. additional findings may include a positive skin pinch test, altered sensation to light touch cold (hypoesthesia, hyperesthesia, hyperalgesia, allodynia), normal laboratory results, negative imaging studies, temporary relief following local anesthetic injection tender point.< />pan>
Etiology
The precise cause is often unclear. ACNES has been reported following laparoscopic abdominal surgery, trauma, pregnancy, infectious processes, or visceral events, suggesting that local nerve irritation or mechanical stress may precipitate symptoms.
Diagnosis
Diagnosis is clinical and supported by localized abdominal wall tenderness that worsens with muscle tensing, sensory changes over the painful area, exclusion of intra-abdominal pathology, and prompt pain relief after local anesthetic injection.
Differential Diagnosis
Consider other causes of localized abdominal pain, including visceral pathology, hernias, musculoskeletal disorders, and neuropathic pain syndromes.
Laboratory and Imaging Studies
Laboratory tests are typically normal and show no evidence of infection or inflammation. Imaging studies are used only to exclude other causes of abdominal pain based on clinical judgment and patient acuity.
Treatment
Initial management includes avoiding activities that excessively tense the abdominal muscles. First-line therapy is a trigger-point injection with local anesthetic, with or without a glucocorticoid. A repeat injection is commonly performed about one month later if symptoms recur. If multiple injections fail to provide sustained relief, chemical neurolysis may be considered.
Disposition and Follow-Up
Patients are typically managed on an outpatient basis and should return after one month for reassessment and possible repeat injection.
Complementary and Alternative Therapies
Nonsteroidal antiinflammatory drugs and tricyclic antidepressants may help with pain control, although they have not been specifically studied for ACNES.
Referral
If pain persists despite repeated trigger-point injections, referral for surgical management, chemical neurolysis, or reevaluation for alternative diagnoses is recommended.
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