The axonal carpal tunnel syndrome

Area of Science:

• Neurology
• Neurophysiology
• Orthopedics

Background:

• Carpal tunnel syndrome (CTS) is a common condition causing median nerve compression.
• Standard electrodiagnostic tests may not detect early-stage CTS, leading to delayed diagnosis and treatment.
• Accurate early diagnosis is crucial for managing CTS and preventing irreversible nerve damage.

Purpose of the Study:

• To evaluate a novel orthodromic sensory ultra-distal test for diagnosing early-stage carpal tunnel syndrome.
• To determine if this new test can detect median nerve impairment when conventional electrodiagnostic methods yield normal results.
• To propose a new term, 'axonal carpal tunnel syndrome,' for this specific early presentation.

Main Methods:

• Studied five patients presenting with typical unilateral carpal tunnel syndrome symptoms.
• Performed standard electrodiagnostic evaluations, including needle examination (C5-T1), distal motor latency, and sensory conduction velocity.
• Utilized special tests like median-ulnar latency difference and palmar centimetric technique.
• Administered a new orthodromic sensory ultra-distal test on all median nerve digits.

Main Results:

• Standard electrodiagnostic tests and special tests were normal in all five patients.
• The novel orthodromic sensory ultra-distal test revealed significant axonal loss (60-90%) in at least two median digits.
• This finding allowed for the diagnosis of median nerve impairment, indicating early CTS.

Conclusions:

• The orthodromic sensory ultra-distal test is a sensitive method for detecting early median nerve impairment in carpal tunnel syndrome.
• This new test can identify axonal loss missed by conventional electrodiagnostic evaluations.
• The term 'axonal carpal tunnel syndrome' is proposed for this early, electrodiagnostically subtle stage of the disorder.