CLINICAL DIAGNOSTIC MANUAL
Weakness of some small muscles in the hand can significantly affect dexterity and the ability to perform fine tasks. This weakness can be caused by various pathologies affecting peripheral nerves, nerve roots, or even the central nervous system.
The intrinsic muscles of the hand are crucial for fine motor function, and any injury compromising these muscles can have a noticeable impact on the patient’s quality of life. Identifying the underlying cause requires a detailed clinical evaluation and appropriate complementary tests.
Condition | Clinical Symptoms and Signs | Suspected Diagnosis | Confirmatory Diagnosis |
Median nerve palsy | Weakness in thenar muscles, difficulty opposing the thumb, thenar atrophy, sensory loss in the thumb, index, and middle fingers | Clinical history, physical exam, Phalen’s and Tinel’s tests | EMG, nerve conduction studies |
Ulnar nerve lesion | Weakness in interosseous and lumbrical muscles, claw hand posture, hypothenar atrophy, sensory loss in the little finger | Clinical history, physical exam, specific signs of ulnar nerve | EMG, nerve conduction studies |
T1 level lesion | Weakness and atrophy of hand muscles, loss of reflexes, possible Horner’s syndrome | Clinical history, neurological exam | Cervical spine MRI, nerve conduction studies |
Motor neuron disease | Progressive weakness, muscle atrophy, fasciculations, multiple muscle groups involved | Clinical history, neurological exam | EMG, nerve conduction studies, brain MRI |
Syringomyelia | Weakness and atrophy of hand muscles, dissociated sensory loss (pain and temperature) | Clinical history, neurological exam | Cervical spine MRI |
Prolonged systemic illness | Generalised weakness, muscle atrophy, signs of chronic disease (anaemia, weight loss) | Clinical history, physical exam, systemic symptoms evaluation | Laboratory tests (CBC, renal and liver function) |
Cervical spondylosis | Weakness and atrophy of hand muscles, neck pain, radiculopathy, paraesthesias | Clinical history, neurological exam | Cervical spine MRI, X-rays |
Compressive nerve root tumour | Weakness and atrophy of hand muscles, radicular pain, loss of reflexes, paraesthesias | Clinical history, neurological exam | Cervical spine MRI |
Brachial plexus injury | Weakness and atrophy of hand and arm muscles, loss of reflexes, paraesthesias, pain | Clinical history, neurological exam | EMG, nerve conduction studies, brachial plexus MRI |
Cervical rib | Weakness and atrophy of hand muscles, paraesthesias, neck and shoulder pain | Clinical history, physical exam, Adson’s test | Cervical spine MRI, X-rays |
Pancoast tumour | Weakness and atrophy of hand muscles, shoulder pain, Horner’s syndrome, cough, weight loss | Clinical history, physical exam, systemic signs | Thoracic MRI or CT, biopsy if necessary |
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