Pronator drift (Barre's sign)

Mô tả: There is asymmetric downward arm movement when the patient extends both arms upright in the supinated position (e.g. palms straight up) with the eyes closed and is asked to hold them completely still. Downward arm drift, forearm pronation and flexion of the wrist and elbow typically begin distally and progress proximally.18 RELEVANT NEUROANATOMY AND TOPOGRAPHICAL ANATOMY

Nguyên nhân: Common • Cerebral infarction • Cerebral haemorrhage • Cervical cord lesion Less common • Lacunar infarction, posterior limb internal capsule • Multiple sclerosis • Mass lesion (e.g. tumour, abscess, AVM) Pronator drift 379 Internal capsule Pyramidal tract Cerebral peduncle Corticobulbar tract VII XII IX X II Pyramid Pyramidal tract Decussation of pyramidal tract Lateral corticospinal tract Spinal cord Medulla Medulla Midbrain Tongue Jaw Lips Face Brow Thumb Hand Wrist Elbow Shoulder Trunk Hip Knee Ankle Toes Pons

Cơ chế: When visual cues are removed, subtle upper motor neuron weakness causes the weak limb to drift downward.

Ý nghĩa lâm sàng: Pronator drift is a more sensitive test than power testing alone to detect upper motor neuron weakness.4,18 Refer to Table 5.27 for clinical utility.