What are the general clinical presentations of plexopathy?

General Clinical Presentation of Plexopathy

Plexopathy presents with characteristic neurological symptoms and signs that localize to an anatomically defined network of nerves called a plexus, manifesting as pain, weakness, sensory loss, and reflex changes across multiple peripheral nerve distributions.

Anatomical Context

• Brachial plexus: formed from C5-T1 ventral rami (occasionally with contributions from C4 and/or T2), with nerve roots passing between anterior and middle scalene muscles with the subclavian artery to form trunks, divisions, cords, and terminal branches 1, 2
• Lumbosacral plexus: comprised of lumbar (L1-L4) and sacral (L4-S4) plexuses connected via the lumbosacral trunk (L4-L5), formed from L1-L5 ventral rami with contributions from T12 and S1-S4 1

Clinical Manifestations

Pain Characteristics

• Neuropathic pain occurring in multiple peripheral nerve distributions (shoulder/arm or back/leg) 1
• Pain often has burning, electric, or dysesthetic quality 1, 3
• Pain is typically the initial and most prominent symptom, especially in inflammatory plexopathies 4
• Pain distribution crosses multiple dermatomes, distinguishing it from radiculopathy 1

Motor Symptoms

• Weakness in regions innervated by multiple nerves from the affected plexus 1
• Asymmetrical multifocal weakness and atrophy developing in weeks to months after pain onset 5
• Complete plexopathy causes flaccid weakness in the distribution of multiple peripheral nerves 1
• Motor deficits may not follow a single peripheral nerve or nerve root pattern 3

Sensory Symptoms

• Sensory loss across multiple nerve distributions 1
• Paresthesias, hypesthesia, and/or allodynia 5
• Sensory symptoms typically follow a non-dermatomal pattern 3
• Sensory deficits may be less prominent than motor symptoms in some plexopathies 4

Reflex Changes

• Flaccid loss of tendon reflexes in regions innervated by affected plexus 1
• Reflexes corresponding to affected nerve distributions are diminished or absent 3

Autonomic Dysfunction

• May include Horner's syndrome (ptosis, miosis, anhidrosis) in upper brachial plexopathy 6
• Other autonomic symptoms may be present depending on plexus involvement 5

Distinguishing Features by Plexus

Brachial Plexopathy

• Pain and weakness in shoulder and arm 1
• Horner's syndrome may be present, particularly in neoplastic causes 6
• Weakness and sensory loss in C5-T1 distribution 1, 2
• May present with myokymia or fasciculations on EMG in radiation-induced cases 6

Lumbosacral Plexopathy

• Pain and weakness in back, hip, and leg 1, 4
• Weakness in muscles of anterior/medial thigh (lumbar plexus) or gluteal region/posterior thigh/lower leg (sacral plexus) 1
• Sensory loss in obturator and femoral nerve territories (lumbar plexus) or gluteal, peroneal, and tibial nerve territories (sacral plexus) 1
• May present with reduced anorectal tone in severe cases involving sacral segments 7

Diagnostic Confirmation

• Clinical diagnosis confirmed by electrodiagnostic studies 1, 3
• MRI is the mainstay of plexus imaging, providing superior definition of intraneural anatomy 1
• Imaging helps distinguish between preganglionic (nerve root) and postganglionic (plexus) lesions 1
• Comprehensive electrodiagnostic testing often required due to complex plexus anatomy 3

Common Etiologies

• Traumatic: blunt force injury, penetrating injury, or iatrogenic causes 1
• Neoplastic: primary nerve sheath tumors or extrinsic invasion/compression 1, 2
• Inflammatory/immune-mediated: Parsonage-Turner syndrome (brachial neuritis), idiopathic lumbosacral plexopathy 2, 4
• Radiation-induced: typically presents with paresthesias rather than pain 6
• Diabetic: diabetic amyotrophy (Bruns-Garland syndrome) 4
• Vascular: hemorrhage or ischemia, including aneurysm rupture 7
• Infectious, hereditary, or idiopathic causes 1, 5

Clinical Course

• Varies by etiology - traumatic and neoplastic causes often progressive without treatment 3
• Inflammatory plexopathies typically follow monophasic course with slow, often incomplete recovery 4, 5
• Recovery time ranges from months to years depending on etiology and severity 4
• Neoplastic plexopathies generally present earlier after symptom onset and have shorter course compared to radiation-induced plexopathies 6