NPTE - PNS Disorders

PNS Anatomy

CNs 3-12, spinal nerves, and the peripheral nerves

Motor (efferent) and sensory (afferent) fibers

Lesions cause LMN signs

LMN signs

Flaccid paralysis

Mm atrophy

Fasciculations

Hyporeflexia

Hypotonia

Neurapraxia

Mild injury, myelin damage only

full recovery within weeks

Axonotmesis

axonal damage, intact endoneurium

recovery via axonal regrowth

Neurotmesis

Complete nerve severance

Requires surgery, poor prognosis

Boards Tip Pt 1

Neurapraxia = temporary block (Saturday Night Palsy)

Neurotmesis = worst

Common PNS Disorders

GBS

Charcot-Marie-Tooth Disease

MG

Post-Polio Syndrome

Bell’s Palsy

Trigeminal Neuralgia (CN V)

GBS Pathophys

Autoimmune, demyelinating polyneuropathy

Rapid ascending weakness (LE —> UE), areflexia

Often follows infection/vaccination

No cognitive involvement

PT Role in GBS

Avoid overfatiguing!

Focus on respiratory care, PROM —> AAROM —> strengthening

Progress slowly with functional tasks

GBS Outcome Measures

FIM

MMT

Vital Capacity

Charcot-Marie-Tooth Disease

Genetic, progressive polyneuropathy

Weakness in distal LE > UE, foot drop, pes cavus

Sensory loss may occur

PT Role in Charcot-Marie-Tooth

Orthotic management (AFO)

Balance and gait training

Avoid overwork weakness

MG

Autoimmune, affects the NM junction (ACh receptors)

Fluctuating weakness, worse with activity, better with rest

Affects face, eyes, speech, and swallowing (ptosis, dysphagia)

PT Role in treating MG

Energy conservation, pacing

Respiratory monitoring

Avoid heat, overexertion

What test is used to confirm MG dx?

Tensilon Test

Post-Polio Syndrome

Occurs years after the initial polio infection

Progressive new weakness, fatigue, joint pain

PT Role in Post-polio syndrome

Avoid overuse

Submaximal exercise, orthoses, pacing

Energy conservation and adaptive strategies

Bell’s Palsy

LMN lesion of the Facial Nerve (CN VII)

Sudden, UL facial paralysis

Often idiopathic/post-viral

PT Role in Bell’s Palsy

Facial exercises, massage, and eye protection

E-stim is controversial

Differentiate Bell’s Palsy from a stroke

Bell’s palsy = entire face

Stroke = lower face only

Trigeminal Neuralgia (CN V)

Sudden, severe facial p! (jaw, cheek)

Often triggered by light touch, chewing

PT Role in Trigeminal Neuralgia

Ed on triggers, desensitization strategies

Modalities for p! control

Median Nerve Entrapment

Entrapment at Carpal tunnel

S&S: numbness in thumb-3rd digit, atrophy

Tx: splinting, ergonomic training

Ulnar Nerve Entrapment

Entrapment at Cubital Tunnel, Guyon’s Canal

S&S: claw hand, sensory loss

Tx: activity mod, ulnar glides

Radial Nerve Entrapment

Entrapped at the spiral groove (humerus)

S&S: Wrist drop

Tx: dynamic splint, strengthening

Peroneal Nerve Entrapment

Entrapped at the fibular head

S&S: foot drop

Tx: AFO, gait training

Tarsal Tunnel Entrapment

Entrapped post to med mall

S&S: foot p!, tingling

Tx: orthotics, activity modification

Diagnostic Tests

EMG - evals motor unit ftn

Nerve Conduction Study - assesses speed and amplitude of signals

Tensilon test - dx MG

Lumbar puncture - high protein in GBS

PT Interventions for PNS disorders

ROM and contracture prevention (esp in flaccid limbs)

Orthotics for foot drop/hand ftn

Task-specific gait training

Fatigue management: GBS, post-polio, MG

Sensory re-ed for sensory loss

NM re-ed for motor control

Avoid overwork weakness in chronic NM disorders!

Red flags for PNS disorders

Rapidly ascending weakness —> GBS —> hospital referral

Respiratory weakness/fatigue —> emergency (MG, GBS)

Unexplained new weakness years after polio —> post-polio

B facial weakness/eye involvement —> refer for neuro eval

Boards Tips Pt 2

PNS = LMN signs (hypotonia, decreased reflexes, atrophy, fasciculations)

Know the difference btw myopathy and neuropathy

MG = fatigue worsens with activity

GBS = careful not to over-fatigue during rehab

Foot drop = peroneal nerve injury/CPN entrapment

Stroke spares the upper face; Bell’s Palsy affects the whole face

Myopathy

Disease/dysfunction of mm fibers

Mm itself is weak

Proximal > distal (shoulders, hips)

Typically normal/slightly decreased reflexes

Sensation intact

Mild mm atrophy (late stage)

Typically normal tone

No fasciculations

Short-duration, low-amplitude APs on EMG

Ex: MD, polymyositis, statin-induced myopathy

Neuropathy

Disease/famage of the peripheral nerves

The nerve signal to the mm is disrupted

Distal > proximal (hands, feet)

Decreased/absent reflexes

Sensation often impaired (N&T)

Mm atrophy is more pronounced, often early

Often hypotonia with LMN lesions

Fasciculations present (esp in LMN neuropathies)

Fibrillations, sharp waves, abnormal MUs on EMG

Ex: GBS, diabetic neuropathy, CTS

If a pt has distal weakness, numbness, absent reflexes, and fasciculations

they probably have neuropathy

If a pt has proximal weakness, normal sensation, and intact reflexes

they probably have myopathy