Day 4 - Weakness

Generalized:

• Fatigue

• Hyper/

  hypothyroidism

• Infection/Sepsis

• Anemia

• Heart failure

• Arrhythmia

• PMR

• Depression

• Adrenal insufficiency

Lower Motor Neuron:

• Guillain-Barre Syndrome

• CIDP

• Polyneuropathy

• Radiculopathy

• *ALS

Upper Motor Neuron:

• Stroke

• Tumour

• Cord compression

• Multiple sclerosis

• *ALS

Neuromuscular Junction:

• Myasthenia Gravis

• Botulism

• Lambert Eaton Syndrome

Muscle:

• Dermatomyositis

• Polymyositis

• Rhabdomyositis

• Muscular dystrophy

History:

• Probe what patient means by “weakness”

  • Often can mean generalized fatigue, dyspnea, presyncope, pain or true decrease in limb strength

• Assess onset and duration

  • Acute vs chronic

  • Constant vs intermittent vs fatiguable

• Preceding or associated symptoms

  • Recent illness

  • Constitutional symptoms (weight loss, fevers, sweats, chills)

  • Trauma

  • Pain vs loss of sensation

  • Paresthesias

  • Visual disturbances

  • Saddle anaesthesia, urinary retention, fecal incontinence

• Localize weakness

  • Proximal vs distal muscles

  • Single limb vs multiple

  • Symmetrical vs asymmetrical

  • Bulbar dysfunction

  • Respiratory muscle weakness

Physical Exam:

• Full neurological examination

  • Strength testing in all limbs

  • Tone - increased suggests UMN, decreased LMN

  • Reflexes - increased in UMN, decreased in LMN

  • Muscle wasting - present in UMN, muscle bulk generally maintained in LMN

  • Sensation - use to determine sensory level

  • Fasciculations - absent in UMN, present in LMN and ALS (presents with UMN & LMN findings)

Investigations:

• Guided by exam & clinical suspicion

• MRI spine for potential cord compression

• CT/MRI brain

• Lumbar puncture

• EMG (weakness must have been present for at minimum 2 weeks to see changes)

• CBC, electrolytes, extended electrolytes, TSH/T4, CK, blood cultures, ECG, anti-acetylcholine receptor antibody