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N10 Neurology
Approach to Common Presentations
Toronto Notes 2019
Central Motor Systems
3 components to the control of gait:
• Pyramidal: main outflow from cortex to spinal cord
• Extrapyramidal: basal ganglia inhibits excess movements
• Cerebellum: affects coordination of gait
Differential Diagnosis
• objectivemuscleweakness;also,differentiatebetweentruemuscleweaknessvs.fatigue ■ generalized
◆ myopathy (proximal > distal weakness)
– endocrine: hypothyroidism, hyperthyroidism, Cushing’s syndrome
– rheumatologic: polymyositis, vasculitis
– infectious: HIV, influenza
– other: collagen vascular disorders, steroids, statins, alcohol, electrolyte disorders
◆ NMJ (MG, botulism, LEMS, organophosphate poisoning)
◆ cachexia ■ localized
◆ UMN (vasculitis, abscess, brain tumour, vitamin B12 deficiency, MS, stroke)
◆ radicular pain (i.e. nerve root)
◆ anterior horn cell (spinal muscular atrophy, ALS, polio, paraneoplastic, lead toxicity)
◆ peripheral neuropathy (peroneal muscle atrophy, GBS, leprosy, amyloid, myeloma, DM, lead
toxicity)
• noobjectivemuscleweakness
■ chronic illness (cardiac, pulmonary, anemia, infection, malignancy) ■ depression, deconditioning
Numbness/Altered Sensation
Approach
• positivesensorysymptoms:paresthesia/dysesthesia=tingling,pinsandneedles,prickling,burning, stabbing
• negativesensorysymptoms:hypoesthesia/anesthesia=numbness,reduction/absenceoffeeling
• determinedistributionofsensoryloss:
■ nerve root vs. peripheral nerve
■ symmetric stocking-glove pattern (indicative of distal symmetric polyneuropathy)
■ dissociated sensory loss: dorsal column (fine touch, proprioception, vibration) vs. spinothalamic
tract (pain and temperature)
• investigations:NCS,bloodglucose,vitaminB12levels,imagingbasedonassociatedfindings
Differential Diagnosis
• cerebral: stroke, demyelination, tumour
■ associated symptoms: hemiplegia, aphasia, apraxia
• brainstem: stroke, demyelination, tumour
■ associated symptoms: diplopia, vertigo, dysarthria, dysphagia, crossed sensory and/or motor
findings
• spinalcord/radiculopathy:cordinfarction,tumour,MS,syringomyelia,vitaminB12deficiency,disc
lesion
■ associated symptoms: back/neck pain, weakness (paraparesis or Brown-Séquard pattern)
• neuropathy:focalcompressiveneuropathy(basedonlocationanddistribution),DM,uremia,vasculitis, vitamin B12 deficiency, HIV, Lyme disease, alcohol, paraneoplastic, amyloid
Gait Disturbance
Approach
1. Characterization of the gait disturbance
■ posture, stride length, width between feet, height of step, stability of pelvis, symmetry, arm swing, difficulty turning, tremor, elaborate/inconsistent movements, standing from sitting
2. Identification of accompanying neurologic signs
■ full neurological exam required (diagnosis often can be made by P/E alone)
3. Identify red flags
■ sudden onset, cerebellar ataxia, paresis (hemi-, para- or quadri-), bowel/bladder incontinence
4. Workup
■ based on etiology – requires blood work, neuroimaging, and urgent neurologist referral