Brown-Séquard syndrome (hemisection)

•    Ipsilateral (same side):

o    Weakness (UMN signs below lesion: spasticity, hyperreflexia).

o    Loss of vibration and proprioception (dorsal column).

•    Contralateral (opposite side):

o    Loss of pain and temperature sensation (spinothalamic tract, crossing at entry level).

•    Causes:

o    Trauma (e.g., stab wound).

o    Spinal tumors.

o    Demyelination (MS).

Motor Neurone Disease (MND)

•    Amyotrophic Lateral Sclerosis (ALS) = most common subtype.

•    Key features:

o    Mixed UMN (spasticity, brisk reflexes, upgoing plantars) and LMN (wasting, fasciculations, weakness) signs.

o    No sensory symptoms.

o    Often affects limbs asymmetrically → "split hand sign" (wasting of lateral hand muscles with sparing of medial).

•    Bulbar signs:

o    Dysarthria, dysphagia, tongue fasciculations.

o    "Pseudobulbar affect" (emotional lability).

•    Respiratory involvement:

o    Weakness → respiratory failure is common terminal event.

•    Treatment:

o    Riluzole (glutamate inhibitor) → modestly prolongs survival (~3 months).

o    Symptomatic support (non-invasive ventilation improves survival and QoL).

•    Variants:

o    Progressive muscular atrophy (pure LMN).

o    Primary lateral sclerosis (pure UMN).

o    Progressive bulbar palsy.

"Absent reflexes + extensor plantars" clue

•    Suggests mixed UMN and LMN pathology, classic in:

o    MND.

o    Subacute combined degeneration (if also B12 deficiency, but would have sensory loss).

Spinal cord vascular syndromes

Anterior spinal artery infarct

•    Motor loss below lesion:

o    Bilateral weakness (corticospinal tract).

•    Loss of pain and temperature below lesion:

o    Spinothalamic tract involvement.

•    Sparing of vibration and proprioception:

o    Dorsal columns supplied by posterior spinal arteries.

•    Common causes:

o    Aortic dissection.

o    Severe hypotension.

o    Vasculitis.

Posterior cord syndrome

•    Rare.

•    Loss of vibration and proprioception below lesion.

•    Motor and pain/temp usually spared.

Extra Revision Pearls

•    ALS clue: "No sensory loss despite severe weakness → think MND."

•    Bulbar vs pseudobulbar:

o    Bulbar (LMN): tongue wasting, fasciculations.

o    Pseudobulbar (UMN): spastic tongue, brisk jaw jerk, emotional lability.

•    Brown-Séquard clue: "Crossed sensory findings + unilateral weakness."

•    Anterior spinal artery infarct clue: "Can't move or feel pain/temp below lesion, but still sense vibration."

•    "Split hand sign" in ALS: selective atrophy of lateral hand muscles (thenar, first dorsal interosseous).