All are causes of spastic paraplegia except:

Ans: d (Fluorosis)Ref: Harrison, 17 ed. pg. 2595 Adam & Victor NeurologySACD ( B defeciency)* Subacute paraesthesia in hand & feet, spatic paraparesis, loss of posterior column sensations, optic atrophy, irritability/mental changes.Causes loss of ankle jerk with extensor plantar.Motor neuron disease* Usually presents as insidious onset assymetric weakness of distally in one of the limbs.* Progressive wasting and atrophy of the muscles with fasciculations* Exaggerated DTR with spastic weakness of the limbs in predominant corticospinal involvement* Spares cognitive functions, bowel & bladder, sensory system and ocular motility till late stages.ADEM: Clinical featuresEncephalitic form - fever, headache, confusion, convulsions, coma, decerebrate rigidity.Myelitic form -Partial or complete paraplegia/quadriplegiawith varying degree of bowel& bladder involvement.Flurosis: Even though there are case reports about fluorosis presenting as spastic paraparesis due to involvement of the spine it is very rare and hence the most possible answer here.