PARAPARESIS:
There are two types of bilateral lower limb weakness; upper motor ( spastic) type or Lower motor ( Flaccid) type or Combination of signs.
Upper motor ( spastic) means Hypertonia & hyper reflexia with up going planters. Lesions either in Thoracic cord or above. Wasting, fasciculations or absent ankle jerks are Not feature of upper motor lesions.
If upper limbs are normal along with spastic paraparesis it’s thoracic cord.
If upper limbs are flaccid( lower motor weakness) along with spastic paraparesis,then it’s Cervical cord from C5-T1.
If upper limbs are also spastic( upper motor type) along with spastic parapresis,then lesion is above C5. Now check for cranial nerves . If cranial nerves notmal its upper cervical cord.if 9,10,11 or 12 involved spastic tongue & jaw jerk, lesion in medulla. If 5,6,7,8 are involved lesion is in Pons. If 3,4 involved lesions in Mid brain.
If upper limbs & Cranial nerves both are also spastic along with spastic Paraparesis then it’s PseudoBulbar Palsy ( bilateral lesion above mid brain) & causes can be Bilateral cortical or internal capsule infarcts, MND, Progressive supra nuclear palsy etc. clues for spastic cranial nerves will be exaggerated jaw jerk & stiff tongue & stiff palate etc.
FLACCID PARAPARESIS ( Lower motor type weakness). Absent reflexes, hypotonia, wasting, fasciculations etc are the signs.
If flaccid Paraparesis with sphincter involvement it’s either lumbar spinal cord disease or cauda equina syndrome. Later never involved L1 area & also the deficit of sensations/weakness is patchy due to displacement of some of the roots & compression of the remaining roots in cauda equina.
If flaccid Paraparesis without sphincter involvement then it’s unlikely to be cauda equina or lumbar cord. Then if acute & without wasting think acute polyradiculopathy like GB syndrome. If chronic with wasting then think CIDP. If associated with pes cavus then think of long standing neuropathy like Charcoat Marie Tooth Diseade.If chronic with motor and sensory loss below Knees it’s peripheral neuropathy. If pure motor loss with wasting but without any sensory finding think of MND which usually has fasciculation or Multifocal motor axonopthy which is usually asymmetrical.
If spastic Paraparesis mixed with signs of flaccid ( likd absent ankle jerk or wasting or fasciculations etc) think of disease which can involve both the cord & peripheral nerves;
- Cord disease with Neuropathy
- Subacute combined degeneration ( B12 defi)
- Neurosyphilis ( Tabes Dorsalis)
- If pure motor signs, no sensory findings its MND
5.Meningoradiculopathy due to chronic meningitis of spinal cord level. - Spinocerebellar degeneration ( usually has Pes cavus )