Flaccid Paraparesis

Routine for examination of lower limbs:


Inspect (wasting, fasciculations, wheelchair/walking aid, catheter, pes cavus, limb shortening, inverted champagne bottle appearance)

Gait and Rhomberg’s test




Sensation (sensory level, joint position sense and vibration)



If time allows and you suspect flaccid paraparesis proceed as follows:


Back: sacral dimple, tuft of hair, scoliosis

Face: test CN VII, observe for ptosis, test eye movements, test fatiguability

Hands: wasting, coordination




Present to the examiner:


This patient has a flaccid paraparesis as evidenced by:


Reduced tone bilaterally

Wasting and weakness bilaterally

Reduced/absent reflexes

Mute/downgoing plantars


The patient was (un)able to walk. There was a wheelchair/walking aid by the bedside

There was (no) sensory loss

There were (no) cerebellar signs


With regards to aetiology:


There were (no) fasciculations to suggest motor neuron disease

There was (no) limb shortening to suggest polio

There was (no) sensory level to suggest cauda equina syndrome

There was (no) evidence of pes cavus and/or inverted champagne bottle appearance and/or scoliosis and/or hand muscle wasting to suggest charcot-marie tooth disease

There was (no) ptosis, opthalmoplegia, facial weakness to suggest guillain-barre syndrome or myasthenia gravis

There was (no) fatiguability to suggest myasthenia gravis

There were (no) cutaneous signs of spina bifida


To complete my examination I would like to:


Ask about bladder and bowel function

PR examination (if sensory level)

Assess speech and swallow and Forced vital capacity

Perform full neurological examination of upper limbs and cranial nerves (if not already done)



Causes of Flaccid Paraparesis:


*Think anterior horn cell—nerve root—plexus—peripheral nerve—NMJ—muscle*


  1. Anterior horn cell disease e.g. motor neuron disease (NB: mixed upper and lower motor neuron signs), poliomyelitis
  2. Cauda Equina Syndrome secondary to disc herniation/epidural abscess/mets/haematoma etc.
  3. Lumbosacral plexopathy secondary to trauma/tumour/abscess (usually unilateral)
  4. Motor neuropathies:
    1. Inflammatory: guillain-barre syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy, sarcoid, vasculitis, paraprotein, amyloidosis
    2. Infectious: HIV, diphtheria, lyme disease, HTLV-1, west nile virus, rabies, enteroviruses
    3. Toxins: lead, arsenic, thallium, mercury, shellfish, pufferfish poisoning
    4. Metabolic: diabetic amyotrophy, porphyria
    5. Drugs: ciclosporin, gold, penicillamine
    6. Congenital: charcot marie tooth disease (HSMN)
  5. Neuromuscular junction disorders:
    1. Myaesthenia gravis
    2. Lambert-Eaton myaesthenic syndrome
    3. Botulism
    4. Organophosphate poisoning
    5. Tick paralysis
    6. Snake venom
  6. Myopathies:
    1. Inflammatory: polymyositis/dermatomyositis. NB: can overlap with other connective tissue disease eg mixed connective tissue disease
    2. Other connective tissue disease eg. SLE, vasculitis, RA, systemic sclerosis.
    3. Cancer (paraneoplastic: carcinomatous neuromyopathy)
    4. Drugs (statins, steroids)
    5. Infections (bacterial infections, HIV, CMV, EBV, Hepatitis)
    6. Endocrine (thyroid, addisons, osteomalacia, cushings, acromegaly, diabetic amyotrophy)
    7. Toxins (alcohol)
    8. Metabolic (renal/liver failure, electrolyte disturbance e.g. periodic paralysis)
    9. Miscellaneous (inclusion body myositis, rhabdomyolysis, sarcoidosis, mitochondrial myopathy, muscular dystrophy)
  7. Miscellaneous:
    1. Spina Bifida (lumbosacral lesion)



Investigations according to most likely cause:



Spirometry (FVC), ABG, CXR

EMG and Nerve conduction studies looking at velocity and amplitude

Bloods: peripheral neuropathy screen (see “Station 3 Peripheral Neuropathy”), CK, anti-AChR, anti-ganglioside antibodies

Neuro imaging (exclude cauda equine syndrome)

Lumbar puncture to examine CSF (raised protein in guillain-barre for example)

Genetic testing

Nerve biopsy

Muscle biopsy




Hereditary Sensory Motor Neuropathy (Charcot Marie Tooth Disease):


Inherited peripheral neuropathy (motor>sensory)

Autosomal dominant mainly

CMT type 1. Chromosome 17. Mutation in PMP22 gene. Demyelination (reduced velocity on nerve conduction studies).

Causes distal wasting of legs (inverted champagne bottle appearance) and hands (clawed appearance) with weakness and mild sensory loss (can have sensory ataxia with positive Rhombergs) and areflexia. Bilateral foot drop with high-stepping gait. Bilateral pes cavus and toe clawing. Scoliosis. Occasionally palpable peripheral nerves.

Management: Multidisciplinary (physio, OT, geneticist, neurologist, orthopaedics, orthotics), analgesia, orthopaedic procedures


Guillain-Barre Syndrome (GBS):


An acute inflammatory demyelinating polyneuropathy

Onset over days- weeks. Following infection (often respiratory eg. M. pneumoniae/diarrhoeal illness eg. campylobacter)

Spinal pain, distal paraesthesiae, fatigue, ascending flaccid limb weakness, areflexia. Sensory deficits usually mild/patchy.

Also affects:

Cranial Nerves: ptosis, opthalmoplegia, facial nerve, bulbar weakness

Autonomic: tachycardia, labile BP, arrhythmias, bladder and bowels

Resp: SOB and fatigue.

NB: miller-fischer syndrome is a proximal variant of GBS causing ataxia, opthalmoplegia, areflexia (anti-GQ1b antibodies)

Can also get a sensory variant of GBS.


Investigations: albuminocytological dissociation in CSF (raised protein with normal WCC), reduced velocity and conduction block on NCS, antibodies to gangliosides (anti-GM1), vital capacity, ECG

Management: ITU if vital capacity <1.3L/bulbar dysfunction. May need tracheostomy, NGT. Give IVIG +/- methylprednisolone, or plasma exchange.

Becomes chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) if doesn’t cease by 6 weeks.


Cauda Equina Syndrome:


Compressed lumbosacral nerve roots below the level of the cord (disc herniation, trauma, tumour, abscess, inflammation, spinal stenosis for example)

Causing low back pain, sciatica, saddle anaesthesia, bladder and bowel and sexual dysfunction, flaccid paraparesis and areflexia.

Urgent MRI



Spina Bifida:


Asymmetrical flaccid paraparesis with associated sensory loss (often L5, S1) and bladder/bowel involvement. Cutaneous signs of spina bifida include tufts of hair, dimples.

Neural Tube defect (incomplete closure of vertebral canal). Folic acid deficiency and sodium valproate use in pregnancy.


Old Polio:


Flaccid monoparesis. Often associated limb shortening. No sensory loss. Differential = infantile hemiplegia

Polio is an enterovirus. Faecal-oral route of transmission. Predilection for anterior horn cells. Vaccine now exists.



Differential diagnosis of pes cavus (indicating long standing problem):


Charcot Marie Tooth disease

Spina bifida


Friedreich’s ataxia


Cerebral palsy

Muscular dystrophy



Written by Dr Sarah Kennedy


Resources used to write this document are listed in the references section of this webpage