Bulbar palsy changes
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bulbar palsy clinical features LMN cranial nerves dysarthria dysphagia tongue
Bulbar palsy is a lower motor neuron lesion affecting motor cranial nerve nuclei or nerves, mainly CN IX, X, XI and XII, in the medulla.
Clinical changes
- Speech: dysarthria with a nasal, weak voice. Speech may become indistinct.
- Swallowing: dysphagia, nasal regurgitation of fluids, choking and aspiration.
- Palate/pharynx: palatal weakness and drooping; uvula may deviate toward the normal side. Gag reflex is reduced or absent.
- Tongue: weak, wasted (atrophic), and fasciculating. On protrusion, it deviates toward the side of the lesion in unilateral hypoglossal palsy.
- Face/jaw: lower facial weakness; difficulty chewing and managing saliva. Jaw jerk is reduced or absent.
- Secretions: drooling due to impaired swallowing.
- Respiration/nutrition: recurrent aspiration pneumonia, weight loss and respiratory compromise can occur in advanced disease.
A progressive form may be an initial presentation of motor neuron disease and can eventually involve respiratory muscles. NCBI MeSH description
Key distinction from pseudobulbar palsy:
Bulbar palsy causes flaccid weakness, tongue wasting/fasciculations, and reduced reflexes. Pseudobulbar palsy causes spasticity, brisk jaw jerk, no tongue fasciculations, and emotional lability. Bradley and Daroff's Neurology in Clinical Practice describes pseudobulbar palsy as a bilateral corticobulbar, upper motor neuron syndrome.
Bulbar palsy causes flaccid weakness, tongue wasting/fasciculations, and reduced reflexes. Pseudobulbar palsy causes spasticity, brisk jaw jerk, no tongue fasciculations, and emotional lability. Bradley and Daroff's Neurology in Clinical Practice describes pseudobulbar palsy as a bilateral corticobulbar, upper motor neuron syndrome.
Acute flaccid paralysis causes
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acute flaccid paralysis causes differential diagnosis WHO
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Causes of acute flaccid paralysis (AFP)
Acute flaccid paralysis is sudden-onset weakness with reduced tone and reflexes, usually due to pathology at the anterior horn cell, peripheral nerve, neuromuscular junction, or muscle.
1. Peripheral nerve / polyradiculoneuropathy
- Guillain-Barré syndrome: common cause; typically symmetric ascending weakness, areflexia, with possible sensory symptoms and autonomic dysfunction.
- Diphtheritic polyneuropathy
- Porphyric neuropathy
- Vasculitic neuropathy
- Tick paralysis
2. Anterior horn cell / spinal motor neuron
- Poliomyelitis: febrile onset with acute, asymmetric, predominantly proximal pure motor paralysis; sensation is preserved.
- Non-polio enteroviruses: EV-D68, EV-A71, coxsackievirus
- Acute flaccid myelitis: often follows respiratory illness in children; can cause asymmetric limb weakness and sometimes cranial/bulbar or respiratory weakness.
- West Nile virus, Japanese encephalitis
- Paralytic rabies
3. Spinal cord disorders
- Acute transverse myelitis
- Spinal cord compression: tumor, epidural abscess, hematoma, trauma
- Spinal cord infarction
- Early spinal shock after acute cord injury
4. Neuromuscular-junction disorders
- Botulism: descending paralysis with diplopia, ptosis, fixed/dilated pupils, dry mouth, and bulbar weakness.
- Myasthenia gravis or myasthenic crisis
- Lambert-Eaton myasthenic syndrome
- Neurotoxins: snake envenomation, organophosphates, aminoglycosides, magnesium toxicity
5. Muscle and metabolic causes
- Hypokalemic periodic paralysis, including thyrotoxic periodic paralysis
- Hyperkalemic periodic paralysis
- Severe hypophosphatemia or hypermagnesemia
- Acute viral myositis, polymyositis/dermatomyositis
- Rhabdomyolysis
High-yield differentiation
| Cause | Pattern suggesting it |
|---|---|
| GBS | Symmetric ascending weakness, areflexia |
| Polio/AFM | Asymmetric weakness, fever or viral prodrome, sensory sparing |
| Transverse myelitis | Sensory level plus bladder/bowel dysfunction |
| Botulism | Descending paralysis, early cranial nerve and pupillary signs |
| Myasthenic crisis | Fluctuating ocular/bulbar weakness, normal sensation |
| Hypokalemic paralysis | Acute generalized weakness with low serum potassium |
Urgent warning: AFP with dyspnea, weak cough, difficulty swallowing, pooling secretions, or rapidly progressive weakness requires emergency assessment and respiratory monitoring. WHO guidance includes polio, GBS, and transverse myelitis among key AFP differentials, with other infectious and structural causes also considered. WHO AFP guidance
The Washington Manual of Medical Therapeutics identifies GBS as a common cause of acute flaccid paralysis. Harrison’s describes acute flaccid myelitis as an anterior-horn-cell syndrome that progresses over hours to days and may affect bulbar or respiratory muscles.
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