Table 3.

The differences among the various subtypes of palatal tremor.

	Essential Palatal Tremor (EPT)	Symptomatic Palatal Tremor (SPT)	Progressive ataxia with Palatal Tremor (PAPT)
Main muscle involved in the generation of tremor [3,23]	Tensor veli palatini	Levator veli palatini	Levator veli palatini
Nerve supply of the main muscle [3,23]	5%th cranial nerve	9%th and 10%th cranial nerves	9%th and 10%th cranial nerve
Abnormal reflex types [23]	Polysynaptic	Monosynaptic, oligosynaptic and polysynaptic	Not known
Relationship with sleep [23]	Disappears in 50% cases	Persists	Persists
Effect of anaesthesia on tremor	disappears	persists	Not known
Auditory signs	Audible ear click -Common	Audible ear click-rare	Tinnitus, sensorineural hearing loss Audible ear click – rare (familial)
Ocular signs	Rare	Can be seen	Torsional and horizontal nystagmus, INO, hypermetric saccades, reduced VOR, vertical gaze palsy, optic atrophy
Other clinical features	Rare except the ear click, entrainment common	Ataxia, tremor, dysarthria etc – not entrainable	Familial PAPT – additional pyramidal tract signs like tetraparesis, progressive ataxia, chorea, dystonia, cognitive impairment, autonomic dysfunction, tendon xanthoma Sporadic PAPT: dysarthria, dysphagia
Cause	Unknown	Sporadic -any Lesion (infarct, bleed, tumour etc) within the Guillain Mollaret triangle of brainstem or idiopathic/neurodegenerative	Familial/genetic – (POLG mutation, Alexander disease, Celiac disease, Cereberotendinous Xathomatosis, Celiac disease, GM2 Gangliosidosis) Neuroferritinopathy Sporadic-Neurodegenerative/tauopathy/MSA/Gluten sensitive
Magnetic resonance imaging of brain	No structural deficit	Hypertrophic olivary degeneration of medulla	Familial -significant brainstem atrophy but no HOD, dark dentate nucleus, cerebellar atrophy, iron accumulation in basal ganglia (Neuroferritinopathy) White matter lesion with frontal predominance (Alexander disease) Sporadic PAPT-HOD