The tongue may be affected by a number of neurologic disorders. The appearance of the tongue may suggest the cause. The bulbar nuclei refer to the nuclei in the brainstem for Cranial Nerves IX to XII.
(1) hypoglossal nerve (Cranial Nerve XII) paralysis
(2) bulbar palsy (associated with a lower motor neuron disorder)
(3) pseudobulbar palsy (associated with an upper motor neuron disorder)
(1) deviation of the tongue
(2) wasting of the tongue
(3) weakness of the tongue
(5) other findings (dysphagia, dysarthria, facial weakness)
Unilateral hypoglossal nerve paralysis is associated with:
(1) deviation of the tongue tip towards the side of the affected nerve (to the patient's left indicates left hypoglossal nerve, to the patient's right indicates the right hypoglossal nerve)
(2) wasting of the tongue on the same side as the deviation
(3) muscle fasciculations
(4) weakness on the affected side
Bilateral hypoglossal nerve paralysis would not show a deviation and the whole tongue would show wasting.
Bulbar palsy is associated with:
(1) no tongue deviation
(2) no tongue wasting
(5) dysphagia, dysarthria and facial weakness
Pseudobulbar palsy is associated with:
(4) no fasciculations
(5) dysarthria with normal gag reflex
Differential diagnosis of tongue deviation without other change:
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