Cheiro- Oral Syndrome.
Cheiro- oral syndrome (COS) is a rare variant of thalamic stroke syndromes, with sensory impairment involving the fingers and the perioral regions. COS is classified into four classes based on clinical manifestations. Class I is characterized by sensory disturbance of the face and hand or fingers contralateral to the brainstem or thalamic lesion. Additional types include COS with bilateral sensory impairment (Class II), bilateral symptoms in the perioral region and unilateral symptoms in the hands and fingers, or vice versa (Type III), and crossed Cheiro-Oral syndrome (Type IV) with perioral symptoms on one side of the body and upper extremity symptoms on the contralateral side. Efferent (ocular motor) or afferent (visual loss) can arise in COS from involvement of proximal structures to the thalamus.
Ischemic or hemorrhagic strokes are often cited as frequent causes of COS, other structural lesions have been implicated including tumors, subdural hematomas, aneurysms, and encephalitis.
Sensory deficits around the corner of the mouth as well as in the ipsilateral upper extremity occur commonly due to the close mapping of the sensory homunculi regions in the thalamus, namely the ventral posterior medial and ventral posterior-lateral regions, but also the spinothalamic and the trigeminothalamic tracts in the brainstem. In addition, oculomotor or visual deficits can arise due to ischemia in proximal neuroanatomical regions. 
|Localization of Lesion||Presentation|
|Midbrain, Medial Longitudinal Fasciculus||Internuclear Ophthalmoplegia|
|Tegmentum of Midbrain||Nystagmus or Ocular Motor Nerve Palsy|
Ischemia to the various thalamic nuclei occurs via small penetrating vessels originating from the posterior circulation vessels and larger parent vessels including the basilar, posterior cerebral, and posterior communicating arteries may cause optic tract abnormalities. Lesions of the optic tract posterior to the chiasm cause contralateral homonymous visual field defects in both eyes. Optic tract lesions produce either a complete or incomplete incongruous homonymous hemianopia and often a specific pattern of optic disc pallor. Optic tract lesions may produce a relative afferent pupillary defect (RAPD) because the pupillomotor fibers decussate unequally in the chiasm and travel in the optic tract before exiting at the brachium of the superior colliculus.
Neurologic examination can reveal sensory deficits to pain and discriminative touch over the perioral region and the fingers. Initial computed tomography (CT) scan of the head may show hypodensity consistent with an acute ischemic infarct, a hemorrhage, or other structural lesion of the thalamus. CT angiography (CTA) is also an important rapid assessment of large vessel occlusion and may also be effective for the detection of medium and small vessel occlusions in COS. Cranial magnetic resonance imaging (MRI) can confirm ischemia or other lesions causing COS. Diffusion-weighted imaging (DWI) in MRI is highly sensitive and specific for diagnosing acute stroke.  A full stroke work up is generally recommended for patients with COS due to ischemia.
Neuroimaging can confirm the location and etiology of COS and treatment should be directed towards the underlying etiology. Management of vascular risk factors, as ischemic heart disease, hyperlipidemia, hypertension, diabetes mellitus, and smoking, is the most important factor that will help preventing future infarctions. 
The outcome of COS is variable but often good especially in those with subcortical lesions. Lin et al. noted that only 14 of 85 (16.5%) patients had deterioration or progression of symptoms in the acute period. However, lesions caused by subdural hematomas and brainstem infarcts portend a worse prognosis. 
The cheiro-oral (COS) syndrome is an uncommon neurologic condition characterized by sensory disturbances of the peri-oral area and the upper extremity (hand or fingers) and due to a contralateral thalamic lesion. Most cases of COS are caused by ischemic or hemorrhagic strokes but other lesions of the thalamus producing COS include tumors, subdural hematomas, aneurysms, and infections.
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