What are the symptoms of a pontine stroke?

Symptoms of Pontine Stroke

Pontine stroke presents with a characteristic combination of motor deficits, cranial nerve palsies, and sensory disturbances that vary based on the specific anatomical location within the pons, with horizontal gaze abnormalities being the hallmark of dorsal pontine lesions. 1

Core Clinical Presentations by Anatomical Location

Ventral (Anterior) Pontine Infarcts (Most Common)

Motor symptoms dominate ventral pontine strokes, ranging from mild to severe hemiparesis depending on medial versus lateral involvement: 1, 2

• Ventromedial syndrome: Severe hemiparesis with bilateral ataxia and dysarthria 2
• Ventrolateral syndrome: Mild hemiparesis with less prominent ataxia 2
• Associated tegmental dysfunction occurs in approximately 75% of ventral pontine strokes, though typically mild 2
• Contralateral weakness affecting face, arm, and leg due to corticospinal tract involvement 3
• Dysarthria from disruption of corticobulbar fibers 3, 4
• Ataxia and dysmetria ipsilateral to the lesion from pontocerebellar fiber disruption 3

Tegmental (Dorsal) Pontine Infarcts

Tegmental strokes present with cranial nerve deficits and sensory disturbances, with motor deficits typically mild: 1, 2

• Horizontal gaze abnormalities are the hallmark feature, including complete horizontal gaze deficit with ipsilateral facial paralysis 1, 5
• Diplopia from cranial nerve VI involvement 6
• Eye movement disorders beyond simple gaze palsy 4
• Sensory disturbances including contralateral hemibody numbness 4, 6
• Ipsilateral midfacial sensory deficits including numbness of the ala nasi, which can be an early warning sign 7
• Vertigo, dizziness, and vestibular symptoms 4
• Mild contralateral motor deficits 2, 4

Bilateral Pontine Infarcts

Bilateral pontine involvement produces devastating symptoms including locked-in syndrome: 1, 5

• Quadriplegia from bilateral corticospinal tract damage 5
• Anarthria (inability to speak) from bilateral corticobulbar tract involvement 5
• Acute pseudobulbar palsy with dysphagia 2, 4
• Transient loss of consciousness at onset 4
• Preserved consciousness and vertical eye movements in classic locked-in syndrome, as the dorsal tegmentum is spared 5

Non-Specific Posterior Circulation Symptoms

The American Heart Association emphasizes that pontine strokes frequently present with non-specific symptoms that delay diagnosis: 1

• Headache (occurs in approximately 25% of all strokes) 8
• Nausea and vomiting particularly with brainstem or cerebellar involvement 8, 1
• Dizziness and vertigo 1
• Double vision 1
• Hearing loss 1
• Imbalance 1

Critical Diagnostic Pitfalls

Truncal ataxia is the most common neurological sign missed during bedside examination and can be the only finding in patients with NIHSS score of 0 despite significant disability: 1

• The NIHSS significantly underestimates pontine stroke severity because it emphasizes limb weakness and speech over cranial nerve deficits 1
• Patients can have NIHSS of 0 despite significant posterior circulation stroke 1
• Ipsilateral midfacial sensory complaints, particularly of the ala nasi, may be an early sign of major pontine deficits and warrant urgent imaging 7

Temporal Evolution and Warning Signs

Neurological deterioration typically occurs within 72-96 hours with peak swelling, though some patients deteriorate at 4-10 days due to delayed swelling and hemorrhagic transformation: 1

• Progressive or fluctuating course is particularly associated with basilar artery branch disease and large ventral infarcts 2
• Any deviation from alert consciousness in isolated pontine stroke demands investigation for secondary complications (metabolic derangements, sepsis, medication toxicity) rather than the pontine lesion itself 9

Specific Lacunar Syndromes

Small focal pontine lesions produce restricted but recognizable clinical patterns: 3

• Ataxic hemiparesis: Combination of weakness and ipsilateral ataxia 3
• Dysarthria-clumsy hand syndrome: Speech difficulty with hand incoordination 3
• Dysarthria-dysmetria: Speech difficulty with limb incoordination 3
• Dysarthria-facial paresis: Speech difficulty with facial weakness 3

These syndromes are not absolutely discrete but distinguished by the relative degree of involvement of each clinical feature 3

Rare Presentations

Alternating deficits (ipsilateral cranial nerve palsy with contralateral motor/sensory deficits) occur in only a minority of pontine strokes and never correspond to classic textbook pontine syndromes: 2

• Higher-order impairments including motor neglect, paraphasic errors, and pathological laughter result from rostral and medial pontine lesions 3
• Unilateral multiple pontine infarcts are rare and associated with severe sensory-motor deficits and tegmental signs 4