ventral pons (perforating branches of basilar artery)
corona radiata (small MCA branches)
cerebral peduncle (small MCA branches)
Pure sensory syndrome
contralateral loss of all primary sensory modalities
localization:
ventral posterior lateral (VPL) nucleus of the thalamus (thalamoperforator branches of the PCA)
Sensorimotor stroke
unilateral face/arm/leg weakness (with or without dysarthria)
contralateral loss of all primary sensory modalities
localization:
posterior limb of the internal capsule and thalamic VPL or thalamic somatosensory radiations (thalamoperforator branches of the PCA, or lenticulostriate arteries)
Basal ganglia lacune
often asymptomatic, but may cause hemiballismus
localization:
caudate nucleus, putamen, globus pallidus, or subthalamic nucleus (lenticulostriate, anterior choroidal, thalamoperforator, or Heubner's arteries)
Brainstem Syndromes
There are more than 25 named brainstem stroke syndromes
many are rare
descriptions in clinical literature may be inconsistent
many were described before the MRI era
some of them might not exist...
... in a study of 245 patients with MRI-confirmed brainstem strokes, only 19 had a "classic" brainstem stroke syndrome (14 of those were Wallenberg) - Marx, J. J., & Thömke, F. (2009). J of Neurology, 256(6), 898–903.
Brainstem lesions classically produce "crossed deficits"
...the reason to learn brainstem syndromes is to understand neuroanatomy, not because they are commonly encountered in clinical practice!
Thalamic Syndromes
There are 4 major thalamic vascular territories (figure 1)(figure 2)
Tuberothalamic artery - arises from middle third of PComm
Paramedian artery (of Percheron) - the superior ramus of the interpeduncular branches of P1 segment of PCA (middle and inferior branches supply midbrain and pons) - bilateral branches may arise from a single common pedicle
Inferolateral artery - 5 to 10 branches arising from the P2 segment of the PCA, supply lateral regions of thalamus
Posterior choroidal artery - also arise from P2, except for one or two branches that may arise from distal P1
Vascular syndromes of the thalamus (table)
Cases
Case One
80 yo F with PMHx of A. Fib, HTN, T2DM, dyslipidemia, obesity
acute onset of confusion, decreased movement of left arm and leg
Examination
Awake, inattentive, not following commands consistently, no aphasia or dysarthria
Left homonymous hemianopsia
Left-sided sensory loss
Left hemineglect
Left hemiparesis (uncertain due to neglect)
Left extensor plantar response
Imaging
CT Scan
Case Two
87 yo F with PMHx of A. Fib, HTN, dyslipidemia, obesity
Presented to ER 2 hours from symptom onset with speech difficulty, right-sided weakness
Examination (at presentation)
Awake, follows commands
Expressive (Broca) aphasia and severe dysarthria
Right-sided homonymous hemianopsia
Severe right-sided UMN facial weakness
No movement of right arm, anti-gravity only of right leg
Right extensor plantar response
treated with IV tPA in the emergency department
symptoms improving the next day, with improvement of language but ongoing right-sided weakness
Imaging (the next day, post-tPA)
CT Scan
Case Three
72 yo M farmer with PMHx of HTN, smoking, dyslipidemia
Presented with a three day history of right-sided weakness
Examination
Awake, alert
Normal language exam
Full visual fields
Mild right UMN facial weakness
Right pronator drift, decreased dexterity of right hand/fingers
Mild right leg weakness
Significant clumsiness of right arm and leg (finger-to-nose and heel-shin testing)
Imaging
MRI Scan
Case Four
73 yo M with PMHx of HTN, PVD, impaired fasting glucose, mild cognitive impairment
Presents with diplopia, dysarthria, and right-sided weakness
Examination
Awake, alert
Normal language exam, but dysarthric
Full visual fields
Left ptosis, mild anisocoria (OD<OS), eye deviated "down and out"
Right arm and leg weakness
Imaging
MRI Scan
Case Five
74 yo M with PMHx of HTN, smoking, A. Fib, surgical repair of spinal dural fistual (residual Rt LE weakness with upgoing toe)
Presents with 4 day history of nausea, vomiting, malaise
3 days ago - gait ataxia
On the day of presentation, ataxia worsening, fell at home, came to hospital
Denied headache, neck pain, or recent trauma
Examination
Awake, alert
Normal language
?mild diminished pinprick sensation on right side of face
left-beating horizontal nystagmus
decreased gag
right UE dysmetria on finger-to-nose testing
severe gait ataxia with right lateralpulsion
Imaging
MRI Scan
Case Six
77 yo M adm to hospital with mild right-sided weakness and global aphasia, treated with IV tPA
2 days after admission, he had a seizure and required intubation for decreased LOC
off sedation, he was confused, with severe right-sided hemiparesis
Examination
Confused, drowsy
Unable to assess language due to ETT but does not follow commands
No response to visual threat on right side
No movement of right arm and leg
Withdraws left arm and leg to pain
Imaging
CT Scan (done after clinical deterioration)
Case Seven
79 yo M found down by his son in the garage
Last seen well the night before
Had managed to shovel the sidewalk before he collapsed
Examination
Drowsy, obeys some commands, incomprehensible speech, withdraws to pain
Left sided facial droop, no movement of left side
Withdraws right arm and leg to pain
Imaging
CT Scan
References
references in bold are highly recommended
Marx, J. J., & Thömke, F. (2009). Classical crossed brain stem syndromes: myth or reality? Journal of Neurology, 256(6), 898–903. doi:10.1007/s00415-009-5037-2
Schmahmann, J. D. (2003). Vascular syndromes of the thalamus. Stroke; a journal of cerebral circulation, 34(9), 2264–2278. doi:10.1161/01.STR.0000087786.38997.9E
Blumenfeld, H. (2002). Neuroanatomy through Clinical Cases, 1–480.
Haines, D. E. (2008). Neuroanatomy. Lippincott Williams & Wilkins.