General
- Syndromes rarely occur in textbook form. A flexible mind is needed to correctly analyze and interpret the constellation of signs and symptoms with which patients, in the real world, present.
Location | Ventral | Central | Dorsal |
Midbrain | Weber | Benedikt Claude | Parinauds |
Location | Lateral | Medial | |
Pons | Brissaud-Sicard (Anterior/lateral) Marie-Foix syndrome (lateral/inferior) Locked in (Bilateral anterior) | Millard-Gubler | Foville's Babinski-Nageotte syndrome (Inferior medial pons) |
Medulla | Babinski-Nageotte syndrome (Hemi medulla = Wallenberg + Dejerine) | Wallenberg | Dejerine |
Rules to identify location of lesion
- Using the following we can identify the location of lesion
- Functionally distinct ascending and descending tracts are spread along the transverse axis
- Functionally distinct cranial nerve the lesion.
- What level? Three groups of cranial nerve nuclei aid in localising the level of a brainstem lesion:
- Oculomotor and trochlear nuclei
- Which produce diplopia and ipsilateral pupillary disturbances with ptosis (oculomotor nerve)
- Located at the level of the midbrain.
- Abducens nucleus and the facial nucleus
- Which produce diplopia (abducens nerve) and ipsilateral facial weakness (facial nerve)
- Located at the level of the pons .
- Nucleus ambiguus (IX, X, and XI), the dorsal motor nucleus of the vagus, and the hypoglossal nucleus
- Speech and swallowing,
- Located at the level of the medulla
- Medial or lateral? Localising long tracts include the following:
- The corticospinal tract and the medial leminiscus
- Which produce
- Hemiplegia (corticospinal tract) and
- Loss of vibratory and position sensation (medial leminiscus) on the side opposite the lesion,
- Located medial in the brainstem.
- The lateral spinothalamic tract and the descending sympathetic fibers
- Which produce
- Contralateral loss of pain and temperature sensation (spinothalamic tract) and
- An ipsilateral Horner syndrome (descending sympathetic fibers)
- Located lateral in the brainstem.
- The sine qua non of a lesion in the brainstem is thus the “crossed motor/sensory syndrome”: motor/sensory loss affecting one side of the face and the opposite side of the body.
- This results because cranial nerve nuclei and long ascending and descending tracts produce ipsilateral and contralateral signs, respectively.
- Two questions should arise regarding the patient with a crossed motor/sensory syndrome:
- What cranial nerves are involved?
- Tells you which level is lesion
- What long tracts are involved?
- Tells you whether it is medial or lateral
- Finally, in the clinical context of a vascular lesion (i.e., abrupt onset), the distribution of the lesion should be compared with the brainstem blood supply to determine which vessel has been occluded.
Summary
Vascular territory | Anatomical location | Stroke syndrome | Clinical findings |
Unilateral PCA | Occipital lobe | Contralateral homonymous hemianopsia | Homonymous hemianopsia with mascular sparing |
ㅤ | Dominant occipital lobe plus splenium of corpus callosum | Alexia without agraphia | Homonymous hemianopsia and alexia without agraphia |
ㅤ | Ventral occipital cortex; infracalcarine | Achromatopsia | Loss of color differentiation contralateral to the side of the lesion, can be associated with a quadrantanopsia |
ㅤ | Optic radiation OR supracalcarine | Inferior quadrantanopsia | Inferior quadrantanopsia |
ㅤ | Myers loop (temporal lobe) or infracalcarine | Superior quadrantanopsia | Superior quadrantanopsia |
Bilateral PCA | Both occipital lobes | Cortical blindness | Bilateral cortical blindness with normal ophthalmological findings |
ㅤ | ㅤ | Cortical blindness with denial of blindness and confabulations or visual hallucinations |
Brainstem nuclei injury and its associated clinical features
Structure | Main ocular motor function | Clinical findings in lesions |
Abducens nucleus* | Conjugate horizontal gaze | Ipsilateral conjugate horizontal gaze palsy |
PPRF: paramedian pontine reticular formation | Horizontal saccade generation | Selective horizontal saccadic palsy with sparing of vergence and pursuit |
MLF: Medial longitudinal fasciculus | Conjugate gaze and VOR (vestibuloocular reflex) | Internuclear ophthalmoplegia (INO); Convergence can be spared; Skew deviation or ocular tilt reaction (OTR); Asymmetric vertical VOR better with upward slow phases; Dissociated vertical-torsional nystagmus |
CTT: central tegmental tract | Conveys information from cerebellum to inferior olive | Oculopalatal tremor |
Vestibular nucleus (rostral) | VOR | Spontaneous nystagmus; Abnormal head impulse sign; Skew deviation |
Midbrain syndromes
Ventral Midbrain Syndrome (Weber's Syndrome)
- Lesion of the cerebral peduncle affects
- Cortico-spinal tract
- Contralateral hemiplegia
- Oculomotor nerve fascicle
- Diplopia
- Down and out
- Pupillary dilatation (mydriasis)
- Ptosis
Central (Tegmental) Midbrain Syndrome (Benedikt's Syndrome)
- A lesion of the tegmentum of the midbrain affects
- Oculomotor nerve
- Diplopia
- Down and out
- Ptosis
- Mydriasis
- Red nucleus
- Contralateral limb tremor/involuntary movements
- Medial lemniscus.
- Contralateral propioception and vibratory sensation loss
Dorsal Midbrain Syndrome (Parinaud's Syndrome)
- A lesion (tumor in the pineal region or hydrocephalus) results in compression of the superior colliculi and tectum (Pretectal area)
- Causing isolated causes
- Near-light dissociation: pupil to respond accommodation but there is no pupillary response to light
- Damage to posterior commissure
- Up gaze palsy (sunsetting eyes)
- Damage to posterior commissure
- Retraction convergence nystagmoid
- Damage of the midbrain supranuclear fibers.
- These fibers normally exert an inhibitory effect on the third nerve nucleus
- Collier's sign: lid retraction
- Damage of the midbrain supranuclear fibers.
- These fibers normally exert an inhibitory effect on the third nerve nucleus
Pons syndromes
Lateral Pontine Syndrome (Millard-Gubler Syndrome)
- Occlusion of
- Anteroinferior cerebellar artery caudally OR/AND
- Superior cerebellar artery rostrally.
- Signs and symptoms:
- Ipsilateral impairment of facial pain and temperature sensation
- Spinal tract and nucleus of the trigeminal nerve
- Contralateral impairment of body pain and temperature sensation
- Spinothalamic tract (crosses as the level it enters the cord)
- Ipsilateral Horner syndrome
- Descending sympathetic fibers
- Nausea, vomiting, vertigo, and nystagmus
- Vestibular nuclei and connections
- Deafness and tinnitus
- Cochlear nerve or nucleus
- Ipsilateral limb and gait ataxia
- Inferior cerebellar peduncle
- Ipsilateral facial paralysis
- Facial nerve
- Paralysis of gaze to the side of the lesion
- Paramedian pontine reticular formation
- Connection: Cortex → PPRF → CN6 → MLF → CN3
- A medial structure: but it is involved probably because the centre of brainstem has poorer blood supply.
- Lesion in pons and not midbrain (midbrain lesion causes vertical gaze palsy)
Medial Pontine Syndrome (inferior medial pontine=Foville's)
- Occlusion of paramedian branches of the basilar artery.
- Signs and symptoms:
- Contralateral hemiparesis
- Corticospinal tract (85% crosses at caudal medulla; 15% at spinal cord)
- Contralateral loss of vibratory and position sense
- Medial lemniscus (crosses at caudal medulla at formation of cuneatus and gracilis nucleus)
- Ipsilateral limb and gait ataxia
- Cerebellar connections (middle cerebral peduncle?)
- Paralysis of the ipsilateral lateral rectus muscle
- Abducens nerve
- One and a half syndrome
- Internuclear ophthalmoplegia (contralateral-gaze defect to the side of lesion on the contralateral eye)
- Medial longitudinal fasciculus
- Crosses at the CN6 nuclei level
- Paralysis of gaze to the side of the lesion on both eyes (ipsilateral)
- Paramedian pontine reticular formation
- Bilateral ventral pontine lesions (secondary to thrombosis of the basilar artery) result in the dramatic “locked-in syndrome.”
- The patient remains alert but is rendered immobile
- Quadriplegia
- Corticospinal tract
- Complete aphonia
- Corticopontine tract
- Sparing of the oculomotor system
- Can move eye in all direction but has horizontal gaze palsy
- Only vertical gaze is intact as it is control in the midbrain
- Noncommunicative.
Brissaud-Sicard syndrome
- Due to
- Antero-lateral and inferior pons stroke.
- Brainstem gliomas
- Clinical features
- Ipsilateral CN VII hemispasm
- Damage to the CN VII nucleus or nerve root
- Contralateral hemiparesis
- Damage to the corticospinal tract
Medulla syndromes
Lateral Medullary Syndrome (Wallenberg Syndrome)
- Occlusion of
- Vertebral artery (80%)
- PICA
- Infarction of lateral medulla
- Signs and symptoms:
- Ipsilateral impairment of facial pain and temperature sensation
- Spinal tract nucleus of the trigeminal nerve
- Contralateral impairment of body pain and temperature sensation
- Spinothalamic tract (crosses at the level it enter spinal cord)
- Ipsilateral limb and gait ataxia
- Cerebellar connections
- Ipsilateral Horner syndrome:
- ptosis, miosis, anhydrosis
- Descending sympathetic fibers
- Nausea, vomiting, vertigo, and nystagmus
- Vestibular nuclei and connections
- Dysphagia and dysarthria
- Nucleus ambiguus: CN9, 10
- This is essentially the only location where a lesion will produce sensory loss on one side of the face (ipsilateral to the lesion) and contralateral sensory loss in the body
- Patient can develop severe cerebellar swelling that responds to neurosurgical decompression (the tissue aspirates easily).
- Need to rule out vertebral dissection as a cause which can be treatment with heparin
- Prognosis (out of 43 pts):
- 12% patients died during the acute phase from respiratory and cardiovascular complications
- 2 new posterior-fossa strokes occurred.
- Recurrent vertebrobasilar territory stroke rate was 1.9% per year.
Medial Medullary Syndrome (Dejerine's Syndrome)
- Medial medulla
- Contains the M
- (Motor) corticospinal tract
- Medial lemniscus
- (Motor) Hypoglossal nucleus
- Supplied by
- Vertebral artery or
- Anterior spinal artery
- Signs and symptoms:
- Contralateral hemiparesis
- Corticospinal tract (crosses at caudal medulla 85%; crosses at the level it enters 15%)
- Contralateral loss of vibratory and position sense
- Medial lemniscus (Crosses after it exits the cuneatus and gracilis nucleus)-caudal medulla
- Ipsilateral paralysis of the tongue
- Tongue deviates to side of lesion due to involvement of the hypoglossal nucleus
- Bilateral lesions of the medial medulla result in
- Quadriplegia (with facial sparing),
- Facial motor nuclei in pons
- Bilateral corticospinal tract
- Complete paralysis of the tongue,
- Bilateral Hypoglossal motor nuclei
- Complete loss of vibratory and position sensation below the head.
- Bilateral medial leminiscus
- Trigeminal sensory nucleus located in more cranially in midbrain, pons and cranial medulla not affected
- Note that the dorsolateral spinothalamic tract is not affected.
- Therefore, pain and temperature sensation is spared.
Basilar artery associated deficits
Location | Supply | Syndrome | Symptoms/signs |
Top of the BA | Midbrain, thalamus, and mesial temporal lobes and occipital lobes | Top of the basilar | Somnolence, peduncular hallucinosis, convergence nystagmus, skew deviation, oscillatory eye movements, Collier's sign (retraction and elevation of eyelids), vertical gaze paralysis |
Mid-BA | Lateral and medial pons | Lateral mid-pontine syndrome | Ipsilateral loss of facial sensation and motor function of the trigeminal nerve, ipsilateral dysmetria |
ㅤ | ㅤ | Medial mid-pontine syndrome | Ipsilateral dysmetria, contralateral arm and leg weakness and gaze deviation |
Pontine paramedian perforators | Anteromedial pons | Dorsal mid-pontine syndrome | Ipsilateral nuclear facial palsy, horizontal gaze palsy, and contralateral arm and leg weakness |
Short pontine circumferential arteries | Anterolateral pons | Superior medial pontine syndrome | Ipsilateral intranuclear ophthalmoplegia, palatal, facial, pharyngeal and/or ocular myoclonus, dysmetria, contralateral arm and leg weakness, ocular bobbing |
Proximal BA | Lower pons | Locked-in syndrome | Quadriplegia, horizontal gaze paralysis, bifacial, paralysis, and tongue and mandibular weakness |
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