GS - Brainstem Case Studies Flashcards
What 3 questions should you ask yourself why diagnosing a neurological lesion?
1). Where is the lesion located?
- Localising symptoms or signs present ?
- Function anatomy, including blood supply
2). What type of lesion?
- Speed of onset of symptoms
- The natural history of the lesion (disease process); Progressive, regressive, remitting-relapsing
- A lesion restricted to the nervous system/part of a systemic illness (more than one system involved)
3). What is the treatment ?
What things should you think about when trying to work out the type of lesion n the brainstem?
Vascular - older, male, sudden onset (minutes), vascular risk factors present
Infectious - onset of symptoms could be acute (hours) or subacute (days). Systemic inflammatory features present (e.g fever)
Autoimmune - Young, female. Possibly relapsing - remitting course (e.g multiple sclerosis), maybe part of a systemic illness (vasculitis)
Tumour - Slow growing, gradual, weeks-years. Primary or metastasis
Degenerative - Slow, months to years, e.g Parkinson’s disease, motor neurone disease
(Ones closer to top faster onset, ones at bottom slower onset)
What are the medial tracts?
- Corticospinal tract (motor opposite side body)
- Medial lemniscus (ML) of dorsal column pathway (senses opposite side of body)
- Medial longitudinal fasiculus (connects eye nuclei III + VI)
How can you remember what 4 structures and in the midline?
4 “M” structures in midline
Dorsal
Motor nuclei and nerve (ipsilateral features of CN lesion in the head and neck)
Medial longitudinal fasiculus (ipsilateral inter-nuclear opthalamoplegia)
Medial lemniscus (contralateral loss of joint position sense)
Motor pathway (corticospinal and corticobulbar) - (contralateral UMN signs in limbs and trunks)
Vental
What are signs of UMN lesion?
UMN signs;
- Spastic paresis/paralysis
- Spasticity (tone)
- Hyper-reflexia
- Clonus sustained rhythmic contractions)
- Positive Babinski’s (up-going plantar reflex)
What are the lateral tracts ?
- Spinothalamic/anterolateral (crossed body, pain/temp defect)
- Spinocerebellar (ipsilateral body, ataxia)
- Sympathetic (ipsilateral from hypothalamus to spinal cord to eye; corners)
(also nucelus ambiguus but it doesn’t follow the rule that all motor is medial!)
How can you remember what 4 structures lie to the side?
4 “S” structures on the side (we can add SVE nuclei to this list!)
Dorsal
Spinocerbellar pathways (Ipsilateral ataxia in the limbs)
Spinothalamic pathway (contralateral loss of pain and temperature in the limbs)
Sensory nucleus of CN V (ipsilateral loss of fine touch, pain and temperature in face and anterior 2/3 of scalp)
Sympathetic pathway (ipsilateral Horner’s syndrome: partial ptosis, mitosis)
Ventral
What is the blood supply of the cerebellum?
The cerebellum receives vascular supply from three main arteries that originate from the vertebrobasilar anterior system: the superior cerebellar artery (SCA), the anterior inferior cerebellar artery (AICA), and the posterior inferior cerebellar artery (PICA).
How do vessels generally supply the medulla?
Ventral arteries - ventral and central
Wrapping arteries - lateral and dorsal
What is the blood supply of the Medulla ?
Image
What is the blood supply of the Pons ?
Image
What is the blood supply of the Midbrain ?
Starts to rotate where leg and arm are n different locations and will join together soon
This is more specialist stuff, just appreciate rotation
What is the blood supply of the brainstem from the Paramedian Arteries?
Structures in the medial aspect of the brainstem including CN and their nuclei likely to be effected any a vascular lesion at different levels within the brainstem
Para”M”median arteries;
Midbrain (CN III, IV) - Posterior cerebral artery
Pons (CN VI) - Basilar Artery
Medulla (CN XII) - Anterior spinal artery
Motor nuclei and nerve
Medial longitudinal fasciculus
Medial lemniscus
Motor pathway (corticospinal and corticobulbar)
What is the blood supply of the brainstem from the long Circumferential arteries ?
Structures on the sides of the brainstem including CN and their nuclei likely to be effected by a vascular lesion at the different levels within the brainstem
“C” (“S”) The Long Circumferential arteries;
Midbrain - (CN V - Sensory nuclei) - Posterior cerebral artery and superior cerebellar artery
Pons (CN V, VII, VIII) - (pontine) branches of the basilar artery
Medulla (CN V, IX, X) - PICA (also vertebral)
(Lateral medullary syndrome might be due to PICA)
Spinocerebellar pathways
Spinothalamic pathways
Sensory nucelus of CN V (3 parts)
Sympathetic pathway
What are the main principles of diagnosing brainstem lesions?
- If motor tract involved - contralateral hemiparesis (UMN signs)
- If ascending tracts (sensory) involved - contralateral loss of fine touch and JPS or loss of pain and temperature in arms and legs
- Ipsilateral ataxia in the limbs (co-ordinaton balance and speech)
- Ipsilateral cranial nerve signs (LMN) in the head and neck
- Ipsilateral Horner’s syndrome
- Other non-cranial nerve nuclei may be involved if lesion within BS (rather than external compression)
How can you locate brainstem lesions?
Locating brainstem lesions;
- Identify potential cranial nerve/nucleus generating symptom/sign (already suggest level, side and position)
- Identify any tract symptoms and signs in head and/or body crossed or uncrossed)
Combine information to decide on a level, side, position (medial/lateral). Use rule(s) of 4 as aide memoire.
Midbrain, Pons, Medulla
Right/left
Medal/lateral
A 45 year old male presents with a sudden onset of dysarthria. On examination he is found to have a left hemiplegia; deviation of his tongue to right and loss of JPS to the upper and lower left limbs
What is wrong with him?
Right hypoglossal nucelus (medulla) tongue deviates to affected side. Dorsal column (medial lemniscus) and corticospinal effects (both crossed to left body. All medial structures.
Therefore medial medullary syndrome with sudden onset vascular cause - anterior spinal artery stroke
What are some non-cranial nerve centres and structures in brainstem to consider with brainstem lesions?
Midbrain;
Medial geniculate - Relay auditory stimuli to cerebral cortex
Red nucleus - Motor - co-ordnation (part of extra pyramidal system)
Substantia nigra - Motor co-ordination (part of extra pyramidal system)
Superior colliculus - Co-ordinates eye movement in response to visual & other stimuli
Inferior colliculus - Co-ordinates head & upper body movement in response to auditory stimuli
Reticular formation (RetF) - Consciousness & cortical arousal
Pons;
- Pontine nuclei - link between cerebral cortex and cerebellum
- Reticular formation - consciousness & cortical arousal
Medulla;
- Olive - auditory control (superior olive) & movement control (inferior olive)
- Vital centres - Regulate heart rate; breathing; blood vessel diameter
- Non vital centres - co-ordinate swallowing, vomiting, cough; sneezing, hiccupping
- Reticular formation - conscious & cortical arousal
A 35 year old female presents with tinnitus and gradual loss of hearing in the right ear. The patient mentions she has also been having symptoms of vertigo over the past few weeks with occasional vomiting, in addition too slight weakness on the right side of her face. On examination sh is found to have mild nystagmus, a right-sided facial paraesthesia and loss of corneal reflex
What does she have?
1). The lesion is lateral in SVE and somatic sensory nuclei at the level of pons: Tinnitus and sensorineural hearing loss in right ear and vertigo so right vestibulocochlear nerve/nucelus
2). Right facial weakness and paraesthesia so facial nerve/nuclei and trigeminal nerve/nuclei on the right. Loss of corneal reflex is an early sign along with wellness of muscles of mastication.
Right cerebellum maybe involved so nystagmus (ataxia, intention tremor (arm) are also possible).
Most likely an acoustic neuroma/vestibular schwannoma (benign tumour) growing gradually (slow onset) in the cerebellar-pontine angle cistern (long tracts to the side are often deeper to the lesion and unaffected).
Cerebellar-pontine angle cistern;
- CSF filled subarachnoid space within posterior cranial fossa in between anterior surface of cerebellum, lateral surface of pons and petrous part of temporal bone
- CN V, VI, VII and IX are in close proximity and maybe compressed as the tumour grows.
A 40 year old female is undergoing a yearly physical exam at her GP. Upon examination of her visual system, she is found to have impaired adduction in the let eye when asked to look to the right. There is also an apparent nystagmus in the right abducting eye. She is also found to have impaired adduction of the right eye when asked to look left. There is also an apparent nystagmus in the left abducting eye. On further questioning she tells her GP she had an episode of pain behind the right eye with partial loss of colour vision, which lasted 1 month in her 30’s
What is wrong with this patient?
Recognisable clinical pattern - Internuclear ophthalmoplegia due to lesion in MLF
Adduction defect combined with contralateral nystagmus - adduction defects same side as MLF lesion
Medial Longitudinal Fasciculus is on of the first central tracts to be myelinated during development (oligodendroglia)
Demyelinating conditions - e.g multiple sclerosis can slow conduction through MLF causing inter-nuclear ophthalmoplegia (commonly bilateral lesions)
