Brain stem and cranial nerves

What are the 4D’s of brainstem region dysfunction?

Dysphagia

Dysarthria

Diplopia

Dysmetria

What is the role of the cerebellum?

Coordinates complex somatic motor patterns

Adjusts output of other somatic motor centers in brain and spinal cord

What is the role of the pons (Mesencephalon)?

Relays sensory information to cerebellum and thalamus

Subconscious somatic and visceral motor centres

What is the role of the medulla oblongata?

Relays sensory information to the thalamus

Autonomic centres for regulation of visceral functions such as cardiovascular, respiratory and digestive activities

What is the role of the midbrain (Mesencephalon)?

Processing of visual and auditory data

Generation of reflexive somatic motor responses

Maintenance of consciousness

What makes up the diencephalon?

Thalamus

Hypothalamus

What is the role of the thalamus?

Relay and processing centres for sensory information

What is the role of the hypothalamus?

Centers controlling emotions, autonomic functions and hormone production

What is the role of the cerebrum?

Conscious thought processes, intellectual functions

Memory storage and processing

Conscious and subconscious, regulation of skeletal muscle contractions

What are the key structures of the midbrain?

•Cerebral peduncles

•The Tectum ; Superior

    and  inferior colliculi

•Substantia Nigra

•Contains the Red Nuclei

   and Cranial nerves 3 & 4

•Peduncles contain motor

    pathways

What tract emerges from the midbrain?

Tectospinal

What reflex is the superior colliculi involved in?

Visual reflex

What reflex is the inferior colliculi related to?

Auditory reflex

What are the signs of a superior colliculus deficit?

paralysis of upward gaze, fixed pupils, lack of head movements to threat response

What are the signs of a medial lemiscus deficit?

Numbness of face and body of opposite side

What are the signs of a reticular formation deficit?

Loss of consciousness

What are the signs of a substantia nigra deficit?

Parkinsons like features

What are the signs of an occularmotor nerve deficit?

Loss of eye movement control on the same side- cause diploplia

What are the signs of a trochlear nerve deficit?

Upward gaze eyes, diploplia, blurred vision

What are the signs of a motor deficit?

Contralateral weakness

What are the signs of a pons deficit?

• Disorder of consciousness

• Sleep wake cycle

• Contralateral sensory deficit

• Ataxia

• Dysarthria

• Abducens- eye movement deficits

• Facial- saliva management problems, facial drop

• Vestibularcochlear- hearing deficits, balance deficits

• Locked in syndrome

What are the signs of a medullar deficits?

• Cardiac Arrest

• Respiratory failure

• Ataxia

• Hemiparesis

• Hypoglossal (XII)-Dysphagia

• Glossopharyngeal- Dysphagia, Taste deficits

• Vagus (CN X)- lack of gag reflex, dysphagia

• Accessory (CN XI)- head control, shoulder movements

What is the role of the reticular formation?

•Receives afferents from spinothalamic tracts & medial lemniscus

•Connects via thalamus to other parts of CNS

•Origin of medial & lateral reticulospinal tracts

•Filters repetitive and familiar stimuli

•Maintains sleep-waking rhythms, consciousness, attention.

•Damage can lead to permanent unconsciousness

What lesion of the brainstem is related to a decerebrate rigidity?

Lesions in midbrain

What lesion of the brainstem is related to a decorticate rigidity?

Lesions superior to mid brain

What does brain herniation coning cause?

•Expanding Mass or Space Occupying lesion Usually Slower

•Cerebral Oedema due to damage

•Blocking of the ventricles

What cranial nerves are in the midbrain?

Optic (II), Occulomotor (III) and Trochlear (IV)

What cranial nerves are in the pons?

Trigeminal (V), Abducens (VI), facial (VII) and vestibulocochlear (VIII)

What cranial nerves are in the medulla?

Glosopharyngeal (IX), vagus (X), accessory (XI) and hypoglossal (XIII)

What cranial nerve is in the nasal cavity?

Olfactory (I)

How can you differentiate between bells palsy and stroke?

Patients will have a weak smile, but will be able to close their eye tightly and wrinkle their forehead symmetrically in bells palsy

How do you assess the olfactory nerve?

• Test perception and identification of non-irritant materials

• Avoid irritation e.g tobacco and soaps

• One nostril closed while other open

How do you assess the optic nerve?

• Visual acuity-Snellen chart. Test each eye separately

• VIsual fields- gross testing confrontation advance moving finger from periphery to fixation point. More accurate 5mm red pin “cone vision”- central. white rods

• Pupil sized and reaction- both pupils constrict when light shone. Reaction to accommodation and convergence in eye. lesion in optic nerve will abolish response in both eyes

How do you assess the oculomotor, trochlear and abducens nerve?

• Pupil size and reaction- shine torch in affected eye contralateral constricts (its III nerve intact). When light shone on normal eye it constricts but opposite eye does not react

• Ptosis

• Occulomotor testing: 6 different directions of gaze

• Diplopia- direction and max displacement. Determine outer image

• Conjugate movement- nystagmus

How do you assess the trochlear nerve?

• Superior eye movement

• Damage- double vision when looking down

How do you assess the trigeminal nerve?

• Pain over whole face

• Sensory pattern pain

• Corneal reflex- wisp of cotton

• Motor- wasting of temporalis muscle

• Jaw jerk

• Damage: weak jaw opening and facial sensory loss

How do you assess the Abducens nerve?

• Eye movement

• Damage- diplopia when looking to lesioned side

How do you assess the facial nerve?

• Observe in talking- looking for asymmetry

• Eye closure

• Mouth movement

• Wrinkle forehead

• Close eyes

• Purse lips

• Show teeth

• Damage: Bells Palsy

How do you assess the vestibulocochlear nerve?

• Hearing

• Vibration fork

• Damage: disturbance in balance and deafness

How do you assess the glossopharyngeal nerve?

• Considered with vagus

• Voice-ah

• gag reflex and swallowing-low tone in palatal region

How do you assess the vagus nerve?

• Parasympathetic component heart

• Damage dysphagia

How do you assess the accessory nerve?

• SCM and trapezius muscle

• Rotate head against resistance and shrug shoulders

How do you assess the hypoglossal nerve?

Stick tongue out- atrophy, fibrillation