Neurology: Cranial Nerve and Upper nerve disorders

Question 1

What are the clinical features of Cerebellopontine angle lesions?

Answer 1

• Features: Can compress the 5^th, 7^th and 8^th nerve
• Presentations:
  
  • Progressive deafness
  • Left facial numbness and weakness
  • Trigeminal neuralgia

Question 2

What is the facial nerve?

Answer 2

• Facial nerve is the main nerve supplying the structures of the second embryonic branchial arch.
• Predominantly an efferent nerve to the muscles of facial expression, digastric muscle and also many glandular structures. Few afferent fibres which originate in the cells of its genicular ganglion and concerned with taste.
• Supplies ‘face, ear, taste, tear’
  
  • Face: muscles of facial expression
  • Ear: nerve to stapedius
  • Taste: supplies anterior two-thirds of tongue
  • Glands: parasympathetic fibres to lacrimal glands, also salivary glands

Question 3

What is the path of the Facial Nerve?

Answer 3

• Subarachnoid path
  
  • Origin: motor- pons, sensory- nervus intermedius
  • Pass through the petrous temporal bone into the internal auditory meatus with the vestibulocochlear nerve. Here they combine to become the facial nerve.
• Facial canal path
  
  • The canal passes superior to the vestibule of the inner ear
  • At the medial aspect of the middle ear, it becomes wider and contains the geniculate ganglion. 3 branches:
    
    • Greater petrosal nerve
    • Nerve to stapedius
    • Chorda tympani
• Stylomastoid foramen
  
  • Passes through the stylomastoid foramen (tympanic cavity anterior and mastoid antrum posteriorly)
  • Posterior auricular nerve and branch to posterior belly of digastric and stylohyoid muscle

Question 4

What are causes of Bilateral Facial Nerve Palsy?

Answer 4

• Sarcoidosis
• Guillain-Barre syndrome
• Lyme disease
• Bilateral acoustic neuromas (as in neurofibromatosis type 2)
• Bell’s palsy is relatively common it accounts for up to 25% of cases of bilateral palsy, but this represents only 1% of total Bell’s palsy cases

Question 5

How do LMN and UMN lesions present differently?

Answer 5

• Upper motor neuron lesion ‘spares’ upper face i.e. forehead
• Lower motor neuron lesion affects all facial muscles

Question 6

What are causes of Unilateral Facial Nerve Palsy?

Answer 6

• Lower Motor Neuron
  
  • Bell’s palsy
  • Ramsay-Hunt syndrome (due to herpes zoster)
  • Acoustic neuroma
  • Parotid tumours
  • HIV
  • Multiple sclerosis (may also cause an UMN palsy)
  • Diabetes mellitus
• Upper motor neuron
  
  • Stroke

Question 7

What is Bell’s Palsy?

Answer 7

• Acute peripheral facial palsy that is unilateral. Exact cause is unknown and believed to be as a result of swelling and inflammation.
• Possibly a reaction that occurs after viral infection. Symptoms usually improve within few weeks with complete recovery in about six months

Question 8

What are symptoms of Bell’s Palsy?

Answer 8

• Rapid onset of mild to total paralysis on one side of the face occurring within hours to days
• Facial droop or difficult making facial expression such as closing your eye or smiling
• Drooling
• Pain around the jaw or in or behind your ear on the affected side
• Increased sensitivity to sound on affected side
• Headache
• Loss of taste
• Changes to amount of tear and saliva you produce

Question 9

What are causes of Bell’s Palsy?

Answer 9

• Cold sores and genital herpes
• Chicken pox and shingles
• Infectious mononucleosis
• Cytomegalovirus infections
• Respiratory illnesses
• German Measles
• Mumps
• Flu
• Hand-foot and mouth disease

Question 10

What are complications of Bell’s Palsy?

Answer 10

• Irreversible damage to facial nerve
• Abnormal regrowth of nerve fibres
• Partial or complete blindness of the eye that won’t close due to excessive dryness and scratching of the clear protective covering of the eye

Question 11

What is an essential tremor?

Answer 11

• Causes bilateral, fast, low-amplitude tremor mainly in the upper limbs. Tremor is postural such as when holding glass or cutlery. The tremor is slowly progressive
• Head and voice are occasionally involved.
• Anxiety can exacerbate the tremor
• Often inherited as autosomal dominant trait

Question 12

How is Essential Tremor Managed?

Answer 12

• Assure patient it’s not Parkinson’s disease which it can be confused with
• Small amounts of alcohol, beta-blocker, primidone or gabapentin may help
• Sympathomimetics can make all tremors worse
• Stereotactic thalamotomy and thalamic DBS are used in severe cases.

Question 13

What is Carpal Tunnel Syndrome?

Answer 13

• Median nerve entrapment at the wrist in the limited space of carpal tunnel
• Thickened ligaments tendon sheaths or bone enlargement can cause it but usually idiopathic.
• Has been linked to Hypothyroidism, Pregnancy, Rheumatoid disease, Acromegaly, and Amyloidosis

Question 14

What are symptoms and signs of Carpal Tunnel Syndrome?

Answer 14

Symptoms

• Patient wakes up with numbness, tingling and pain in median nerve distribution. Pain may radiate to the forearm
• Wasting of thenar eminence muscle develop with sensory loss in radial three and half fingers

Signs

• Tinel’s Sign: Pain produced by taping nerve in carpal tunnel
• Phalen’s Test: Pain produced by holding wrist in flexion

Question 15

What are management of Carpal Tunnel Syndrome?

Answer 15

• 1^st step: Splint to hold wrist in dorsiflexion overnight. Used nightly for several weeks and may produce full recovery
• 2^nd step: Corticosteroid injection into the carpal tunnel may then be trialled after
• Definitive: Surgical decompression
  
  • Persistent symptoms or nerve damage produce prolonged latency across carpal tunnel on nerve conduction studies

Question 16

What is the risk factors of degenerative cervical myelopathy?

Answer 16

• Smoking (affects intervertebral discs)
• Occupation with high axial loading
• Genetics

Question 17

How does degenerative cervical myelopathy present?

Answer 17

• Very variable day to day, difficult to detect early, but worsening signs/deterioration should be warning signs
• Bilateral median nerve dysfunction is very suggestive of a diagnosis of degenerative cervical myelopathy (DCM) rather than bilateral carpal tunnel syndrome
• Usually older persons with limb neurology, twitches/fibrillations

Question 18

What is the investigations of degenerative cervical myelopathy?

Answer 18

• MRI of the cervical spine is gold standard – disc generation among other signs

Question 19

What is the management of degenerative cervical myelopathy?

Answer 19

• Refer to specialist spine services (neurosurgery or orthopaedic spinal surgery) – for decompression surgery
• Early treatment is crucial as any existing cord damage can be permanent
• Close observation is an option for mild stable disease
• Physiotherapy should only be initiated by specialist services as manipulation can cause more spinal cord damage

Question 20

What are symptoms and signs of Ulnar Nerve Palsy?

Answer 20

Compression of nerve in cubital tunnel at the elbow. This can follow prolonged or recurrent pressure and elbow fracture. Symptoms and signs are:

• Clawing of the hand
• Wasting of interossei and hypothenar muscle
• Weakness of interossei and medial two lumbricals
• Sensory loss in little finger and splitting of the ring finger.

Question 21

What is Horner’s Syndrome?

Answer 21

• Sympathetic nerve supply to eye is 3-neurone pathway originating in the hypothalamus and descending by way of brainstem and cervical cord to T1 nerve root, paravertebral sympathetic chain and on via carotid artery wall to the eye.
• Damage to any part of the pathway result in Horner syndrome.
• Significant not only because of effect of vision and also indicates underlying pathology

Question 22

What are causes of Horner’s Syndrome?

Answer 22

• Massive cerebral infarction
• Brainstem demyelination or lateral medullary infarction
• Syringomyelia and Cord Tumours
• Apical lung tumour or tuberculosis
• Cervical Rib (thoracic outlet syndrome)
• Brachial plexus trauma
• Following thyroid/laryngel/carotid surgery
• Carotid artery dissection
• Neoplastic infiltration
• Cervical sympathectomy
• Wallenberg’s syndrome
• (Transient) Horner’s syndrome

Question 23

What are signs of Horner’s Syndrome?

Answer 23

• Unilateral miosis
• Partial ptosis
• Loss of sweating on same side
• Possible subtle conjunctival injection and enophthalmos

Question 24

What is the definition of Radiculopathies?

Answer 24

• Conduction block in axons of spinal nerve or its roots with impact on motor axons causing weakness and on sensory axons causing anaesthesia and/or anaesthesia
• Radiculopathy is a state of neurological loss and may or may not be associated with radicular pain. Radicular pain is pain deriving from damage or irritation of spinal nerve tissues particularly dorsal root ganglion

Question 25

What are causes of Radiculopathy?

Answer 25

• Intervertebral disc prolapse – lumbar spine predominantly affected by repeated minor stresses that predispose to rupture of annulus fibrosus and sequestration of disc material
• Degenerative disease of the spine – leading to neuroforaminal or spinal canal stenosis. Most mobile segment of spine and degenerative change is normal part of ageing process; 80% of population over 55 years old have degenerative changes between C55/6 and C6/7
• Fracture – either trauma or pathological
• Malignancy – most commonly metastatic
• Infection – such as extradural abscess, osteomyelitis or herpes zoster

Question 27

What are symptoms/signs of Radiculopathies?

Answer 27

• Sensory features – paraesthesia and numbness
• Motor features – weakness
• Radicular pain typically burning, deep, strap-like or narrow pain. Not uncommon for radicular pain to be intermittent

Question 28

What are examinations of Radiculopathies?

Answer 28

• Examine for dermatomal and myotomal involvement to evaluate cauda equina syndrome by assessing pinprick sensation in perianal dermatomes, anocutaneous reflex, anal tone and rectal pressure sensation

Question 29

What are red flag symptoms of Radiculopathies?

Answer 29

• Cauda Equina Syndrome: faecal incontinence, urinary retention, saddle anaesthesia
• Infection: Immunosuppression, Intravenous drug use, Unexplained fever
• Chronic Steroid Use: Fracture or Infection
• Fracture: Significant Trauma, Osteoporosis or metabolic bone disease
• Malignancy: New onset after 50 years old
• Metastatic disease: History of malignancy

Question 30

What are differentials of Radiculopathies?

Answer 30

• Referred pain
• Myofascial pain
• Thoracic outlet syndrome
• Greater Trochanteric Bursitis
• Iliotibial band syndrome
• Meralgia Paraesthetica
• Piriformis syndrome

Question 31

What is the management for Radiculopathies?

Answer 31

• Definitive long-term management depends on underlying cause.
  
  • Only condition requiring emergency surgical treatment is Cauda Equina Syndrome
  • IV disc prolapse non-operatively managed but indication for surgical treatment include unremitting pain despite comprehensive non-surgical management, progressive weakness and new or progressive myelopathy
• Symptomatic Management
  
  • Analgesia: WHO analgesic ladder however neuropathic pain medication frequently utilised
    
    • Amitriptyline usually 1^st-line
      
      • Alternatively, pregabalin and gabapentin
    • Muscle spasms can be managed with benzodiazepines
  • Physiotherapy remains important part of management in patient group

Question 32

What is the management of an Ulnar Nerve palsy?

Answer 32

Decompression and transposition of the nerve at the elbow is sometimes helpful but often disappointing.