Clinical Neurology

Embryologic development of the nervous system

Blastocyst = 128 cells

Then begin to layer:

Ectodermal - skin, nervous system

Mesodermal - connective, muscle, bones, fat

Endodermal - glands

Carcinoma vs. Sarcoma

From ecto/endodermal layers: carcinoma

From mesodermal layer: sarcoma

Neural Tube:

Posterior Neuropore –

· closes to become spinal cord by 28^th day of gestation

· Defects: spinabifida syndromes

Anterior Neuropore –

· closes to become brain by 24^th day of gestation

· Defects: anencephaly, encephalocele

Essential to closure of neural tube: FOLIC ACID

Other risk factors of defects:

· hyperglycemia

· hyperthermia

· genetics

· drugs

· obese mothers

· fetal alcohol syndrome

Spina bifida occulta = “tether spinal cord syndrome”

Neurofibromatosis (Von Recklinghausen’s disease)

Neurotrophic viruses: the herpes family

HSV Type I - dorsal root of trigeminal nerve

HSV Type II - sacral nerve

Dermatomes

Reflexes

S1-S2 Achilles

L3-L4 Knee (patellar)

C5-C6 Biceps, brachioradialus

C7-C8 Triceps

Embryologic development of diaphragm

Hair pattern

Developmental deficits

Cerebral Cortex

Frontal lobe:

· inhibitory

· judgment and insight

· moods/emotion/affect

· socialization (socialized behavior)

· primitive reflexes (become repressed as we grow up)

· Broca’s area (voluntary expression)

· Pre-central gyrus (motor cortex)

Contains UMNs (upper motor neurons)

Lower motor neurons (in brainstem and spinal cord)

Sample reflex patterns

Temporal Lobe

· Wernicke’s area (receptive aphasia)

· Uncus (integration and discrimination between smells and sounds)

· Limbic system

· ANS (autonomic nervous system)

· Hippocampus (recent memory)

Parietal Lobe

· Post-central gyrus (integrates and discriminates tactile sensory information from the opposite site of the body)

Tests:

· graphesthesia

· stereognosis

· 2-point discrimination

· abstraction

· calculation

Occipital Lobe (integrates and discriminates visual sensory information)

Basal Ganglia:

Paired nuclei:

· caudates (produce dopamine) ---> Huntington’s chorea

· lenticular nucleus

· substantia nigra ---> Parkinson’s disease

· subthalamic nuclei

Cerebellum

· coordination

· synergy (smooth movement)

· equilibrium

· muscle tone

· skill memory

Tests:

· finger-to-nose

· rapid alternating movements

· reach for object

· Romberg test

Brainstem

Check function with cranial nerves

Midbrain (CN III, IV)

CN III (oculomotor)

CN IV (trochlear)

Pons (CN V, VI, VII, VIII)

CN V (trigeminal)

CN VI (abducens)

CN VII (facial)

CN VIII (acoustic)

Medulla (CN IX, X, XI, XII)

CN IX (glossopharyngeal)

CN X (vagus)

CN XI (spinal accessory)

CN XII (hypoglossal)

Prototypical health problems:

Bell’s palsy (facial nerve paralysis)

· Sx: preceding retroauricular headache, numbness of middle and lower areas of the face, otalgia, hyperacusis, decreased tearing, altered taste, and facial weakness with equal weakness in all branches of the seventh cranial nerve

· onset is rapid

· Possible causes: Lyme disease, Mycoplasma, sarcoid, vasculitis, diabetes, rickettsial disease, intracranial pathologic condition.

· Over 85% of cases will resolve without treatment within 3 weeks

· Use of steroids is controversial

Carpal tunnel syndrome

· Sx: pain, paresthesia, numbness, or a pins-and-needles sensation in the median nerve distribution of the hand, usually in the thumb, index and middle fingers, and radial aspect of the ring finger; nocturnal paresthesia is characteristic

· Sx. are a result of median nerve dysfunction because of increased pressure within the carpal tunnel

· Causes

· Exam: Tinel’s sign, Phalen’s sign

Headache

Primary headaches:

Migraine without aura (common migraine)

Must have at least 5 attacks that meet the following criteria:

· Headache attacks last 4-72 hours

· Headache has at least 2 of the following:

· unilateral location

· pulsating quality

· moderate or severe intensity (inhibits daily activity)

· aggravation by routine physical activity

During the headache, at least 1 of the following:

o nausea or vomiting

o photophobia and phosphoric

o No organic cause found by history, PE, neurologic exam

Migraine with aura (classical migraine)

Must have at least 2 attacks fulfilling the following criteria:

. At least 3 of the following are present:

· one or more fully reversible aura symptoms indicating focal cerebral cortical or brainstem dysfunction

· at least one aura symptoms develops gradually over more than 4 minutes

· no aura symptom last more than 60 minutes (duration proportionally increases if >1 aura symptom present).

· HA follows aura with free interval of less than 60 minutes (may begin before or with the aura). HA usually lasts 4-72 hours but may be absent.

. No organic cause found by history, PE, neurologic exam

Tension type headache

. Headache with at least 2 of the following:

· pressing or tightening quality

· mild or moderate intensity

· bilateral location

· no aggravation by routine physical activity

. No organic cause found by history, PE, neurologic exam

. Tension headache is separated into two subtypes based on frequency:

a. Episodic

- headache lasting 30 minutes to 7 days

- no N or V with headache

- photophobia and phonophobia are absent, or one but not the other is present

- at least 10 previous headaches as above, with number of headache days < 180/year and <15/month

b. Chronic

- headache average 15 days/month (180 days/year)

- no vomiting

- no more than 1 of the following: nausea, photophobia, or phonophobia

Cluster headache (episodic or chronic)

· Severe unilateral orbital, supraorbital, or temporal pain last 15-180 minutes untreated.

· Headache is associated with at least 1 of the following on the pain side:

· conjunctival injection

· lacrimation

· nasal congestion

· forehead and facial sweating

· rhinorrhea

· miosis

· ptosis

· eyelid edema

· Frequency of attacks ranges from 1-8 daily

· At least 5 attacks occur as above

Chronic paroxysmal hemicrania

. Severe unilateral orbital, supraorbital, or temporal pain always on the same side, lasting 2-45 minutes

. Attack frequency >5 a day for more than half the time (periods of lower frequency may occur)

. Headache is associated with at least 1 of the following on the pain side:

· conjunctival injection

· lacrimation

· nasal congestion

· rhinorrhea

· eyelid edema

· ptosis

. Absolute effectiveness of indomethacin (150 mg/day or less)

. At least 50 attacks occur as above.

. No organic cause found by history, PE, neuro exam

Secondary headaches

Increased intracranial pressure (pseudotumor cerebri)

· idiopathic, 19 of 100,000 in obese young females

· associated with tetracycline use

Tumor

· HA most common only complaint, though only 50% of tumors present with HA

· 17% have “typical” tumor HA (worse in morning, N, V, worse bending over)

Arteritis (giant cell, temporal)

· Most common symptom: nonspecific HA often with scalp or temporal artery tenderness

Acute effects of substance use/Substance withdrawal

Meningitis and herpes encephalitis

Drug-rebound headache (ergotamine induced, analgesic abuse, diazepam)

Carbon monoxide poisoning

Subarachnoid hemorrhage (SAH)

· generally have acute onset of worst headache of life

NOTE: Also remember simple causes such as sinusitis, toothache, temporomandibular joint (TMJ) syndrome.

Low back pain

· Mechanical causes account for up to 98% of cases of back pain. These include:

. disk injury

. degenerative changes in facet joints

. spondylosis (degenerative changes in vertebral bodies and disks that may result in nerve root impingement)

. spondylolisthesis (caused when a vertebra slides forward in relation to the vertebra below, commonly occurring at L5-S1)

. spondylolysis (a structural defect of the spine involving the lamina or neural arch of the vertebra)

. vertebral body fracture

. spinal cord stenosis

. myofascial or soft-tissue injury or disorder

. arachnoiditis and postoperative scarring

· Systemic disorders include primary tumors and metastatic tumors, infection, metabolic bone disease, vascular disorders

· Neurologic causes include myelopathy, lumbosacral plexopathy, neuropathy, myopathy

· Referred pain to back may come from GI disorders (pancreatitis, perforated ulcer), GU disorders (nephrolithiasis, prostatitis, pyelonephritis), GYN disorders (ectopic pregnancy, pelvic tumors), abdominal aortic aneurysm, or hip disorder

Parkinson disease:

· a slowly progressive movement disorder of unknown cause that primarily affects the pigmented, dopamine-containing neurons of the pars compacta of the substantia nigra.

· Cardinal symptoms: gross resting tremor (often pill-rolling involving mainly the hands and feet), bradykinesia, and muscular rigidity (described as lead pipe and cogwheel)

· Other features include masked face, decreased blinking, stooped posture, festinating gait (rapid populsion forward with inability to stop), increased sweating and salivation.

Tremor

Parkinsonian tremor:

· an asymmetric, regular, rhythmic, low-amplitude tremor, with slowly alternating flexion-extension contraction (4-8 cycles per second).

· Later the tremor becomes symmetric at 7-12 cycles per second.

· It is a tremor at rest, disappearing briefly during the course of a voluntary movement and reappearing when the limb is held in a stationary position.

Note: Different from essential tremor, a benign tremor, usually of the head, chin, outstretched hands, and occasionally the voice, usually made worse by anxiety or action.

· fine and rapid, intensified with sustained posture (such as holding hands extended), relieved by alcohol, and is usually familial with onset in young adulthood

· head tremor may also be seen

· treatment: propranolol 20-60 mg tid or diazepam 2-10 mg tid (The medications that are effective in treating parkinsonism have no effect on essential tremor.)

Transient ischemic attack (TIA)

Cerebrovascular disease

A. Infarction

1. TIAs

2. Progressing stroke

3. Completed stroke

4. Lacunar infarction

B. Intracranial hemorrhage

1. Intracerebral hemorrhage

2. Subarachnoid hemorrhage (SAH)

Vertigo

Classification:

. Vertigo: a sense that the environment is spinning around or a sensation of feeling impelled forward, backward, or to either side

. Presyncope: a feeling of light-headedness or faintness

. Disequilibrium: dizziness is primarily experienced when one is standing or walking

Vertigo syndromes: Causes of recurrent episodes of vertigo

. Benign paroxysmal positional vertigo (BPPV):

. Positioning vertigo:

. Meniere’s disease:

. Toxic damage to labyrinth

. Acoustic neuroma

. Migraine

. Perilymph fistula

. Temporal lobe epilepsy

Vertigo syndromes: Causes of a single acute episode of vertigo

. Acute peripheral vestibulopathy (viral labyrinthitis)

. Vertebrobasilar vascular disease

. Multiple sclerosis

. Head trauma (postconcussion syndrome)