Cranial Nerve Anatomy and Testing
These four cranial nerves (CNs) mediate the cranial outflow of the parasympathetic nervous system.
What are CN III, CN VII, CN IX, and CN X?
This paraneoplastic syndrome is caused by autoimmune destruction of presynaptic calcium channels and is often associated with small cell lung cancer.
What is Lambert-Eaton Myasthenic Syndrome (LEMS)?
A lesion to the Wernicke area in the dominant hemisphere causes this type of aphasia, characterized by fluent speech but difficulty in comprehension.
What is Wernicke's aphasia (or receptive/sensory aphasia)?
This amino acid neurotransmitter is the major inhibitory neurotransmitter in the CNS and is elaborated by the GABAergic Purkinje cells of the cerebellum.
What is GABA (Gamma-aminobutyric acid)?
This life-threatening, idiosyncratic reaction to antipsychotic drugs is characterized by generalized muscular rigidity ("lead-pipe rigidity"), hyperthermia, and altered mental status, which may be treated with dantrolene or bromocriptine.
What is Neuroleptic Malignant Syndrome (NMS)?
The Oculomotor (CN III), Trochlear (CN IV), and Abducens (CN VI) nerves, along with the ophthalmic division of the Trigeminal nerve (V1), all pass through this cranial opening or fissure.
What is the superior orbital fissure?
This acute autoimmune disease targets the myelin in the peripheral nervous system and often follows an infection, leading to ascending paralysis and elevated CSF protein with a normal CSF cell count.
What is Guillain–Barré Syndrome (GBS) or Acute Inflammatory Demyelinating Polyneuropathy (AIDP)?
This primary headache is described as being bilateral and band-like.
What is a Tension Headache?
This is the major neurotransmitter of the parasympathetic nervous system, used for both preganglionic and postganglionic synapses
What is Acetylcholine (ACh)?
This syndrome includes mental status changes, autonomic instability, and neuromuscular abnormalities from serotonergic drugs.
What is serotonin syndrome?
To isolate the superior oblique muscle, which is innervated by CN IV, the patient should be instructed to perform this specific eye movement.
What is looking in (adduct) then down?
The symptoms of Myasthenia Gravis are typically due to the presence of antibodies targeting this specific receptor at the neuromuscular junction.
What is the nicotinic acetylcholine receptor?
This potentially reversible condition presents with the classic triad of gait disturbance, urinary incontinence, and cognitive impairment.
What is Normal Pressure Hydrocephalus (NPH)?
Parkinson disease is characterized by the loss of neurons elaborating this neurotransmitter in the pars compacta of the substantia nigra.
What is Dopamine?
Schizoaffective disorder includes features of schizophrenia plus this type of disorder.
What is a mood disorder (major depressive or manic episode)?
This specific division of the Trigeminal nerve (CN V) mediates the afferent limb (sensory input) of the corneal reflex.
What is the Ophthalmic division (CN V1)?
This universally fatal prionopathy is associated with rapidly progressive dementia and periodic bursts of high voltage sharp waves on EEG.
What is Creutzfeldt-Jakob Disease (CJD)?
This syndrome is caused by bilateral lesions of the amygdala, resulting in symptoms such as hyperphagia, hypersexuality, and psychic blindness (visual agnosia).
What is Klüver-Bucy Syndrome?
This indolamine neurotransmitter, produced by the Raphe nuclei, is often found at low levels in patients suffering from depression.
What is Serotonin (5-HT)?
Pinpoint pupils, respiratory depression, and unconsciousness suggest overdose of this substance.
What are opioids?
A lesion to the Vagus nerve (CN X) results in paralysis of this structure, causing it to deviate away from the side of the lesion
What is the uvula (or soft palate)?
This syndrome involves severe demyelination in the central pons, caused by the rapid correction of chronic hyponatremia, and may lead to locked-in syndrome.
What is Central Pontine Myelinolysis (CPM) (or Osmotic Demyelination Syndrome [ODS])?
This cognitive deficit is distinguished from dementia by its acute onset and fluctuating symptoms.
What is Delirium?
This movement disorder, characterized by repetitive choreic movements of the face, limbs, and trunk, can result from treatment with antipsychotic drugs that antagonize dopamine.
What is Tardive Dyskinesia?
This antipsychotic has the lowest risk of extrapyramidal symptoms but the highest metabolic risk.
What is clozapine?