This type of paralysis produces palsy of superior oblique muscle resulting in limitation of downward movement of eye when it is in adducted position; it is frequently associated with third cranial nerve palsy.

1. Intracerebral

 A. Thrombosis of nutrient vessels, including median penetrating branch of basilar artery to  fourth nucleus
 B. Hemorrhage in the roof of the midbrain
 C. Aneurysm, including direct involvement by posterior cerebral and superior cerebellar arteries
 D. Tumors (rare if isolated fourth palsy)
  (1) Primary
   a. Gliomas, such as astrocytomas, ependymomas, and medulloblastomas
   b. Other primary tumors, including meningiomas, pinealomas, craniopharyngiomas, and hemangiomas
  (2) Unilateral trochlear nerve palsy
 E. Metastatic lesions, such as those from the nasopharynx, rhabdomyosarcomas,  and neuroblastomas
 F. Neonatal hypoxia
 G. Nuclear type-trochlear paresis combined with a homolateral oculomotor  paresis, occasionally in association with vertical gaze palsies, convergence spasm  or convergence palsy, and pupillary disturbances seen in tumors of the roof of the  midbrain or pinealomas (pineal syndrome)
 H. Claude syndrome (inferior nucleus ruber syndrome)
 I. Passow syndrome (syringomyelia)
 J. Inflammatory lesions, such as meningoencephalitis, cerebellitis, and abscess
 K. Pseudotumor cerebri

2. Intracranial

 A. Aneurysms, such as that of the posterior communicating artery or foramen  lacerum syndrome (aneurysm of internal carotid artery syndrome)
 B. Hematomas, traumatic
 C. Hydrocephalus
 D. Meningitis, encephalitis, polyneuritis-diabetes mellitus, herpes zoster, multiple  sclerosis, myasthenia gravis, chickenpox, diphtheria, hydrophobia, Gradenigo  syndrome, influenza, malaria, poliomyelitis
 E. Trauma
 F. Tumors, including cerebellopontine angle tumor and pituitary adenoma
3. Lesions affecting exit from cranial cavity
 A. Cavernous sinus syndrome (Foix syndrome)
 B. Superior orbital fissure syndrome (Rochon-Duvigneaud syndrome)
 C. Orbital apex syndrome (Rollet syndrome)

4. Orbital lesions

 A. Fracture of superior orbital rim
 B. Sinusitis
 C. Operations on the frontal sinus in which there is trochlear displacement
 D. Trochlear disturbance, such as in Paget disease or hypertrophic arthritis
 E. Adherence syndrome-adhesions between the superior rectus and superior  oblique muscles
 F. Abnormal insertion of superior oblique muscle or abnormal fascial attachments
 G. Rochon-Duvigneaud syndrome (superior orbital fissure syndrome)
 H. Idiopathic

Extracted Table Paralysis of fourth nerve

Feinberg AS, Newman NJ. Schwannoma in patients with isolated unilateral trochlear Nerve palsy. Am J Ophthalmol 1999; 127:183-188.

Holmes JM, et al. Pediatric third, fourth, and sixth nerve palsies: a population-based study. Am J Ophthalmol 1999; 127:388-392.

Keane JR. Fourth nerve palsy: historical review and study of inpatients. Neurology 1993; 43:2439-2433.

Peterman SH, Newman NJ. Pituary macroadenoma manifesting as an isolated fourth nerve palsy. Am J Ophthalmol 1999; 127, 2:235- 236.

Roy FH. Ocular syndromes and systemic diseases, 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2002.

Speer C, et al. Four cranial nerve palsy III pediatric patients with pseudotumor cerebri. Am J Ophthalmol 1999; 127: 236-237.

Childhood Causes of Fourth Nerve (Trochlear) Palsy

1. Trauma
2. Neoplasm
3. Undetermined
4. Postoperative cause
5. Meningitis
6. Hydrocephalus
7. Ophthalmoplegic migraine
8. Viral infection
9. Aneurysm
10. Other

Holmes JM, et al. Pediatric third, fourth, and sixth nerve palsies: a population-based study. Am J Ophthalmol 1999; 127:388-392.

Kodsi SR, Younge BR. Acquired oculomotor, trochlear, and abducent cranial nerve palsies in pediatric patients. Am J Ophthalmol 1992; 114:568-574.