Temporal bone histopathology: Resident's quiz

Am J Otolaryngol 11:357-359.

1990

Temporal

Bone Histopathology: Resident’s Quiz

MITCHELL S. MARION, MD, AND RAUL HINOJOSA, MD, EDITORS week later, the results of isoelectric electroencephalogram prompted the patient’s transfer as a kidney donor to a major medical institution. At autopsy, anatomic diagnoses included multiple arterial stenoses, portal fibrosis with esophageal varices, intracranial hemorrhage, and neurofibromatosis. There was no available clinical or historical information with regard to his ears. Both temporal bones were available for histologic study, and the findings were similar in each. What is your diagnosis?

CASE REPORT

In 1965, a 17-month-old boy presented with hematemesis, splenomegaly, and iron deficiency anemia. An aortogram revealed occlusion of the right subclavian and superior mesenteric arteries. The only therapy instituted was antihypertensive medication. At age 11, he developed a severe headache followed by several grand ma1 seizures. He was hospitalized in a comatose state. One

Figure

Key to Figures 1 through 4: C, cochlea; CA,carotid nerve;

M, malleus;

RWM.

round

window

membrane;

1

EAM,external auditory meatus; FN, facial SA, stapedial artery; ST, stapes; TTM, tensor

artery;

357

nerve; I, incus; JN, Jacobsen’s tympani muscle.

QUIZ

358

Figure 2

DIAGNOSIS Persistent

stapedial

artery.

HISTOPATHOLOGY A direct communication of the stapedial artery with the internal carotid artery was identified 9.5 mm below the hypotympanum. Leaving the carotid canal, the stapedial artery coursed upward and posteriorly, indenting the otic capsule to gain entrance into the middle ear. Nerve fibers, originating from the sympathetic plexus, surrounding the internal carotid artery, traveled with the stapedial artery. Contained within a bony canal, the artery entered the anterior hypotympanum and then continued to course upward, crossing, and briefly occupying, Jacobsen’s canal. The artery ascended along the promontory enclosed in a bony canal (Fig 1). Superior to the round window, the artery left the promontory to move further upward and occupy its classic position between the stapes crura (Fig 2). Continuing to ascend, the artery entered a defect in the facial canal just behind the cochleariform process, and traveled with the seventh nerve to its hiatus. Contained in a bony canal, it arched upward and forward over the tensor tympani muscle, and then emerged into the middle cranial fossa, lying on the anterior face of the petrous apex. From here, the artery coursed downward to an area normally occupied by the middle meningeal artery, and then finally divided into three terminal branches, each of which moved laterally in the dura toward the squamous portion of the temporal bone, following the course

of the middle meningeal artery. No foramen spinosum was identified in this specimen, and it is thought that the persistent stapedial artery substituted for the middle meningeal in this case. Twodimensional reconstruction of the artery is graphically depicted in Figs 3 and 4. DISCUSSION Stapedial artery persistence apparently occurs in only one in 5,000 to 10,000 cases.l Since discovery of this artery in 1836 by Hyrtl,’ less than 30 cases of its persistence have been published. Many of these were clinical descriptions in which the author recognized the artery only as an accidental event at the time of surgery. There are few reports on the histopathology of this anomaly.3 Normally, no remnant of the stapedial artery persists in man. Broman4 observed that the stapedial artery identified in a 55 mm embryo atrophies ,staaedial artery superficial stylomastoid artery

petrosal artery

superior tympanic

stapes facial nerve

‘jugular

fossa

Finure 3

359

MARION AND HINOJOSA

Figure 4

into only a strand of fibrous tissue in the 90 mm embryo. When the 180 mm stage is reached, no trace of the stapedial artery can be identified. During development, the stapedial artery has two branches, an upper branch that forms the middle meningeal and a lower division that develops into the inferior alveolar and infraorbital vessels. When the stapedial trunk atrophies, these two branches become supplied by a new communication with the external carotid artery. It is this transition that allows the stapedial artery to atrophy. However, if this transition fails to occur, then the middle meningeal continues to be supplied by a persistent stapedial artery. In keeping with this theory, in a case reported by Guinto et a1,5 a right carotid arteriogram revealed a stapedial artery which arose from the internal carotid, pierced the temporal bone, and appeared in the middle cranial fossa as the middle meningeal artery. The developmental process by which the stapedial artery assumes the position between the

stapes crura was studied by Strickland et al6 Apparently, the ossicular anlage folds around it. That is, the artery does not pierce the stapedial blastema, rather, the blastema is influenced by the existing artery. Thes68adult stapes, therefore, is, i n part, an artifact of the stapedial artery. Little is known about the clinical implications of stapedial artery persistence. In 1958, Kelemen7 proposed that, because the stapedial artery course is close to the base of the cochlea, it may be a source of tinnitus. However, in two reported cases by House and Patterson,* the stapedial artery was clinically silent. Usually, a persistent stapedial artery is encountered only accidentally at the time of surgery. This may prompt the surgeon to terminate the procedure. Hogg et al9 has stated that theoretically clamping the stapedial artery may induce a transitory crossed hemiplegia. No such case has been reported. Most often, negligence of a large persistent stapedial artery results in profuse bleeding. References 1. Schuknecht H: Pathology of the Ear. Cambridge, MA, Harvard University Press, 1974, pp 186-187 2. Hyrtl J: Neue Beobachtungen aus dem Gebiete der menschlichen und vergleichenden Anatomie. Med Jahrb Oesterreich, Staates 1836; 10:457-466 3. Marion MS, Hinojosa R: Persistence of the stapedial artery: A histopathologic study. Otolaryngol Head Neck Surg 1985; 93:298-312 4. Broman I: Die Entwicklungsgeschiechte der Gehorknochelchen beim Menschen. Anat Hefte 1898; 11:507-668 5. Guinto F, Garrabrant EC, Radcliffe WB: Radiology of the persistent stapedial artery. Radiology 1972; 105:365-369 6. Strickland EM, Hanson JR, Anson BJ: Branchial sources of auditory ossicles in man. Arch Otolaryngol 1962; 76:100122 7. Kelemen G: Arteria stapedia in bilateral persistence. Arch Otolaryngol 1958; 67:668-677 8. House HP, Patterson ME: Persistent stapedial artery: Report of two cases. Trans Am Acad Ophthalmol Otolaryngol 1964; 68:644-646 9. Hogg ID, Stephens CB, Arnold GE: Theoretical anomalies of the stapedial artery. Ann Otol Rhino1 Larvneol _ ” 1972: 82:860870 -