Where in the World is Bill’s Bar?

Bill’s Bar is an internationally famous place.  This week at Hearing international we will tell you where to find the famous Bill’s Bar and its significance to Audiology. Bill’s Bar might sound like a fun place with a band, great beer and other fun beverages. You might expect to go there to meet friends, family and just other people, play pool, darts…….but NOT SO FAST.

Where IS Bill’s Bar

 In Audiology and Otology, Bill’s Bar has a totally different meaning.  It’s not a REAL bar, but a landmark within the auditory system. Audiologists who monitor surgeries, and Otologists, Otolaryngologists and Neurotologists who perform Acoustic Neuroma surgery all know Bill’s Bar as one of the famous landmarks in the procedure.

Bill’s Bar is not located on Broadway or  First Street –  it is located within the skull at the internal auditory meatus (IAM), a canal within the temporal bone that transmits nerves and vessels from the posterior cranial fossa to the auditory apparatus. Contents of the IAM include:

• facial nerve
• vestibulocochlear nerve, sometimes called Scarpa’s Ganglion
• vestibular ganglion
• labyrinthine artery (usually a branch of the basilar artery)

The opening of the IAM is located within the cranial cavity, near the posterior surface of the temporal bone. The margins of the opening are smooth and rounded and the canal is short (1 cm), running laterally to the bone. At the distal end of the canal, it splits into three distinct openings, one of which is the facial canal.  There are five nerves that run through the IAM:

• nervus intermedius (sensory component of CN VII)
• facial motor root (motor component of CN VII)
• cochlear nerve (component of CN VIII)
• inferior vestibular nerve (component of CN VIII)
• superior vestibular nerve (component of CN VIII)

Their position is most constant in the lateral portion of the meatus which is anatomically divided by the falciform crescent. This horizontal ridge divides the canal into superior and inferior portions, where superiorly lie the facial nerve and the superior vestibular nerve (SV).  The facial nerve (7) is anterior to the SV and these nerves are separated laterally by Bill’s bar, a vertical ridge of bone also called the vertical crest (VC). Inferior lies the cochlear nerve and inferior vestibular nerve (IVN); the cochlear nerve is situated anterior to the IV.

 Significance of Bill’s Bar

Bill’s Bar is named for Dr. William “Bill” House, a pioneer in otologic surgery, inventor of the cochlear implant and the father of Neurotology. In 1965, Dr. House pioneered the Translabyrinthine Approach to acoustic neuroma surgery and revolutionized the procedure for removal of troublesome, hard-to-excise acoustic tumors.  In the early 1960s, prior to the development of the translabyrinthine approach, acoustic neuromas were treated by means of a suboccipital approach without the aid of an operating microscope. Patients who underwent acoustic neuroma surgery at that time had a 40% chance of dying on the operating table.

While today’s acoustic neuroma surgical techniques include other procedures that are used for various clinical reasons, the translabyrinthine approach practically eliminated the risk of mortality for acoustic neuroma surgery.  Today, the danger of dying from acoustic neuroma surgery is 1% in the United States and greatly reduced around the world in the hand of skilled surgical professionals.  While the translabryinthine approach is the oldest successful technique in use for acoustic neuroma surgery, it still  provides the best line of sight and access to the facial nerve and, consequently, offers the highest rate of success in facial nerve preservation, especially for large tumors. The downside of the translabyrintine approach is that using the procedure means sacrificing the patient’s hearing.  Most surgeons consider this approach when a patient has severe hearing loss with poor speech understanding ability and/or the tumor is too large (above 20 mm) for hearing preservation surgery.  Some of the other procedures used for acoustic tumor removal require brain compression, but with the translabyrinthine approach brain retraction is not necessary, which often makes it the safest choice.

In these surgical procedures, one of the major landmarks is the vertical crest, now called Bill’s Bar after one of the most inventive otologic surgeons of all time, Dr. William F. House. Dr. Bill to his friends and colleagues, was a founder of the House Ear Institute in Los Angeles. He died in December 2012.