Can your neck pain make everywhere "spinny"

While the influence of neck position on equilibrium  has been known and documented since 1800s, it is often difficult to assume any relationship in situations of neck pain or stiffness associated with dizziness. 

That was until 1955 when Ryan & Cope described a syndrome of disequilibrium and disorientation in patients with many different diagnoses of neck pathology including cervical spondylosis, cervical trauma, and cervical arthritis. They labelled this syndrome cervical vertigo. 

A flurry of publications on cervical vertigo was to follow. The argument for the existence of this diagnosis was premised on the fact that Proprioceptive input from the neck participates in the coordination of eye, head, and body posture as well as spatial orientation. 

However, the interesting fact is that true spinning vertigo is rarely associated with this disease,making some worker to suggest alternative diagnosis of cervicogenic dizziness for this condition. 

Also interesting is the fact that  while some entities previously defined as cervical vertigo have survived the test of time and may be found in the literature today for example  rotational vertebral artery syndrome, post-traumatic cervical vertigo, and cervicogenic proprioceptive vertigo, others such as cervical sympathetic syndrome (Barré-Lieou syndrome), have been discredited. 

It was also subsequently elaborated that since neck contains mechanisms directly involved in balance control (neck afferents), cardiovascular control (carotid bodies), and purely vascular structures (carotid and vertebral arteries), and since neck movements are also invariably associated with head movements, then perhaps experiencing unsteadiness or vertigo associated with neck movements could be due to a disorder in vestibular, visual, vascular, neurovascular, or cervicoproprioceptive mechanisms.

The interesting aspect of this exposition is that currently there is no consensus concerning how one diagnoses cervical vertigo, and the literature is replete with poorly carried out studies as well as studies containing strange suggestions regarding mechanism or treatment.

As such the publications on "cervical vertigo" has plummeted in the last half decade. 

         

References:

1. J Neurol Neurosurg Psychiatry 2001;71:8-12 doi:10.1136/jnnp.71.1.8

2. Neurologia. 2012 Sep 13. pii: S0213-4853(12)00211-3. doi: 10.1016/j.nrl.2012.06.013

3. Cervicogenic Dizziness. http://vestibular.org/cervicogenic-dizziness

4. Cervical Vertigo. http://www.dizziness-and-balance.com/disorders/central/cervical/cervical.html 

Will HNS replace CPAP in OSAS?

Obstructive sleep apnoea syndrome (OSAS) is characterized by repeated episodes of pharyngeal obstruction during sleep, including airway collapse or narrowing resulting in recurrent airflow cessation. 

Identified risk factors include obesity, male sex, Craniofacial and upper airway anomalies, increasing age, and alcohol consumption. 

Traditional  approach to treating OSAS focused on weight reduction (occasionally easy to prescribe, but hard to comply with), removal of obstructive airway lesions (adenotonsillectomy), palatal implants, mandibular advancement surgery (for retrognathia), our own UPPP (uvulopalatopharyngoplasty)  and of course the popular (GPs) option - the CPAP. The interesting fact is compliance rate with CPAP is just about 40-60% (can you stand mask and tubes coming between you and your spouse while on bed?). 

Recent interest in OSAS focuses on genioglossus muscle as therapeutic target, for simple reason: if you get the tongue out of the way, the oropharyngeal airway blockage is removed. 

Devices that stimulate this muscle directly were demonstrated to improve disease severity in OSAS sufferers. However, the interesting aspect is that such direct stimulation would often arouse the patient!!!

This led to the choice of targeted electrical stimulation of the hypoglossal nerve which is directly motor to the genioglossus fibers, with little or no sensory innervation. 

The Hypoglossal Nerve Stimulation (HNS) system is currently undergoing trials in several countries and may be the next interesting toy for treatment of OSAS, though its current cost puts it far beyond the reach of all but very endowed OSAS cases with mild to moderate ( not severe) OSAS. Maybe for severe OSAS, we are stuck with CPAP for some time to come!!!

References:

1. Health Policy Advisory Committee on Technology - Technology Brief: hypoglossal nerve stimulation for sleep apnoea. http://health.qld.gov.au/healthpact/docs/briefs/WP097.pdf

2. Cure Opin Pulm Med. 2011;17(6):419-424

Confusion from Ear-Brain Dissociation

Auditory neuropathy spectrum disorders (ANSD) is an interesting relatively recent diagnosis whose recognition was made possible by advances in electrophysiologic acoustic measurement, specifically the ABR and the OAE. However the interesting fact was the first audiologic description of ANSD was believed to be by Hinchcliffe et al in 1972, six years before Kemp described Otoacoustic emissions. 

ANSD is characterized by normal OAES, presence of cochlear microphonics, absent middle ear muscle reflexes at 95 dB and below, and abnormal ABR. In simple terms, the brain in ANSD appears to be detached from the auditory pathway and /or the inner ear appears not to communicate with the auditory nerve (depending on the variant). 

ANSD is believed to consist of variant of disorders with lesions in either of several locations - inner hair cells, inner hair cell-auditory nerve synaptic junctions and the ascending auditory neuron. 

The other interesting aspect is in the nomenclature itself. A neuropathy usually refers to a disease of the peripheral nerve or nerves, but the auditory nerve itself is not always affected in Auditory Neuropathy Spectrum Disorder (ANSD). Also while the pure tone audiometry finding may vary from normal to near normal, there is consistent difficulty in perceiving speech in ANSD. 

Also referred to as auditory dyssynchrony, numerous risk factors reportedly associated and varying clinical presentation characterizing ANSD make the management options also as varied and controversial. Hearing aids and cochlear implants have been prescribed for ANSD with mixed outcome. Current effort is geared towards developing animal models that can precisely replicate findings in ANSD cases to assist further understanding and better management approach. 

References:

1. Auditory Neuropathy. Emedicine. http://emedicine.medscape.com/article/836769-overview 

2. Multi site diagnosis and managent of 260 patients with ANSD. http://csd.cbcs.usf.edu/an/Berlin_ANSD.pdf 

Ssssooo Mmmmmumumuch To Tttttalk Abababout

Normal speech production involves a balanced coordination between muscle movements involving breathing, phonation (voice production), and articulation (movement of the throat, palate, tongue, and lips). The speech cycle essentially incorporates input (hearing, vision, proprioception), central processing (receptive and expressive speech areas of the brain) and output (phonation, articulation and resonation). 

The precise mechanism of what led to stuttering is unknown but has long been thought to be disorder of the central speech processing. The advent of advanced imaging techniques  like PET Scan and functional MRI in investigation of stuttering revealed interesting facts that people who stutter show  hypoactivity in cortical areas associated with language processing, such as Broca's area, but hyperactivity in areas associated with motor function. 

A puzzling aspect of stuttering is the various conditions which can temporarily alleviate dysfluency in most cases: the rhythm effect (speaking to the pace of a metronome), singing (remember the dude at just-ended American Idol season?), chorus speech, and altered auditory feedback.  Another interesting aspect of stuttering is that in some sufferers, there is spontaneous resolution either during childhood, or even during adult life! But we currently have no clue as to in which subject stuttering will spontaneously resolve. Another interesting fact is that this recovery can be induced by therapy in few cases. Both spontaneous and assisted recoveries also appear to be heritable. More interesting still is  that children with early onset of stuttering tend to show precocious language development.

Stuttering, long thought to be largely psychogenic is now believed to consist of 3 types - developmental, neurogenic and functional. 

Further Readings:

1. Journal of Communication Disorders 37 (2004) 325–369

2. Stuttering 

http://www.medicinenet.com/stuttering/article.htm

3. How the brain repair stuttering. http://m.brain.oxfordjournals.org/content/132/10/2747.long 

Stop that Q-tip, Please!

It is commonplace for clinicians to counsel patients against use of cotton buds or Q-tips to clean the ear. 

The reason for such advice lies in the unique situation of the epidermis lining the external ear canal. 

Whilst epidermis lining the surface of skin elsewhere in the body is subjected to friction (surface contact) to remove keratinocytes that have desquamated from the surface stratum corneum, evolution of deeper ear canals in land animals for protection of tympanic membrane presents a challenge for achieving that 'shedding of skin'. 

This implies an alternative mechanism  of removal of the superficial layer of stratum corneum of the tympanic membrane and the protected deep portion of EAC. 

The interesting fact is that while skin cells elsewhere migrate vertically from the dermis to the epidermis (epithelial maturation), the ear canal skin, in addition, works like a 'conveyor belt' migrating the skin cells from the center of ear drum (tympanic membrane) outwards along the ear canal. This rate of this 'conveyor belt' motion is timed to coordinate rate of normal epithelial maturation. 

Hence the instruction on the box of Q-tip: only use around outside of ear canal. 

Reference:

1. An Ode To Ear Wax. http://variationselectioninheritance.podbean.com/2012/03/10/episode-35-an-ode-to-earwax/

2. Physiology of The Ear. Google Books. http://books.google.co.uk/books?id=giFuKH5u7O0C&pg=PA30&lpg=PA30&dq=ear+canal+skin+migration+evolution&source=bl&ots=x-RdGPxYrE&sig=9_oRdcdtA-cFjv-ZfZxcitlad28&hl=en&sa=X&ei=97rGUfa0AebE0QW7w4D4Cw&ved=0CCoQ6AEwAA

 

When Your Voice Makes Me Dizzy...!

We occasionally encounter subjects complaining of dizziness or vertigo that is induced by noise. The exact phenomenon of sound-induced vertigo was little described in medical literature until the celebrated observations of Prof. Pietro Tullio, an Italian biologist in 1929. 

Tulio's phenomenon as it was subsequently called has since been described in 5 otological conditions - Superior canal dehiscence, perilymph fistula, Meniere's syndrome, post fenestration surgery, and vestibulofibrosis. 

The interesting aspect is that the original Tullio's experiment observed by drilling tiny holes in the semicircular canals of pigeon was meant to demonstrate sound-induced vestibulopathy. 

Now, the real interesting aspect is that we do not have a single explanation as to the exact mechanism of this phenomenon. Rather what we have are explanations of possible mechanisms each peculiar to specific disease entity. 

Tullio's phenomenon is also now known to be either physiological or pathological. The physiologic Tullio's can be elicited when very loud pure tone sound is presented monaurally, or clicks at 110 decibel  to a blindfolded subject on posturographic platform. 

The pathologic Tullio's on the other hand are elicited by less loud sound (<70dB nHL) for clicks, or by loud pure tones presented binaurally. 

Pathological modifiers suspected in Tullio's phenomenon include pathological contiguity of the tympano-ossicular chain and membranous labyrinth, dislocated ossicular chain, stapes hyperlaxity, fracture of the footplate or of the labyrinth, fibrotic damping of the ossicular chain, fibrosis of the inner ear, traumatic labyrinth, perilym- phatic fistula and endolymphatic hydrops.

References:

1. B-ENT, 2008, 4, Suppl. 8, 27-28

2. http://www.dizziness-and-balance.com/disorders/symptoms/tullio.html 

Searchlight on Otoliths!

That the vestibular organ consists of the semicircular canals and the otoliths organs is a well known fact. That most of the conventional  battery of tests of vestibular function assess the semicircular canals mainly the lateral SCC is another facts known to few. 

The otolith organs - the utricle and saccule sense linear acceleration, head tilt and gravity (yeah! that kind of lift going up/coming down feeling). 

What is also interesting is that in lower vertebrates, especially amphibians and fish, the saccule is also sensitive to sound, and is the organ of hearing! In our species, the cochlea has evolved to replace the saccule as the primary organ of hearing. 

Until recently, clinical tests to measure the otolith function were not available, largely due to cumbersome nature of such gadgets (picture a mini railway track with vestibular chair strapped and all the cables to your VNG! Or picture a lab fitted with a vertical lift fitted with all these!) as well as difficulty, even with such gadgets, to selectively stimulate unilateral otolith function. 

That was before VEMP and Subjective Visual Vertical (SVV) were introduced as tests of saccule and utricular functions respectively. 

Assymetry between the left and right otolith organs contributes to an astronaut's individual susceptibility to space motion sickness (SMS) - a phenomenon seen in 50-70% of astronauts during first days of spaceflight. 

References:

1. J Vestib Res. 2011;21(3):141-51. doi: 10.3233/VES-2011-0400.

2. http://www.asha.org/Publications/leader/2009/090210/f090210b/

Better in Noise, Worse in Noise!

Hearing loss has been reported since early documentation of medical knowledge, and several categorization exist based on etiology, severity, laterality, pathology, degree of handicap, and time of onset. 

Of interest to hearing care physician is the phenomena of hearing in noise, of which there were 2 types:

1. Hard-of-hearing patients hear conversations better in noise

2. Hard-of-hearing patients hear conversations worse in noise

While the latter is seen commonly with one ear hearing situation (unilateral hearing loss) and can be easily explained based on our understanding of the auditory pathway, the first phenomenon was not easy to explain (ever heard or read about the legend of the deaf woman who can only hear when someone is beating the drum?). 

The first phenomenon was first described by Willis in 1672, and together With the observation that such hard-of-hearing patients also perceive constant signals better in noise, is referred to as paracusis willisii. The explanation for the phenomenon of paracusis willisii was to occupy physicians for another 3 centuries until Politzer  (1901), Lombard (1911) and Jenkins (1938), Lowenberg and Urbantschitsch, Siebenmann and Von Tröltsch  made interesting attempts. 

Various explanations put forward for this phenomena include:

1. General vibration of the loose ossicular chain (Politzer)

2. Production of increased irritability of the acoustic nerve (Jenkins, Lowenberg and Urbantschitsch)

3. Background noise is low pitched, not well heard by patient, while normal observer in conversation with patient raises his voice (Lombard, Sibenmann & Von Tröltsch). 

Variations of Paracusis willisii was reported by Hastings & Scarf in 1928 (relative paracusis, absolute paracusis) and this interesting observation continue to form important diagnostic indicator for otosclerosis. 

References:

1. Proc R Soc Med. 1928 February; 21(4):611-616

2. Laryngoscope 1952 vol. 62(7) pp. 678-703

Sweet smell, Tasty Odour!

We perceive taste when nutrients or other chemical compounds activate specialised taste receptor cells located in our oral cavity, and the sense of taste is believed to have evolved to help our species decide what to eat and how efficiently we digest these. 

Smell on the other hand results when the odourants come in contact with olfactory receptors located along superior and middle turbinates and the upper part of nasal septum. From evolution point of view, the sense of smell is believed to have preceded that of taste, since pre-mammals are known to have much larger brain areas associated with smell. Smell is known to have driven most of the early expansion of the brain in proto-mammals and in the last common ancestor of living mammal species. 

The interesting aspect is the perceptual confusion in our species. between the senses of smell and taste (together called chemical senses), manifested on one hand in attribution of taste qualities to odours, and on the other the enhancement of taste intensities by odours. 

The degree to which an odour smells sweet has been found to be a predictor of the degree to which same odour will enhance or suppress the sweetness of sucrose.

Reference:

1. Nature News 20 May 2011 Last updated at 09:08

2. Current Biology, Volume 23, Issue 9, R409-R418, 6 May 2013

3. Chem. Senses (1999) 24 (6): 627-635. doi: 10.1093/chemse/24.6.627

4. New York Times Book - The Sense of Smell. http://www.nytimes.com/books/first/v/vroon-smell.html 

Not all that is grayish is Cholesterol!

Do you know that cholesteatoma was first described by Cruveilhier in 1829, but first named by Müller in 1828?

And that its discovery has lead to myriads of ear surgery techniques ranging from 'Canal wall down' mastoidectomy (early half of 20th century), through the 'Combined approach, intact canal wall' tympanomastoidectomies (William & Howard House, 1950s-60s), to 'Canal wall through' technique, and finally to individualized treatment approach?

The interesting aspect is that the term cholesteatoma (used for grayish lesion within the middle ear (and/or the external ear) with expansile tendencies) was based on previous misconception that it contained cholesterol in its substance. This is currently found to be untrue, but then we are stuck with the term Cholesteatoma 

Spite the tongue, Save the face!

Do you know that Otorhinolaryngologists occasionally 'sacrifice' the 12th cranial nerve (hypoglossal, responsible for tongue movement) in order to repair the damaged facial nerve?

Such surgery often results in severe tongue hemiatrophy. 

This technique of classical facial reanimation has been used for over 100 years since original description by Korte in 1903. The technique was refined in 1997 when partial direct hypoglossal - facial anastomoses was described. 

Reference:

Surg Neurol Int 2012, 3:46