Selects: How Itching Works

The sensation of itch has long intrigued and puzzled scientists and historians. Only in recent decades has the research around itch matured enough to reveal the unique neurological mechanisms behind this common yet complex feeling.

Early Definitions and Theories of Itch

Samuel Hoffenreffer's Itch Definition, 1660

Itch has been recognized for centuries as a distinct sensation, with historical references to its unique nature.

Itch Considered a Unique Sensory Experience With Specialized Neural Pathways Since the 1980s

H.O. Handwerker's pioneering studies in the 1980s ignited a shift in understanding of itch as a unique sensory experience with specialized neural pathways. Before his work, it was thought that an itch was simply a low-grade pain stimulus. However, Handwerker and his team's experiments -- applying histamine directly to subjects' skin along with electrical stimulation -- revealed that even with increased doses, participants reported only an intense itch and never pain. This led to the recognition that itch traveled via pathways distinct from those of pain.

Neuroscience Reveals Neurological Mechanisms of Itch Sensation

Advancements in neuroscience have gradually unveiled the enigmatic mechanisms behind itch sensation.

Itch Signals Travel From Skin To Brain Via Specialized "C-Fiber" Nerves, Distinct From Pain Receptors

Josh Clark points out that our understanding of itch is relatively recent, with ongoing research continuing to unravel its mysteries. Key findings detail that itch signals are transmitted from the skin to the brain through specialized "C-Fiber" nerves, which are separate from pain receptors. Of these C-fibers, only about 5% are dedicated to hand ...

The itch-scratch cycle, a seemingly commonplace phenomenon, actually harbors a complex neurological interchange involving both sensory and emotional components of the human experience.

Scratching Activates Nerve Receptors for Temporary Relief but Worsens the Itch

Scratching serves as a temporary solution to the discomfort of an itch. Not only is it an irresistible urge likened to the compulsions seen in addiction cycles, but this behavior also activates a specific pattern in the brain that intertwines the sensation of itching and the consequential need to scratch.

Scratching Releases Serotonin, Intensifying the Itch

When one gives in to the urge to scratch, the skin’s nearby non-itch receptors are stimulated, sending feedback to the brain that relief is underway. This feedback yields a brief respite from the itch. However, this action simultaneously releases serotonin, which, although normally beneficial as a mood enhancer and pain reliever, actually exacerbates the sensation of itching. Therefore, the itch not only returns but often in a heightened state, leading to an intensified cycle of itching and scratching.

Addictive Cycle: Irresistible Need to Scratch as Itch Worsens

The regions of the brain that activate during this cycle include emotional centers experiencing the displeasure from the itch, limbic areas that process urges, and motor regions that spur the need to scratch. Together, these areas contribute to the itch-scratch cycle, where scratching provides momentary relief but the serotonin released worsens the itch, fostering an irresistible and vicious cycle.

Researchers Still Working to Understand This Cycle's Neurological Basis

Researchers continue to delve into the neurological basis of this itch-scratch cycle, encountering difficulties in treating persistent itches without disrupting other bodily functions.

Itch Receptors Detect Stimuli Inches Away, Causing Persistent Itching

Treatment for chronic itches is complex as it involves chemistries, like the neu ...

Podcast hosts Chuck Bryant and Josh Clark discuss experiences with contact dermatitis and severe itching management, raising awareness of how severely this condition can affect quality of life.

Podcast Hosts Discuss Contact Dermatitis Experiences and Severe Itching Management

Chuck Bryant recounts his struggle with intense itching caused by contact dermatitis, possibly from cement, and his efforts to manage it.

Cement Dermatitis Caused Itching, Requiring Steroids and Showers

While building a gate, Chuck Bryant worked with cement, mixing it up to his elbows, a texture he likened to oatmeal at first. Two days later, he noticed the worst dermatitis he had ever experienced on his right arm. The contact dermatitis from this exposure necessitated a prescription for steroids. He and his colleague Scotty, who also worked with the cement, employed measures like Benadryl, topical sprays, cortisone, and hot showers from a handheld showerhead to find some relief.

Challenges of Chronic Itching for Public Figures and Performers

Chuck also empathizes with a woman he refers to as Em, who had incessant itching that led to drastic measures. He finds parallels between his own experience and those with more extreme cases of itching that disallow a normal, public life.

Severe Itching Affects Quality of Life: A Podcast Case Study

Chuck Bryant relates a haunting story about a patient known as "M," underscoring the need for better treatment methods for chronic itching.

Hiv-related Shingles Led To Intractable Itch, Causing Woman to Scratch Through Skull, Resulting In Institutionalization

"M," a woman from Massachusetts who had lived through a divorce and heroin use which led to HIV infection, developed shingles. After her shingles subsided, she endured such severe itching that she was unable to control her scratching, especially at night. This tragically led to self-injury severe enough that she scratched through her skull, necessitating her to be taken to an emergency room and likely leading to her institutionalization.

A skin graft given to her as treatment was later scratched away, illustrating the severity of her itch. Her condition was so dire that doctors believed the itch was due to the nerve endings damaged b ...