Humboldt Neurological Medical Group
Our Physicians
John P. Gambin, M.D.

Dr. Gambin is one of the founding partners of Humboldt Neurology,
arriving in Eureka in 1976. He is also co-director of the Sleep Disorders
Center at St. Joseph Hospital. As of June 30,2012, Dr. Gambin retired
from his practice in clinical neurology, however is still accepting new
patients in the field of sleep medicine.
Kurt M. Osborn, M.D.

Dr. Osborn, a founding partner of Humboldt Neurology, arrived in
Eureka in 1977. He is also co-director of the Sleep Disorders Center
at St. Joseph Hospital. As of June 30,2012, Dr.Osborn retired from
his practice in clinical neurology, however is still accepting new
patients in the field of sleep medicine.
Donald J. Iverson, M.D.

Dr. Iverson joined Humboldt Neurology in 1989. In addition to his clinical
practice, he serves on subcommittees of the American Academy of Neurology
that create treatment guidelines and quality measurements. He has recently
published articles on neuromuscular disease, vertigo, driving in dementia,
and Parkinson's disease. He has previous board certification in Clinical
Neurophysiology. Dr. Iverson speaks conversational / medical Spanish.
Melissa A. McKenzie, D.O.

Dr. McKenzie has been in practice with Humboldt Neurology since 2004. She treats
patients in all aspects of neurology. In addition, she is a preceptor/adjunct faculty
member of Touro University, College of Osteopathic Medicine.
  • University of California - Irvine- 1971
  • Board Certification: American Board of Psychiatry and Neurology - 1979
  • Board Certification: American Academy of Sleep Medicine - 1997
Phone  (707) 443-9385                     2828 O'Neil Lane, Eureka, CA 95503                              Fax (707) 443-0258
  • Michigan State University- College of Osteopathic Medicine -1999
  • Board Certification: American Board of Psychiatry and Neurology - 2006
  • University of Wisconsin School of Medicine - 1970
  • Board Certification: American Board of Psychiatry and Neurology - 1979
  • Board Certification: American Academy of Sleep Medicine - 1997
  • UCLA, Medical School - 1985
  • UCLA Neuropsychiatric Institute: Residency - 1989
  • Board Certification: American Board of Psychiatry and Neurology - 1993
  • Fellow of the American Academy of Neurology (AAN)
  • Fellow of the Royal Society of Medicine
Tiffany B. Ward, M.D.

Dr. Ward joined our practice in August of 2011. She has relocated to our area from
southern California seeking a more rural environment to practice medicine and a raise
a family.  She treats patients in all aspects of neurology.
Updated 10-22-2013
  • Meharry Medical College, Nashville, TN - 2005
  • Loma Linda University: Residency 2006-2009
  • Neurophysiology Fellowship, UCSD - 2010