Boulder County & North Metro Neurosurgery
Peter Lennarson, MD, FAANS
Board-Certified Neurosurgeon
Associate Professor of Clinical Practice
Peter Lennarson, MD, FAANS, is a board-certified neurosurgeon and Associate Professor of Clinical Practice in the Department of Neurosurgery at the University of Colorado School of Medicine. With more than two decades of neurosurgical experience, his practice focuses on complex spinal disorders, minimally invasive and reconstructive spine surgery, and spinal cerebrospinal fluid (CSF) leaks. He holds leadership roles in the university's CSF Leak Program and neurosurgical spine fellowship and provides care to patients in Longmont and surrounding communities.
About the Provider
Peter Lennarson, MD, FAANS, is a board-certified neurosurgeon employed by CU Medicine and an Associate Professor of Clinical Practice in the Department of Neurosurgery at the University of Colorado School of Medicine. He has practiced neurosurgery since completing his residency at the University of Iowa in 2001, with experience spanning academic medical centers, community neurosurgical practice, and military medicine.
Dr. Lennarson specializes in the evaluation and treatment of complex spinal conditions, including degenerative spine disorders, spinal deformity, traumatic injuries, and disorders involving the junction between the skull and spine. His practice includes minimally invasive approaches and complex spinal reconstruction when appropriate. He emphasizes careful evaluation, clear explanations, and consideration of nonsurgical treatment options alongside surgical care.
A major focus of Dr. Lennarson's work is the diagnosis and treatment of spinal cerebrospinal fluid (CSF) leaks. He serves as Co-Director of the University of Colorado's multidisciplinary CSF Leak Program and Director of its CSF Dynamics/CSF Leak Surgical Program. Working closely with neuroradiology, neurology, and other specialists, he helps evaluate patients with complex spinal CSF leaks, spontaneous intracranial hypotension, and CSF-venous fistulas. This collaborative approach brings together specialized diagnostic imaging, treatment planning, and surgical expertise when needed.
Dr. Lennarson also serves as Director of the University of Colorado Neurosurgery Spine Fellowship, contributing to the training of future spine surgeons. He has authored and coauthored numerous peer-reviewed publications addressing spinal CSF leaks, spinal disorders, neurosurgical trauma, and advances in diagnostic and surgical care.
Before joining the University of Colorado faculty, Dr. Lennarson served in the United States Air Force Medical Corps, including deployment as a neurosurgeon during Operation Iraqi Freedom. He has also held neurosurgical leadership positions in academic and community hospitals and remains involved in medical education, research, and professional service.
Dr. Lennarson provides neurosurgical care in Longmont, expanding access to academic neurosurgical expertise for patients from Boulder County and surrounding communities. His approach emphasizes listening to patients, explaining complex conditions in understandable terms, and developing individualized treatment plans that reflect each patient's needs and goals.
Clinical Expertise & Interests
Complex Spine Surgery
Degenerative spinal disorders, disc herniation, stenosis, instability, spinal deformity, and reconstructive surgery.
Spinal CSF Leaks
Specialized evaluation of spinal CSF leaks, spontaneous intracranial hypotension, and CSF-venous fistulas.
Minimally Invasive Spine Surgery
Consideration of minimally invasive approaches and complex spinal reconstruction based on the condition and patient.
Craniovertebral & Spinal Trauma
Complex disorders at the junction between the skull and spine, Chiari malformation, and traumatic spinal conditions.
Advancing the Diagnosis and Treatment of Spinal CSF Leaks
Dr. Lennarson serves as Co-Director of the University of Colorado CSF Leak Program, which provides multidisciplinary evaluation and treatment for patients with complex spinal cerebrospinal fluid leaks.
Spinal CSF leaks can cause debilitating symptoms and may require specialized diagnostic imaging and coordinated evaluation by several medical specialties. Dr. Lennarson collaborates with neuroradiology and other clinical teams to identify the underlying causes of these conditions and determine appropriate treatment options.
In addition to patient care, he contributes to clinical research examining spinal CSF leaks, diagnostic techniques, and treatment approaches. His work helps connect specialized academic expertise with the broader neurosurgical care available to patients in Boulder County and northern Colorado.
Patients requiring the specialized CSF Leak Program are evaluated through the appropriate institutional pathways at the University of Colorado Anschutz Medical Campus.
Education & Training
Medical school
University of Wisconsin School of Medicine and Public Health
Residency
University of Iowa Hospitals and Clinics Program
Undergraduate
University of Wisconsin–Madison
Board Certification
Neurological Surgery - American Board of Neurological Surgeons
Academic Appointment
Associate Professor of Clinical Practice
University of Colorado School of Medicine
Professional Profiles & Links
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Practice Locations
Longs Peak Hospital
UCHealth Neurosciences · Hospital-based care
Spine Center – Anschutz Outpatient Pavilion
UCHealth Spine Center - Outpatient Clinic
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