Medical School
- MD, University of Wisconsin School of Medicine and Public Health (1995)
Undergraduate School
- BS, University of Wisconsin–Madison (WI) (1991)
Internship
- University of Iowa Hospitals and Clinics Program (1996)
Residency
- University of Iowa Hospitals and Clinics Program, Chief Resident, Neurosurgery (2001)
Languages
English, SpanishDepartment
NeurosurgeryProfessional Titles
- Associate Professor
Research Interests
My research interests include traumatic brain and spine injuries and their treatment and diagnosis, evaluation and management of spontaneous and secondary spinal fluid leaks.Publications
- Callen AL, Khanwalkar AR, Cunningham ML, Pisani Petrucci SL, Bhaumik D, Wilhour D, Trivedi P, Lennarson P, Zander DA. Revisiting a Rare Anomaly Described 25 Years Ago in the AJNR: A Journey from Pediatric Hemifacial Microsomia and Middle Cranial Fossa Aplasia to CSF-Lymphatic Fistula and Spontaneous Intracranial Hypotension as an Adult. AJNR Am J Neuroradiol. 2025 Mar 27:ajnr.A8760. doi: 10.3174/ajnr.A8760. Epub ahead of print. PMID: 40147836.
- Callen AL, Pisani Petrucci SL, Bhaumik D, Lennarson P, Birlea M, MacKenzie J, Ettenberg J, Jones LC. Enhancing Clarity in Dynamic Myelography Reporting: Results of a Survey of Patients and Referring Providers Evaluating a Standardized Reporting System in the Myelographic Workup of Patients with Suspected Spontaneous Intracranial Hypotension. AJNR Am J Neuroradiol. 2025 Mar 26:ajnr.A8751. doi: 10.3174/ajnr.A8751. Epub ahead of print. PMID: 40139902.
- Callen AL, Pisani Petrucci SL, Bhaumik D, Lennarson P, Birlea M, MacKenzie J, Ettenberg J, Jones LC. Enhancing Clarity in Dynamic Myelography Reporting: Results of a Survey of Patients and Referring Providers Evaluating a Standardized Reporting System in the Myelographic Workup of Patients with Suspected Spontaneous Intracranial Hypotension. AJNR Am J Neuroradiol. 2025 Mar 26:ajnr.A8751. doi: 10.3174/ajnr.A8751. Epub ahead of print. PMID: 40139902.
- Campbell C, Montes D, Bhaumik D, Lennarson P, Callen AL. The Association of Spinal Meningeal Diverticula Number and Size with the Detection of CSF-Venous Fistulas: Evidence from a Contemporary Myelography Cohort. AJNR Am J Neuroradiol. 2025 Dec 12. [Epub ahead of print] PubMed PMID: 41386989
- Puello MP, Trivedi P, Kerrigan K, Walters A, Bhaumik D, Lennarson P, Callen AL. Disparities in Access to Specialized Care for Spontaneous Intracranial Hypotension. AJNR Am J Neuroradiol. 2025 Oct 8. [Epub ahead of print] PubMed PMID: 41062183
- Freeman LM, Mecum A, Cripps MW, Lennarson PJ. The modified Brain Injury Guidelines: safe, sensitive, but not yet specific. J Neurosurg. 2025 Oct 1;143(4):999-1008. PubMed PMID: 40614279
- Callen AL, Montes D, Bhaumik D, Lennarson P, Mamlouk MD, Lützen N, Beck J, Urbach H, Scoffings D, Butteriss D, Carlton Jones L. Outcomes of CT-Guided Targeted Epidural Patching for Lateral Dural Tears in Spontaneous Intracranial Hypotension: A Multicenter Retrospective Cohort Study. AJNR Am J Neuroradiol. 2025 Dec 4;46(12):2685-2692. PubMed PMID: 40541530
- Mecum AV, Kleinschmidt-DeMasters BK, Bhaumik D, Pisani Petrucci SL, Lennarson PJ, Callen AL. Histopathologic Analysis of 5 Patients with CSF-Venous Fistulas after Surgical Nerve Root Ligation and Resection. AJNR Am J Neuroradiol. 2025 Oct 1;46(10):1967-1971. PubMed PMID: 40210461
- Callen AL, Khanwalkar AR, Cunningham ML, Pisani Petrucci SL, Bhaumik D, Wilhour D, Trivedi P, Lennarson P, Zander DA. Revisiting a Rare Anomaly Described 25 Years Ago in the AJNR: A Journey from Pediatric Hemifacial Microsomia and Middle Cranial Fossa Aplasia to CSF-Lymphatic Fistula and Spontaneous Intracranial Hypotension as an Adult. AJNR Am J Neuroradiol. 2025 Oct 1;46(10):2208-2213. PubMed PMID: 40147836
- Callen AL, Pisani Petrucci SL, Bhaumik D, Lennarson P, Birlea M, MacKenzie J, Ettenberg J, Carlton Jones L. Enhancing Clarity in Dynamic Myelography Reporting: Results of a Survey of Patients and Referring Providers Evaluating a Standardized Reporting System in the Myelographic Work-Up of Patients with Suspected Spontaneous Intracranial Hypotension. AJNR Am J Neuroradiol. 2025 Oct 1;46(10):2200-2207. PubMed PMID: 40139902
- Callen AL, Pisani Petrucci SL, Lennarson P, Sedrak MF, Gutierrez A, Mamlouk MD. Efficacy of Traditional Epidural Patching versus Patching within Spinal Longitudinal Extradural Collections for Ventral Dural Cerebrospinal Fluid Leaks. Radiology. 2025 Mar;314(3):e242194. PubMed PMID: 40131109
- Montes D, Pisani Petrucci SL, Bhaumik D, Andonov N, Lennarson P, Callen AL. Patterns of Epidural Patch Distribution: The Influence of Spinal Level, Injection Technique, and Patch Volume/Composition on Craniocaudal and Ventral Epidural Dispersion. AJNR Am J Neuroradiol. 2025 Sep 2;46(9):1931-1938. PubMed PMID: 40000121
- Lennarson PJ, Callen AL. Cerebrospinal Fluid Leaks: Diagnosis, Management, and Outcomes. Neurosurg Clin N Am. 2025 Jan;36(1):53-64. PubMed PMID: 39542549
- Pisani Petrucci SL, Andonov N, Lennarson P, Birlea M, O'Brien C, Wilhour D, Anderson A, Bennett JL, Callen AL. Assessing the Diagnostic Value of Brain White Matter Hyperintensities and Clinical Symptoms in Predicting the Detection of CSF-Venous Fistula in Patients with Suspected Spontaneous Intracranial Hypotension. AJNR Am J Neuroradiol. 2025 May 2;46(5):1036-1043. PubMed PMID: 39443147
- Montes D, Pisani Petrucci SL, Bhaumik D, Andonov N, Lennarson P, Callen AL. Patterns of Epidural Patch Distribution: The Influence of Spinal Level, Injection Technique, and Patch Volume/Composition on Craniocaudal and Ventral Epidural Dispersion. AJNR Am J Neuroradiol. 2025 Feb 25:ajnr.A8720. doi: 10.3174/ajnr.A8720. Epub ahead of print. PMID: 40000121.
- Callen AL, Pisani Petrucci SL, Lennarson P, Birlea M, MacKenzie J, Buchanan AJ; “Spinal CSF Leak: Bridging the Gap” Study Group. Perspectives from the Inaugural "Spinal CSF Leak: Bridging the Gap" Conference: A Convergence of Clinical and Patient Expertise. AJNR Am J Neuroradiol. 2024 Jul 8;45(7):841-849. doi: 10.3174/ajnr.A8181. PMID: 38697790; PMCID: PMC11286036.
- Pisani Petrucci SL, Andonov N, Lennarson P, Birlea M, O'Brien C, Wilhour D, Anderson A, Bennett JL, Callen AL. Assessing the Diagnostic Value of Brain White Matter Hyperintensities and Clinical Symptoms in Predicting the Detection of CSF Venous Fistula in Patients with Suspected Spontaneous Intracranial Hypotension. AJNR Am J Neuroradiol. 2024 Oct 23:ajnr.A8548. doi: 10.3174/ajnr.A8548. Epub ahead of print. PMID: 39443147.
- Pisani Petrucci SL, Andonov N, Lennarson P, Birlea M, O'Brien C, Wilhour D, Anderson A, Bennett JL, Callen AL. Assessing the Diagnostic Value of Brain White Matter Hyperintensities and Clinical Symptoms in Predicting the Detection of CSF Venous Fistula in Patients with Suspected Spontaneous Intracranial Hypotension. AJNR Am J Neuroradiol. 2024 Oct 23:ajnr.A8548. doi: 10.3174/ajnr.A8548. Epub ahead of print. PMID: 39443147.
- Lennarson PJ, Callen AL. Cerebrospinal Fluid Leaks: Diagnosis, Management, and Outcomes. Neurosurg Clin N Am. 2025 Jan;36(1):53-64. doi: 10.1016/j.nec.2024.08.003. Epub 2024 Sep 10. PMID: 39542549.
- Callen AL, Han L, Pisani Petrucci SL, Andonov N, Lennarson P, Birlea M, O'Brien C, Wilhour D, Anderson A, Bennett JL, Carroll IR. Patterns of clinical and imaging presentations in patients with spontaneous intracranial hypotension due to spinal cerebrospinal fluid venous fistula: A single-center retrospective cross-sectional study. Headache. 2024 Sep;64(8):939-949. doi: 10.1111/head.14805. Epub 2024 Aug 11. Erratum in: Headache. 2025 Jan;65(1):202. doi: 10.1111/head.14891. PMID: 39129307.
- Callen AL, Timpone VM, Schwertner, A, Zander D, Grassia, F, Lennarson P, Seinfeld J, Lillehei K, Birlea M, Thaker AA: Algorithmic, Multimodality Approach to Diagnosis and Treatment of Spinal CSF Leak and Venous Fistula in Spontaneous Intracranial Hypotension, American Journal of Roentgenology, In press https://doi.org/10.2214/AJR.22.27485
Professional Memberships
- American Association of Neurological Surgeons, Fellow
- Congress of Neurological Surgeons, Member
- Colorado Medical Society, Member
- Colorado Neurosurgical Society, Member
- Denver Medical Society, Member
Practice Locations
UCHealth Spine Center - Anschutz Medical CampusAnschutz Inpatient Pavilion - 1st Floor
12605 E. 16th Avenue
Aurora, CO 80045
720-848-1980
UCHealth University of Colorado Hospital Trauma Center
12505 E. 16th Avenue
Anschutz Inpatient Pavilion 2, First floor
Aurora, CO 80045
720-848-2711
Hospital Affiliation
- University of Colorado Hospital
Specialty Information
Specialties- Neurological Surgery, Board Certification (2006)
- Bones, Joints and Muscles - Spine Injuries
- Bones, Joints and Muscles
- Bones, Joints and Muscles - Neck Disorders and Injuries
- Bones, Joints and Muscles - Back Pain
- Brain and Nervous System - Traumatic and Acquired Brain Injuries
- Brain and Nervous System
- Brain and Nervous System - Trauma / Nerve Injuries
- Brain and Nervous System - Spine Diseases and Conditions
- Spine
- Spine - Cervical disc herniation
- Spine - Cervical spinal stenosis
- Spine - Degenerative Disc Disease
- Spine - Degenerative Scoliosis
- Spine - Lumbar disc herniation
- Spine - Lumbar spinal stenosis
- Spine - Myelopathy
- Spine - Radiculopathy
- Spine - Sciatica
- Spine - Slipped Disc
- Spine - Spondylolisthesis
- Spine - Spondylolysis
- Spinal Deformity
- Surgery - Neurosurgery
- Surgery
- Failed Prior Surgery
- Symptoms and Manifestations - Pain
- Symptoms and Manifestations
Clinical Interests
Cerebrospinal fluid leaks both spontaneous and secondary. Degenerative and traumatic spinal disorders--from the base of the skull down to the neck and back as well as the tail bone and sacro-iliac joints. Cranio-vertebral junction disorders. (Arnold) Chiari Malformation. Minimal Access / minimally invasive surgical techniques.
Care Philosophy
While having practiced the full breadth of neurosurgery my work has increasingly focused on the many complicated spine problems that so many suffer from. These problems include common issues of the degenerative spine such as herniated discs to tumors and spinal fluid leaks. From outpatient, minimally invasive surgeries to large complex deformity operations there is no problem too little nor too great that does not interest me. Even as a surgeon, it is still my hope to help you in non-surgical ways when possible, but I will be committed to developing whatever plan is required to solve your problems. I place great emphasis on helping you understand your problem in straight forward terms. I will respect you as a partner in maintaining your health and will listen and seek to understand your questions and concerns so that we can work together to make treatment plans that meet your needs.
Cerebrospinal fluid leaks both spontaneous and secondary. Degenerative and traumatic spinal disorders--from the base of the skull down to the neck and back as well as the tail bone and sacro-iliac joints. Cranio-vertebral junction disorders. (Arnold) Chiari Malformation. Minimal Access / minimally invasive surgical techniques.
Care Philosophy
While having practiced the full breadth of neurosurgery my work has increasingly focused on the many complicated spine problems that so many suffer from. These problems include common issues of the degenerative spine such as herniated discs to tumors and spinal fluid leaks. From outpatient, minimally invasive surgeries to large complex deformity operations there is no problem too little nor too great that does not interest me. Even as a surgeon, it is still my hope to help you in non-surgical ways when possible, but I will be committed to developing whatever plan is required to solve your problems. I place great emphasis on helping you understand your problem in straight forward terms. I will respect you as a partner in maintaining your health and will listen and seek to understand your questions and concerns so that we can work together to make treatment plans that meet your needs.
Personal Interests
I have a passion for my work and continue to study and learn the science and art of neurosurgery and spine surgery even outside the traditional work environment. I am often engrossed in contemplating a new treatment or surgical procedure and figuring out how I can adopt it to better the lives of my patients. Outside of my profession I enjoy the Colorado outdoors including hiking, trail running, biking, skiing, fishing and camping. Best of all is when I can combine these activities with my wife and 5 boys.
Volunteer Activities
Return to Duty (501c3 non-profit): Helping Special Operations Forces with spine injuries receive the healthcare options, education and care they need. Medical Advisory Team Member, Spinal CSF Leak Canada. Medical Advisory Board Member, CSF Leak Foundation (United States).
I have a passion for my work and continue to study and learn the science and art of neurosurgery and spine surgery even outside the traditional work environment. I am often engrossed in contemplating a new treatment or surgical procedure and figuring out how I can adopt it to better the lives of my patients. Outside of my profession I enjoy the Colorado outdoors including hiking, trail running, biking, skiing, fishing and camping. Best of all is when I can combine these activities with my wife and 5 boys.
Volunteer Activities
Return to Duty (501c3 non-profit): Helping Special Operations Forces with spine injuries receive the healthcare options, education and care they need. Medical Advisory Team Member, Spinal CSF Leak Canada. Medical Advisory Board Member, CSF Leak Foundation (United States).