Alex Linn, M.D.
Alex Linn, M.D. is a Vascular Neurology Physician in Sioux Falls, SD, registered under NPI 1003177338. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 1301 S CLIFF AVE STE 610, Sioux Falls, SD 57105. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 11423 | SD | Vascular Neurology Physician primary |
| 11423 | SD | Neurology Physician |
This provider holds licence 11423 issued in SD. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - Neurology
- PAC ID
- 0244453140
Medicare enrolment is recorded as approved under the provider type Practitioner - Neurology. This means the provider is enrolled to bill Medicare, though it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Vascular Neurology covers
Vascular Neurology is a subspecialty in the evaluation, prevention, treatment and recovery from vascular diseases of the nervous system. This subspecialty includes the diagnosis and treatment of vascular events of arterial or venous origin from a large number of causes that affect the brain or spinal cord such as ischemic stroke, intracranial hemorrhage, spinal cord ischemia and spinal cord hemorrhage. NUCC Health Care Provider Taxonomy, code 2084V0102X
All registered taxonomy codes
This provider registers 2 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 2084V0102X | Vascular Neurology Physician Vascular Neurology | 11423 | SD | primary |
| 2084N0400X | Neurology Physician Neurology | 11423 | SD |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1003177338 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jun 4, 2012 |
| Last updated | May 6, 2026 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | M.D. |
| Practice address |
1301 S CLIFF AVE STE 610 Sioux Falls, SD 57105 (605) 322-8860 Fax (605) 322-8868 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 0 | 0 | 3 | 1 | 7 | 7 | 3 | 3 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 0 | 3 | 2 | 7 | 5 | 3 | 6 |
Sum = 52 · next multiple of 10 = 60 · check digit = 8 · actual last digit = 8
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.