Many patients experience high symptom burden for many years following moderate-to-severe traumatic brain injury (TBI). Here, we use the Rivermead Post-Concussion Symptoms Questionnaire (RPQ), a self-report questionnaire that tracks the severity of chronic symptoms that impact quality of life, to evaluate longitudinal changes following deep brain stimulation (DBS) in participants with chronic, moderate-to-severe TBI (msTBI), and to compare findings to the natural recovery observed in the TRACK-TBI Longitudinal cohort. The DBS cohort consisted of the five participants with msTBI in the CENTURY-S trial (CENtral Thalamic Deep Brain Stimulation for the Treatment of Traumatic Brain InjURY, NCT02881151) who received DBS. The total mean RPQ score decreased from 35.0 (SD 8.7) to 18.4 (SD 18.5). 3 participants reporting 10, 8, and 4 symptoms (of a possible 16) as moderate or severe at baseline reported 0 symptoms at this level at treatment end. A fourth participant showed a 50% decrease in the number of moderate to severe symptoms, from 10 to 5. A sample of 107 patients with msTBI from the TRACK-TBI Longitudinal study served as a comparison group. The TRACK-TBI Longitudinal RPQ total score remained stable from one-year post-injury (mean 13.84. SD 12.61) to the first follow-up at either 2, 3, 4, or > 5 years post-injury (mean 14.47, SD 12.98). More TRACK-TBI Longitudinal participants experienced worsening moderate to severe symptoms than improvement (Increased: N=44; Decreased: N=28; No change: N= 28). Participants in the CENTURY-S trial with chronic msTBI (3 to 18 years post injury) achieved marked improvements after DBS in total symptom burden and in the number of symptoms reported as moderate to severe in contrast to participants in the TRACK-Longitudinal sample whose RPQ scores remained stable. These observations suggest that DBS of the central lateral thalamus alleviates chronic TBI-related symptoms, surpassing the natural recovery documented in the TRACK-TBI Longitudinal cohort.