Management of patients with cervical myelopathy and normal pressure hydrocephalus: Epidemiology, medical and surgical complications.

Objective: Normal pressure hydrocephalus (NPH) and degenerative cervical myelopathy (DCM) can each lead to gait dysfunction and urinary incontinence and may occur concurrently in some patients. In patients presenting with NPH and DCM, there is a paucity of literature describing the medical and surgical complications of treatment and the potential consequences of the sequence of surgical procedures. The aim of this study is to evaluate patients with DCM, NPH, and dual pathology to determine epidemiology and how the order of surgical intervention for both conditions may impact complications and patient outcomes.

Methods: The PearlDiver Mariner database was queried between 2010 and 2020 to identify patients by their diagnosis of NPH, DCM, or both. Additional groups were created to identify cohorts of patients who underwent ventriculoperitoneal (VP) shunting, DCM surgery, or both surgeries, as determined by the CPT, ICD9, and ICD10 codes included in the dataset. Overall demographics were reported for these cohorts of patients including age, gender, and region. Multivariable logistic regression, controlling for age, sex, and Charlson Comorbidity Index, was used to calculate odds ratios for the rates of perioperative complications within 1 year of initial ventriculoperitoneal (VP) shunt and/or DCM surgery.

Results: A total of 825,989 patients were identified with DCM and/or NPH: 725,433 (87.8%) had myelopathy alone, 96, 411 (11.7%), had NPH alone, and 4145 patients (0.5%) had both NPH and DCM. Of all patients with NPH, 4.8% underwent DCM surgery. Of all patients with DCM, 0.08% underwent VP shunting. Compared to NPH only patients who underwent VP shunting, patients with both pathologies undergoing VP shunting had higher odds of revision at 1-year (OR: 1.33, p-value: 0.04) and 5-years (OR: 1.36, p-value: 0.011), as well as spinal cord injury (OR: 7.77, p-value 0.016), dysphonia (OR: 2.88, p-value: 0.004), cervicalgia (OR: 2.95, p-value: 0.004), cervical kyphosis (OR: 17.49, p-value: 0.004), and limb paralysis (OR: 2.02, p-value: 0.002). Compared to DCM only patients who underwent DCM surgery, patients with both pathologies undergoing DCM surgery had higher odds of cardiac complications (OR: 1.12, p-value: 0.002), dural tear (OR: 1.66, p-value: 0.029), and dysphagia (OR: 1.28, p-value: <0.001). Patients who underwent VP shunting prior to DCM surgery had higher odds of revision shunting surgery at 1-year (OR:1.61, p-value:0.03) and 5- years (OR:2.16, p-value: <0.001).

Conclusion: This is the largest study to date examining patients with dual cervical myelopathy and normal pressure hydrocephalus. Surgeons should carefully consider the order of VP shunting and DCM surgery, as complication rates differ depending on the order in which these surgeries are performed. Shunt revision is more common when VP shunting is performed prior to spinal decompression.