The Amazing Brainstem and the Head Neural Integrator: A Physical Therapist's Perspective
I would like to extend my sincere gratitude to Dr. Jeremy Schmoe, DC, DACNB, FACFN, FABBIR. He is the Founder and Clinical Director of The Functional Neurology Center, and he has done an outstanding job of laying out a clear, comprehensive description of this very complex system.
His work on this topic is genuinely brilliant.
This article is my re-interpretation of his excellent article, 'The Head Neural Integrator,' which you can find here: https://substack.com/home/post/p-173220715.
As a physical therapist who specializes in dizziness and balance disorders, I spend my days trying to figure out the root cause of my patients' instability. What I have found, and what Dr. Schmoe so brilliantly explains, is that the issue often stems from a malfunctioning head neural integrator. When this crucial system fails, it's not always a direct injury; more often, it is a consequence of the brain trying to compensate for a faulty vestibular system. The brain develops what we call a maladaptive sensory strategy, which ultimately causes the very instability it's trying to prevent.
You may have heard of the ocular neural integrator, a circuit that keeps your eyes stable when you look to the side. The head has its own version, a dynamic system that performs the same function for your head and neck. When it works well, you do not even notice it. You seamlessly tilt your head, track a moving target, and combine head movements with posture without thinking.
However, when a vestibular dysfunction disrupts your balance, your brain starts over-relying on other senses—like vision or input from your neck—to keep you stable. This leads to a maladaptive sensory mismatch, and over time, the head neural integrator falters. The symptoms can be profound: drifting head postures, difficulty with head-eye coordination, dizziness with positional changes, and unstable visual perception.
What is the Head Neural Integrator?
Think of a neural integrator as a circuit that takes quick, brief commands and turns them into a sustained, stable position. For your head, this integrator receives input from your vestibular system (your inner ear), proprioceptive information from your neck, and other sensory data, and uses it to maintain the stability of your head against gravity.
Dr. Schmoe points out, citing a 2024 article in Movement Disorders by Shaikh, Straube, and Brandt, that this system is distributed throughout the brain, involving the vestibular nuclei, the interstitial nucleus of Cajal, the cerebellar nodulus, the uvula, and the flocculus. The integration of all this information allows you to:
Hold an eccentric head position without drift.
Keep your head stable during combined eye and head movements.
Coordinate your posture during gaze shifts and body turns to maintain a stable position.
Adjust your orientation to gravity during tilts and rotations.
This is not a static, mechanical system. The head neural integrator is a dynamic, adaptive circuit that requires continuous learning and precise timing across multiple sensory channels. When the brain adopts a maladaptive strategy, it loses this accurate timing, leading to instability.
Clinical Clues: When a Maladaptive Strategy Causes the System to Break
As a physical therapist, I see these problems every day. Patients with head neural integrator dysfunction show subtle—but essential—signs that reveal their maladaptive strategies:
Their head drifts when they try to hold a tilt or rotation, as their brain over-relies on inaccurate muscle tension.
Their eyes overshoot or lag behind their head when they combine the two movements, a sign of a visual-vestibular mismatch (VVM).
They get positional dizziness with particular tilts or postures.
They struggle with visual stabilization when they move their head out of the midline.
They get neck strain and fatigue from over-recruiting muscles to compensate for faulty neural integration. This is a classic example of a somatosensory-vestibular mismatch (SVM).
I often see these signs in people who have suffered concussions, whiplash, or vestibular disorders. The common thread is that the patient's head is no longer being stabilized by its critical neural circuit. Instead, they rely on muscle tension, vision, or other bad strategies.
Our Approach to Treatment at FYZICAL
At FYZICAL, we employ a specialized, multimodal approach to assessing and retraining the head's neural integrator. We often utilize our proprietary Safety Overhead Support System (SOS) to help prevent patients from falling.
Motion Guidance: We utilize laser feedback tools to evaluate a patient's ability to maintain head positions against a target. This makes drift patterns obvious, allowing us to track their progress during training.
The FYZICAL Balance Paradigm: We challenge patients with a series of head-eye movements. This includes gaze stabilization drills combined with head tilts, rotations, and postural shifts. We use this to stress the head neural integrator while integrating the ocular and vestibular pathways and retraining the brain to abandon maladaptive strategies.
Infrared Video Oculography (IVOG): We often use IVOG to assess head postural challenges and observe how the eyes respond to eccentric head positions. This is one of the best ways to observe integrator dysfunction in real-time.
Postural & Cervical Retraining: We incorporate cervical proprioceptive drills, laser-guided tracking, and balance exercises with visual-vestibular integration.
Our goal is not just to strengthen a patient's neck muscles. We aim to restore the neural maps that stabilize the head against gravity, allowing for seamless coordination with the eyes. This work is crucial in restoring our patients' health and quality of life.
The Cerebellum's Role
The cerebellum is a key player in the central nervous system's neural integrator. It processes velocity storage and fine-tunes your orientation to gravity. This is why patients with cerebellar dysfunction cannot hold their head or eyes steady in eccentric positions—their integrators 'leak,' which leads to drift, oscillations, or head instability.
Rehabilitation: Turning a Maladaptive Strategy into Stability
Rehab for the head neural integrator, as Dr. Schmoe specifically describes, gives the system accurate sensory input and structured challenges:
Start with Midline Stability: We first ensure that patients can hold a neutral head posture without drift or fatigue.
Add Eccentric Holds: We use lasers or motion guidance to train patients to maintain accuracy in tilted or rotated postures.
Layer Eye Movements: Once head holding improves, we add saccades, pursuits, and VOR drills combined with head positioning.
Challenge Gravity: We incorporate tilts, inclines, and balance surfaces to integrate gravitational signals.
Integrate into Function: We utilize sports drills, daily movement tasks, and dual-tasking exercises to ensure the patient can apply these skills in real-world settings.
Why This Matters
The head neural integrator may not be a household term, but it is a cornerstone of my profession. Without a functioning integrator, patients cannot stabilize their world, coordinate their gaze, or move confidently through space. With it, even subtle improvements can unlock balance, reduce dizziness, and improve a patient's visual comfort.
We are not just training the neck or the eyes. We are retraining the brain's ability to integrate them into a seamless map of stability. When that map is restored, patients do not just feel better—they feel like they can trust their body again.
References of Dr. Schmoe
Shaikh AG, Straube A, Brandt T. (2024). The neural integrator of the head: A neural circuit for head posture control. Movement Disorders, 39(1), 12–24. https://doi.org/10.1002/mds.70014
Leigh RJ, Zee DS. (2015). The Neurology of Eye Movements (5th ed.). Oxford University Press.
Peterson BW, Goldberg J, Cullen KE. (2004). Central vestibular system. In Paxinos G (Ed.), The Rat Nervous System. Elsevier.
Cullen KE. (2012). The vestibular system: Multimodal integration and encoding of self-motion for motor control. Trends in Neurosciences, 35(3), 185–196.
Cohen B, Komatsuzaki A. (1972). Eye-head coordination in labyrinthine-deficient monkeys. Brain Research, 36(2), 336–340.
Brian K. Werner, PT, MPT, is a physical therapist who specializes in vestibular and balance disorders. He is the co-founder of the Physical Balance Paradigm and the National Director of Vestibular Education & Training at FYZICAL. He has spent over a quarter of a century helping people find their balance.
5 years ago when I tipped my toe in the waters of vestibular rehabilitation from a diverse background of ortho/sports medicine and then to neurology, I noted a similar phenomenon between vestibular patients and patients with a neurological (CNS) insult - a head tilt.
This article explains many things across our profession - thank you for continuing to bring us together with didactic information that promote sound clinical practice.